The Title Goes Here With Each Initial Letter Capitalized by tommyadams

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									     Engineering with the Environment, working with the environment to
                               improve access

                   Mike James, Independent Consultant, United Kingdom

         Peter O’Neill, Department for International Development, United Kingdom

     David Salter, South East Asia Community Access Programme (SEACAP), Cambodia


1.     Introduction                              1. Maximize the use of local resource
                                                    based technologies.
SEACAP
                                                 2. Maximize       the   use of spot
The South East Asia Community Access
                                                    improvements to remove priority
Programme – SEACAP, is a DFID
                                                    obstacles to access.
(Department of International Development
– UK based), funded programme the goals          3. Select the appropriate solution to
of which are                                        access   problems        based    upon
                                                    minimizing full life cycle costs.
a. To help and support developing
   countries make the optimal decisions          The SEACAP research work carried out
   on providing rural access to remote           provides sound evidence for stakeholders
   poor communities                              on the technical, financial and economic
                                                 viability of the premises.
b. To    improve     sustainability  and
   affordability of rural access to poor         Rural Access
   countries
                                                 Studies carried out in SE Asia find a
c. Create opportunities for pro-poor             strong correlation between access to basic
   growth and poverty alleviation.               infrastructure services and the incidence of
                                                 poverty. For example, in Lao PDR the
The objectives of the Programme are to
                                                 very poor (estimated to some 17 per cent
improve livelihoods of poor and
                                                 of the population) live in remote areas
vulnerable people in SE Asia and include
                                                 where infrastructure is especially scarce.
empowering local ownership of their
                                                 Villages in the Northern region are
access. This includes initiatives that
                                                 particularly isolated; some have no access
improve community access by ensuring
                                                 to social services even during dry season.
that roads and spot improvements are
constructed and maintained in a                  A Poverty Impact Study of rural roads
sustainable way by maximizing the                constructed under the Lao Swedish Road
appropriate use of local resources               Sector Project indicated that all villages,
including: materials, labour, enterprise and     having been provided with road access, to
ingenuity. More affordable in capital and        a greater or lesser extent were now
recurrent costs, these local road solutions      producing more in general, than before.
have become the spine of local                   Expenditures had increased more than
government policy and this programme is          threefold; there was evidence of positive
designed to expand the successes of the          impact on education, health, commerce,
initial research work.                           agriculture, land use and reduced gender
                                                 inequalities and decreased transport costs.
SEACAP     advocates   three  simple
                                                 These finding reflect the general benefits
approaches for achieving sustainable
                                                 of providing access to rural communities.
community access:



                                           -1-
Poor people often rely on non-motorised           communities while at the same time
transport, motorcycles and simple trucks          reducing the dependence on increasingly
for their transport needs. On many soils, an      scarce natural resources.
engineered earth road is sufficient to
                                                  Environmental Issues
provide basic access for these vehicle
types, provided that specific, limited            Providing access to these communities can
location constraints, such as watercourse         have adverse environmental consequences.
crossings and steep gradients are                 Rural access roads require large quantities
adequately      engineered     with    spot       of gravel, which is often produced in large
improvements. The camber and drainage             quarries and transported over long
must of course be maintained using                distances on roads not designed for heavy
appropriate, low cost techniques.                 traffic and through villages, with
                                                  corresponding environmental and road
Low cost construction and maintenance             safety impacts. Large scale quarry
techniques using local labour and simple          operations themselves have associated
equipment have an important role to play.         environmental impacts, more so when
These techniques are particularly suitable        poorly managed which is often the case in
for implementation by small enterprises or        remote areas where strict controls are
communities. They use the locally                 difficult to enforce.
available labour and have negligible
capital requirements. Engineered Natural          The roads can also have serious effects on
Surfaces can be provided for less than            the environment such as erosion on steep
US$2,000 per km in many situations,               grades, which often cause similar damage
including the necessary low cost drainage         to the adjacent land, and landslides caused
measures.                                         by cutting or widening the road bench in
                                                  mountainous regions. These issues are not
However in some circumstances the in-situ         always addressed when providing basic
soils are just too weak to support any            access to rural communities due to the cost
traffic in the wet, and must be covered. For      implications and ways must be sought to
these situations, there is a range of             mitigate these adverse effects with low
alternative surfacing and paving options          cost local resource based solutions.
already proven in various countries that
could provide appropriate, economical and         Communities themselves could use some
sustainable alternatives to natural gravel in     of the techniques discussed in this paper to
developing countries. Suitability will            improve their own access. The alternative
depend on local circumstances. These              surfaces have lower (and more manageable)
alternatives, involving the appropriate use       maintenance requirements than gravel, not
of locally available materials, may be            only in terms of cost but also by reducing
cheaper in whole-life-cost terms. Many            the need for heavy equipment to transport
can be carried out by small and medium            and compact. Their environmental impact
enterprises using low-capital, labour based       is     potentially    substantially     less.
and light equipment methods.                      Furthermore, the use of bioengineering
                                                  techniques for slope stabilization is also
Even so, with limited funding available to        within the capability of communities while
rural communities and roads authorities,          providing      environmentally      friendly
there is often insufficient funding to            solutions to these problems.
rehabilitate all the rural roads. Approaches
must therefore be sought which can                SEACAP Approach
maximise the use of these funds. The use          Through the SEACAP and other initiatives,
of spot repairs to make roads accessible          DfID is exploring solutions to these issues.
and the exploitation of local gravel sources      The research carried out in Vietnam on the
can increase the available access to rural


                                            -2-
loss of gravel from road surfaces has              horizontal layers (1-1.5m), hence the
provided important data relating to the            development of borrow areas inevitably
sustainability of unpaved surfaces. The            carries “green environment” penalties. For
results of this research have reinforced the       example, each kilometer of a 3.5m wide
need for more sustainable pavement                 gravel surfaced rural road will require the
materials and approaches to pavement               opening up and excavation of a minimum
construction and road design strategies,           of 30mx30m borrow area (assuming a 1m
which have been explored under SEACAP              thick deposit layer) as well as attendant
projects in Cambodia, Vietnam, Lao PDR,            overburden dumps and access haulage
and Sri Lanka. Further research is ongoing         roads. In addition, as deposits are used up,
into the use of bioengineering techniques          subsequent periodic re-gravelling will
for slope stabilisation in Lao PDR.                involve longer hauls from ever more
                                                   distant sources and consequently higher
Key aspects of the research, completed,
                                                   maintenance costs.
ongoing and planned, include:
                                                   Under an ILO rural road project in
•    Investigation of naturally occurring
                                                   Cambodia, there were concerns regarding
     unimproved gravel as a suitable
                                                   the sustainability of gravel/laterite roads in
     pavement material;
                                                   many locations. The ILO Upstream Project
•    Low cost alternative surfaces and             reported the experiences of gravel loss and
     pavements;                                    maintenance in Battambang Province,
•    Spot repairs and improvements;                Cambodia. The report highlighted the
                                                   serious    environmental        and     social
•    Exploitation of local gravel sources          consequences of the use of gravel as a
     using mobile crushers;                        surfacing material, the very high overall
•    Combining     bioengineering   and            cost and the lack of sustainability of the
     geotechnical engineering for slope            approach.
     stability                                     Recent research under SEACAP indicates
The following chapters summarise the               that gravel may not be appropriate for use
gravel loss research, alternative sustainable      where any of the following conditions
pavements and other approaches to                  apply:-
providing sustainable access to rural              •   Gravel quality is poor – Gravel should
communities.                                           comply with internationally recognized
2.      Gravel loss                                    grading and plasticity requirements,
                                                       and resistance to break down under
The Limitations of Gravel                              traffic, otherwise it will be lost from
The word gravel is used within this                    the surface at a high rate.
document to denote any naturally                   •   Compaction & thickness cannot be
occurring granular material, including                 assured – uncompacted surface gravel
laterite gravel, used as a road surfacing              will be less durable.
material. Gravel is a „wasting‟ surface.
Material is lost from the surface of the           •   Haul distances are long – if haul
road due to the action of traffic and rainfall         distances are longer than 10km, then
Gravel should only be used for rural road              other surface types may be cheaper in
surface applications in situations where               whole life cost terms. Hauling gravel
certain conditions are fulfilled.                      for    construction    and     periodic
                                                       maintenance often causes damage or
Gravel is a natural and finite resource that           further maintenance liabilities to the
is found in limited quantities. It tends to            haulage routes.
occur in relatively thin, generally


                                             -3-
•   Rainfall is very high – Gravel loss is          the road surface at rates of more than 3cm
    directly related to rainfall and may be         per year, leading to the need to re-gravel at
    excessive with intense storms or where          very frequent intervals.
    annual precipitation is greater than            Fortunately there is a range of proven
    2,000mm.                                        alternatives to natural gravel. Some of
   There are dry season dust problems –            these have similar initial construction costs
    long dry seasons can allow the binding          to gravel in certain circumstances. Most
    fines to be removed from the surface            have higher initial costs but have better
    by traffic or wind. The removal of              whole life cost, attributes and lower
    fines from the road surface accelerates         maintenance liabilities.
    the wearing process and the suspended           Rural  Road   Gravel            Assessment
    dust causes environmental and health            Programme (RRGAP)
    problems for exposed humans and
    livestock.     This     is particularly         The Ministry of Transport (MoT) Second
    problematic where communities live              Rural Transport Project (RT2) in Vietnam
    beside the road or their crops and              provided basic access roads for
    property are regularly coated in dust.          communities in 40 provinces of Vietnam
    For example the inhalation of road dust         (2001–2005). Gravel was traditionally the
    is very unhealthy and there are also            surface provided for all of the project
    visibility-safety issues.                       roads. However, because of increasing
                                                    recognition that gravel surfacing is not
•   Traffic levels are high – gravel loss           always the best solution for rural roads in
    increases with traffic. It is unlikely that     all circumstances in Vietnam, studies of
    a gravel surface will be cost-effective         alternative    surfacing/paving       were
    at traffic flows of more than 200               conducted under the RRGAP.
    passenger car units per day.
                                                    The RRGAP scoping study revealed that
•   There are Longitudinal Gradients –              there was little available data and analysis
    Gravel should not be used in low                on the engineering performance and
    rainfall situations (< 1,000mm/year) on         deterioration of gravel roads. In the light
    longitudinal road gradients of more             of increasing speculation as to the long
    than 6%. In medium rainfall areas               term cost-effectiveness of gravel surfacing
    (1,000 – 2,000 mm/year) gravel loss by          in many locations in Vietnam this
    erosion will be high on gradients of            knowledge gap required urgent attention.
    more than 4%.                                   This was particularly important in view of
•   Adequate maintenance cannot be                  the large investments planned for
    provided – Gravel is a high                     expanding the rural road network for the
    maintenance surface requiring timely            purpose of rural development.
    both routine reshaping/grading and              Key Issues
    expensive periodic re-gravelling to
    replace surface material losses.                Material loss was considered to be the
                                                    principal issue in the RRGAP survey,
•   Sub-grade is weak or soaked (flood              partly due to its substantial impact on
    risk).                                          periodic maintenance needs and costs. The
•   Gravel           deposits            are        RRGAP was designed as a one-off
    limited/environmentally sensitive –             condition survey; hence although material
    Gravel is a natural and finite resource,        thickness was measured it had to be related
    usually occurring in limited quantities.        to design thickness to gain an estimate of
                                                    loss rather than by exact measurement.
Even in simple combinations of some of
                                                    The use of DCP profiles aided in the
the above factors, gravel can be lost from


                                              -4-
interpretation of material thickness              b. . The overall visual assessment data
measurements.    Material loss  was               indicated a composite road performance
                                                                model       comprising     the
                                                                differential           “spot”
                                                                deterioration     of     short
                                                                critical lengths separated by
                                                                lengths of road in better
                                                                condition.      This      spot
                                                                deterioration model was
                                                                indicated for around three
                                                                quarters of the roads
                                                                examined. In addition to
                                                                which the detailed material
                                                                loss data indicates an
                                                                overall general deterioration
                                                                of the entire road length.
                                                                 Material Characteristics
calculated in millimetres of material lost        There is a significant variability in the
per year.                                         nature and performance of the materials
Erosion was seen as a key cause of road           being used as unsealed road surfaces in
deterioration, causing the formation of           Vietnam. The material loss for the RRGAP
surface rills and gullies and increased road      sites was analysed for each of the seven
roughness conditions. Potholing and               principal material groups. The key
rutting were also selected as suitable            material related issues to arise out of this
deterioration indicators.                         examination are:

Material loss trends were evaluated by            a. The naturally occurring laterite, hill
examining the loss over a large number               gravel and alluvial gravels have a high
and range of sites. Gravel loss of                   number of sites (>60%) with greater
20mm/year was selected as the limiting               than 20mm/yr material loss. The
figure for road sustainability. This level of        implication is that these materials are
loss allows for 100mm of gravel to be lost           not suitable for use as an unsealed road
over a 5 year life without re-gravelling and         surface within the majority of Vietnam
can be considered a maximum loss figure              road environments. Similar comments
for road management sustainability in an             also apply to graded crushed stone as
environment where timely periodic                    an unsealed surfacing material.
maintenance, including re-gravelling, is          b. Where natural materials have been
not the normal practice due to a range of            mixed with additional crushed rock,
constraints.                                         weathered rock, or alluvial gravel and
Key issues with respect to the RRGAP                 cobble, the material loss figures show a
material loss and erosion data are as                distinct improvement.
follows:                                          c. Coarse non-graded stone surfacing
a. Overall material loss figures indicate            performs significantly better than other
   that around 58% of the surveyed sites             options in terms of material loss.
   were       suffering       unsustainable          However, it does suffer significantly
   deterioration, while 28% were losing              from surface erosion of fines, leaving a
   material at twice the sustainable rate.           rough surface susceptible to localised
                                                     deterioration.



                                            -5-
d. The natural gravel-stone mixtures also         In general terms Vietnam is a high rainfall
    have lower than average material loss,        environment       with    intense     storm
    but, as with the non graded stone, they       concentrations, and hence very high
    also appear to have a higher than             erosion potential. This undoubtedly has an
    average erosion/roughness potential.          impact on the deterioration of the unsealed
                                                  rural roads in Vietnam.
Terrain and Gradient
                                                  Conclusions and Recommendations
The impact of terrain indicates that erosion
increases significantly between 4% and            The RRGAP data indicate that it is likely
6% road gradient. It has been commonly            that over 50% of the unsealed rural road
acknowledged that gradients above 6-8%            network is either unsustainable in terms of
are not usually suitable for gravel               material loss or contains significantly
surfacing, however the RRGAP data                 deteriorating road sections. There are key
suggest that, for some materials at least,        factors that could be addressed to improve
this limiting figure should be lowered to         their condition and sustainability. These
4% for the high rainfall environments in          are:
Vietnam.                                          a. Funding/resourcing               and
Construction                                         implementation of appropriate routine
                                                     and periodic maintenance.
Good     drainage     is     considered     a
fundamental aspect of road engineering in         b.    Construction of additional side ditches
almost all relevant guidelines and design              to ensure that the road surfaces can
manuals. In a high rainfall country such as            effectively shed rainwater from the
Vietnam this aspect of road construction               road and disperse it satisfactorily.
should have a particularly high priority.         c.    Sealing of appropriate road links. In a
The RRGAP survey has, however,                         resource constrained environment, a
indicated that drainage, in the form of side           spot     improvement       strategy   of
ditches and carriageway run-off capacity               selectively treating problematic lengths
has not been given sufficient priority either          within a road link should be considered,
in construction or in maintenance in the               e.g. sections liable to flooding or with
Vietnam rural road network. The effects of             steep gradients.
poor drainage on road performance are
indicated by the impact it has on potholing       d. Improve the evaluation of the correct
and erosion.                                          usage of local gravel materials in rural
                                                      road programmes in Vietnam. It is now
Maintenance                                           recognised that a key objective in
Maintenance is a key factor for the                   sustainable road construction is to
sustainability of gravel roads. Gravel is a           properly match the available material
low-cost, but high-maintenance surface.               to its road task and local environment
The RRGAP data, indicates that adequate               and greater use should be made of
maintenance is not being achieved on the              adapting local non-standard materials
large majority of RT1 & RT2 roads.                    within appropriate designs.
Gravel roads suffering more than 20mm/yr          e. Gravel can only be considered as a
of material loss without appropriate                 serious viable surfacing option for
maintenance are largely non-sustainable              Vietnam rural roads on engineering
beyond 4-5 years and may well deteriorate            and economic grounds under the
at a significantly greater rate in some in           following conditions:
sections within that timescale.
                                                       i. Where specified quality material is
Climatic Effects                                          locally available in sufficient
                                                          quantities both for construction and


                                            -6-
       maintenance (probably within               c. Composite construction should be
       10km of the road). A realistic                considered as a strategy in future rural
       assessment of the likelihood of               road programmes. This involves the
       routine and periodic maintenance              construction of different surfacing
       being carried out should be                   options along a road link in response to
       included in the whole life costing,           differing environment impacts.
       including     the    risks     and         d. There is a clear requirement to make
       consequences      of    inadequate            local road authorities, contractors and
       maintenance.                                  local consultants more aware of the
   ii. Where road gradients are less than            importance of quality control and to
       4% in medium rainfall areas (1,000            place more emphasis on effective and
       – 2,000 mm/year). Gravel will                 contractually empowered construction
       probably be unsustainable at any              supervision of rural road projects.
       gradient for higher levels of rainfall
                                                  3.     Low Cost surfacing
   iii. Where adequate drainage (crossfall,       Many communities are denied road access
        side and dispersion) can be               due to the condition of the road during the
        guaranteed.                               rainy season. Poor quality pavement
   iv. Where adequate quality assurance           materials and subgrade conditions make it
       controls are in place for                  impossible to traverse the road. This
       construction supervision to ensure         usually occurs in low lying swampy areas
       contract     and      specification        and on steep gradients, where traction is
       compliance.                                drastically reduced.
   v. Where an appropriate maintenance            In order to address these specific problems,
      regime can be guaranteed as part of         DfID has funded research into alternative
      a whole-life construction and               pavements using local resources and
      maintenance specification.                  materials. These pavements, although
                                                  more expensive to construct provide year
   vi. Where flooding is only a minor
                                                  round access and lower long term (life
       local occurrence.
                                                  cycle) costs. In environmental terms they
   vii. Where traffic is below 200 motor          also reduce the reliance on increasing
        vpd equivalent.                           scarce gravel deposits by removing the
Apart from assessing gravel performance           need for frequent re-gravelling of the
the RRGAP has raised other important              problem sections and reducing erosion
issues, such as:                                  which often affects adjacent land.
                                                  Research has been conducted in Cambodia,
a. The investigations have indicated the          Vietnam and Lao PDR as detailed below.
   effectiveness of unsealed stone
   macadam in providing a sustainable
   surface/road-base, albeit with high            Cambodia
   surface erosion or roughness penalties.
                                                  Pavement trials were conducted in the area
b. Other techniques utilising natural stone,      of Puok District Market in Siem Reap
   without bitumen or cement binder,              Province. Previously the access roads to
   could have superior performance to             and roads around Puok Market itself had
   gravel, but with reasonable initial costs      been surfaced using the laterite, which has
   and lower maintenance liabilities.             been applied to many tertiary and sub-
   These surface options include hand             tertiary roads in Cambodia. The need for a
   packed stone and cobble stone paving.          more durable wearing surface was
                                                  recognized by the need for continuous


                                            -7-
maintenance of laterite surfaces and the         effect of injecting more of the road works
associated strain on resources. This             expenditures into the local community
became more apparent following excessive         through employment, use the of locally
flood damage during the exceptionally            supplied and processed materials and local
high intensity rainfalls in year 2000.           enterprises.
The higher traffic volume in the area of the     Ten sections of alternative paving were
market further compounded the need. The          constructed at Puok Market, under a
suitability of laterite as a wearing course      cooperation initiative between an ILO
decreases with increase in traffic volume.       Project, Ministry of Public Works &
Laterite loss has been found to increase         Transport and Ministry of Rural
almost exponentially with increases in           Development, Cambodia.. Two local
traffic volume. Furthermore the economic         contractors,     using     the   appropriate
viability of laterite as a wearing course        equipment and the optimum input of local
becomes increasingly dubious with the            unskilled and skilled labour, constructed
increase in haulage distance.                    the trials in mid year 2002. The aim of the
                                                 paving trials was to investigate and
A further consideration is the dust problem
                                                 demonstrate the construction of a range of
associated with laterite, especially in an
                                                 paving techniques as an alternative to
area of high population density such as
                                                 gravel/laterite, suitable for secondary and
Puok, there is a need to reduce the amount
                                                 minor roads using local-resource-based
of dust because of health problems, which
                                                 techniques wherever possible. The
may result in the local community. In an
                                                 pavements constructed included four basic
area such as Puok market where there are
                                                 road bases (water bound macadam, sand-
many food vendors and restaurants large
                                                 aggregate, crushed-stone and laterite),
volumes of dust represent a serious
                                                 three basic surface treatments (double chip
hygiene problem with foodstuffs being
                                                 seal, single chip seal, sand seal), bamboo
contaminated daily.
                                                 reinforced concrete pavement, dressed
Although laterite has a relatively low           stone pavement and hand-packed stone.
initial cost, ongoing periodic maintenance
                                                 The principal lessons from the Puok
requirements are considerable, even more
                                                 Market trials were:
so when the traffic volume exceeds 50
four-wheeled vehicles per day as is the          •       Rural road design in Cambodia is
case for Puok. Furthermore, laterite is a        particularly challenging and the past
finite non-renewable resource. Such were         simplistic and largely partially informed
the economic, social and environmental           approach to rural road provision can no
issues, which led to alternative surface         longer be tolerated or afforded in a
options being considered for the                 severely resource constrained environment.
rehabilitation of the roads around Puok          Factors of traffic and vehicle loading, local
Market.                                          materials availability, local resource use
                                                 technologies,       subgrade      conditions,
Under the DfID funded Knowledge and
                                                 maintenance regime must be carefully
Research      (KaR)     programme       and
                                                 considered in developing the appropriate
subsequent      SEACAP       8      Project,
                                                 construction and maintenance approach.
investigations were carried out and
guidelines developed on alternative low          •   Gravel/laterite should   be        used
cost rural road surfaces, which in                   selectively,    as     per          the
appropriate circumstances will have lower            recommendations above.
whole-life-costs    than    gravel.    The       •   There is a substantial range of
alternative surfaces can also have better            alternative paving options with better
local resource use attributes; with the              whole life cost and social benefits than


                                           -8-
    gravel/laterite.   These    can     be           concrete. The technique uses more
    constructed by small scale contractors           local resources.
    with limited equipment resources and         •   Steel Reinforced Concrete - To be used
    using local labour. Some paving types            as a comparison control for BRC.
    are more suitable for heavy vehicle
    overloading or a poor maintenance            •   Concrete Bricks - These have good
    regime.                                          load spreading properties, especially
                                                     on low strength subgrades. They are
                                                     re-usable if road base failure occurs.
Vietnam Rural Road Surfacing Trials                  The technique is suitable for small
                                                     scale local concrete brick production
The purpose of this programme, was to
                                                     by contractors or communities.
find out appropriate types of road
pavements for each of the variant regions        •   Bitumen/Emulsion         Seals       on
in Vietnam. Apart from the traditional               waterbound or dry bound macadam, or
pavements such as brick, hill gravel,                lime/cement/emulsion stabilised soil.
laterite, boulder, crushed stone, bitumen            These are a more efficient use of
sealed macadam, cement concrete, etc. the            bitumen compared to traditional
trial programme also covered other types             techniques. They represent good
of surfacing/paving, in consideration of the         protection of investment in roadbase
use of in situ and local materials, simple           materials and scope for labour-friendly
equipment and local labour, in order to              application using bitumen emulsions.
minimize construction costs and routine          •   Fired Clay Brick Paving.        Brick
maintenance         requirements,       and          technology is well established for
environmental pollution effects.                     house building use and good quality
The results of these trials were used in the         bricks are obtainable from small scale
follow up projects, supplement MOT‟s                 production using rice husk (a
rural road design and construction related           commonly available waste product), as
procedures and regulations, in order to              well as coal fired kilns. Bricks can
utilize investments made by the                      have a very high local labour content
Government, local governments, local                 with most costs recycled in the
people and international donors in an                community. There are very low
effective way, contributing to the                   transport costs and minimal haulage
Government‟s poverty reduction strategy.             damage to other roads when the kilns
                                                     are located close by
The options used included:
                                                 The RRST-II programme was an important
•   Dressed Stone - local skills in stone
                                                 step in the roll out and mainstreaming of
    cutting and dressing are established in
                                                 sustainable and appropriate rural surfacing
    some communities. Excellent quality
                                                 solutions. The scientific and engineering
    stone is available in some locations
                                                 objectives may be summarised as follows:
    and suitable for this use. The technique
    has a very high local labour content so      •   Trialing        of          alternative
    that a large proportion of the                   surfacing/pavement options within a
    construction expenditures is re-cycled           range of Vietnam road environments,
    in the local community with income           •   Construction trialing options under
    benefits.                                        longer-length, standard construction
•   Bamboo Reinforced Concrete (BRC) -               conditions,
    There are expected to be cost and            •   Trialing a knowledge-based selection
    transport savings over steel reinforced          process for rural road designs which
                                                     included a more detailed weight being


                                           -9-
    given to road environment factors such                under the present maintenance
    as of sub-grade condition, topography                 environment leads to poor levels of
    and hydrology.                                        accessibility, high transport unit costs
                                                          and constraints to rural development.
•   Integrating appropriate options from
    into the provincial road authority‟s              The monitoring of these trial pavements is
    selection, design and supervision                 still ongoing and the results will be
    processes.                                        provided in future reports.
•   Wider involvement of local consultants            Lao PDR
    and contractors in techniques and                 SEACAP 17 Project was implemented to
    practices associated with sustainable             identify cost-effective        methods     of
    rural road design and construction.               improving all-year access to the rural poor
During the project, a small number of new             through low-cost locally resource based
options investigated. These were:                     improvement of problematic lengths of
                                                      road leading to sustainable rural access
•   Un-reinforced Concrete
                                                      roads. The project has been implemented
•   Cobble Stone Paving                               in conjunction with the ADB Northern
•   Quarry-run sub-base and shoulders                 Economic Corridor Project (NEC) to carry
                                                      out research on a group of rural access
•   Sealed shoulders                                  roads in Houay Xai District of Bo Keo
A number of important issues are worth                Province. The approach adopted was to
noting in relation to the costing, design             replace the standard gravel surfacing with
and eventual interpretation of the trials.            a „trial pavement‟ at specific locations
These are listed below.                               along the access roads. The pavement
                                                      types selected for the trials developed from
•   The selection and design criteria for             similar projects in the region and
    the “Local” trial roads were based                worldwide as follows:
    more on local experience and current
    standards than on surveyed road                   •      Bamboo Reinforced          Concrete,
    environmental factors such as sub-                described above.
    grade strength, traffic and material              •   Otta Seal, this surface comprises of a
    properties.                                           layer of binder followed by a layer of
•   Assessment        of     the      existing,           aggregate that is rolled into the binder
    predominantly gravel, surfaces of the                 using a roller or loaded trucks. It is
    trial roads indicated that they were                  different to surface dressing in that an
    constructed with materials generally                  'all in' graded gravel or crushed
    below official MoT standard. The costs                aggregate is used instead of single
    proposed by the Provincial Road                       sized chippings.
    Authorities and Local Consultants for             •   Geocell,        manufactured    plastic
    gravel options, whilst in accordance                  formwork is used to construct in-situ
    with current norms, are unrealistically               concrete paving. The plastic formwork
    low and reflect only the cost of                      is sacrificial and remains embedded in
    acquiring nearby gravelly material                    the concrete.
    irrespective of its quality, together with
    subsequent construction under minimal             •   Hand Packed Stone, this surface
    supervision. As the above mentioned                   consists of a layer of large stones into
    research indicates, use of such sub-                  which smaller chips are packed.
    standard material results in very poor                Remaining voids are filled with sand
    performance of the road surface and                   or gravel to form a strong and semi-
    high maintenance liabilities, which                   impervious matrix.


                                             - 10 -
•    Mortared Stone, this surface consists            required to provide access. This wastes
     of a layer of large stones, placed               large portions of the available budget often
     closely together to form a tight surface.        for works that are not actually required to
     The voids are filled with mortar to              provide basic access to communities. In
     form an impervious layer.                        many cases good sections of road, which
                                                      are passable all year round, are „improved‟
•    Concrete Paving Blocks, the blocks are
                                                      when they could in fact be left in their
     precast in moulds and then laid side by
                                                      existing condition for longer periods of
     side on the road. Gaps between blocks
                                                      time.
     are filled with fine material to form a
     strong and semi-impervious layer. A              The resulting construction also is wasteful
     variation of this is to use Fired Clay           of limited natural resources. There is
     Bricks where these are available.                therefore the need to change the thinking
                                                      on road improvement and rehabilitation to
•    Engineered Natural Surface, this
                                                      concentrate on repairing or improving
     construction is used where the existing
                                                      sections that are critically restricting all
     subgrade material comprises natural
                                                      year access. The spot repair/improvement
     gravel with the same characteristics as
                                                      approach would include treatments such as
     the pavement layer.
                                                      •   a an appropriate design on steep slopes
The work was completed in September
                                                          or soft subgrades,
2007. On completion of the trial section
monitoring will be continued over the long            •   spot re-gravelling on short sections,
term and will contribute to the database of           •   culverts/drifts on streams where heavy
knowledge along with the results of                       rain might restrict access for a few
similar trials in Cambodia and Vietnam.                   hours only.
4.      Spot Repairs and Improvements                 In SEACAP 17, as discussed above, trial
What is meant by „access‟ for rural                   pavements have been constructed on
communities has to be clearly defined. The            problematic sections of rural access roads.
rural population needs access to essential            It will demonstrate the use of more robust
services such as health, education, markets           pavements on steep gradients and soft
and government services. However, it is               subgrades to ensure all year access.
not always necessary for communities to               In Cambodia, under the KfW funded
have 24 hour, 365 day a year access and               Tertiary Road Improvement Project, spot
some short term delays, such as 1 day due             repairs and improvements are being
to swollen rivers, can be acceptable.                 carried out under the annual maintenance
Further, the communities do not                       programme. Roads have been identified
necessarily need roads designed to carry              which are mostly in reasonable condition,
large volumes of traffic at high speeds.              but have short badly damaged sections
Often sections of road are trafficable in all         which prevent access. These include
weathers and only require minor                       collapsed culverts, minor embankment
maintenance works such as side drain                  failures and sections badly damaged by
cleaning, bush clearing etc, which is well            flooding. Adoption of the spot repair
within    the    capabilities    of     local         approach has resulted in a much larger
communities. A road might also be                     portion of the rural road network being
unusable for the whole or part of the year            made accessible than would have been
because of one location blocking access.              possible through a normal periodic
                                                      maintenance or rehabilitation programme
It is common practice for projects to re-
gravel or rehabilitate the entire length of a         under the limited budget available. In an
                                                      area where good quality materials are
road without really considering what is


                                             - 11 -
difficult to obtain, this approach has also          hillsides, which if crushed can be
minimised the use of these scarce                    improved to an adequate quality material
resources.                                           for use in road pavements or concrete
                                                     works. These deposits are often too small
The following simple strategy can be
                                                     for setting up a permanent quarry site.
considered by road agencies for
maximising the impact of their budgets                In SEACAP 17 Project in Lao PDR the
and minimising the use of local material             contractor was importing good quality
resources and engaging with the local                pavement materials for the trial sections
communities through each step:                       from a commercial quarry 50km from the
                                                     start of the nearest access road. For
•    Identify problem spots.
                                                     community based works on limited
•    Determine     user   needs,   acceptable        budgets, this would be prohibitively
     delays etc.                                     expensive. A preliminary investigation
•    Identify local material sources.                found six sources of good quality materials
                                                     in the project area. However, the quantities
•    Select appropriate     technology    for        are relatively small and quality of the
     intervention.                                   uncrushed material is not suitable for use..
•    Prepare cost estimates and budget.              Nor is it economical to haul to nearest
                                                     large crusher and back.
    Implement works.
                                                     An assessment of the size of the deposits
5.      Mobile Stone Crushers                        suggests a total quantity of 230,000 cubic
Rural road construction and maintenance              metres is available. The pavement
requires large quantities of gravel. The             dimensions for the access roads are 4.5m
options available are to use commercial              wide with 200mm pavement thickness,
quarries, often with long haul distances, or         which requires 900 cu.m of aggregate per
local „as dug‟ materials.                            kilometer. The identified sources could
                                                     therefore provide pavement materials for
Large scale quarries usually long distance
                                                     approximately 255km of such access roads,
from construction site. Large quarries have
                                                     with very short haul distances, if they
associated environmental problems. Long
                                                     could be improved.
haul distances along local roads increase
costs, damage the roads, which were not              Mobile crushers are a cheap and easy way
designed for the heavy axle loads, and               to process small local deposits of materials.
cause dust and safety problems through               They are easy to transport and set up and
villages. This can result in more money              require minimal skills for their operation.
being spent on transport than on the road            On the UNOPS programme in Afghanistan
itself.                                              a mobile crusher was used with a capacity
Communities and local contractors usually            of 4 cubic metres per hour for granite (this
do not have the means of producing good              rate would be much higher for softer stone)
quality materials and often simply make              imported from Bangladesh at a cost of
do with what is available „as dug‟. The              about US$6,500 in country. This came
quality of these materials is often                  with spare jaw plates and the parts are
unsuitable for robust pavements and                  readily available in country and Afghans
durable surfaces. They often exhibit high            are able to work with these machines.
plasticity and poor grading, resulting in            While Afghanistan may be a country with
short life and premature failure of the              a lot of stone, sometimes haul distances
pavement.                                            did go up fairly high for quarried material
In many circumstances there may be small             but there is almost everywhere river gravel
gravel deposits, either river beds or from           available. In this case this could be


                                            - 12 -
extracted,      without     large     scale         vegetation becomes a major structural
environmental damage or causing soil                component of the soil bioengineering
erosion since river flood plains are often          system.
very large. The cruched material is good            Nonliving      approaches      use     rigid
for use in road base, sub-base and concrete         constructions, such as surface armoring,
aggregates.                                         gravity retaining walls, and rock buttresses.
This appropriate form of intermediate               Vegetation can be used in conjunction
technology can be introduced where                  with nonliving structures to create
materials are abundant but do not meet              vegetated structures. Vegetation enhances
specification without minor processing. A           the structures and helps reduce surface
large cost saving can be affected through           erosion, but usually does not provide any
establishing this easily transportable              major reinforcement benefits.
equipment is used by small scale                    Soil bioengineering uses particular
contractors.                                        characteristics of vegetative components
6.     Bio Engineering                              and integrates specific characteristics of
                                                    structures with vegetation. The resulting
Background
                                                    systems and their components have
Soil bioengineering, in the context of slope        benefits and limitations that need to be
stabilization, combines geotechnical, and           considered prior to selecting them for use.
civil engineering with, biological, and             Herbaceous vegetation, especially grasses,
ecological concepts to arrest and prevent           offers long-term protection against surface
shallow slope failures and erosion. Basic           (water and wind) erosion on slopes. It
approaches to slope protection and erosion          provides only minor protection against
control can be divided into two general             shallow mass movement. Vegetation helps
categories:     living    and    nonliving.         to prevent surface erosion by:
Frequently, living and nonliving measures
                                                    •   Binding and restraining soil particles in
are combined to form a system.
                                                        place;
The living approach, which uses live plant
                                                    •   Reducing sediment transport;
materials, can be further divided into two
specific categories: vegetative plantings           •   Intercepting raindrops;
and soil bioengineering. Vegetative                 •   Retarding and controlling velocity of
plantings are conventional plantings of                 the runoff;
grasses and shrubs used to prevent surface
erosion. Soil bioengineering utilizes live          •   Enhancing and maintaining infiltration
plant parts to provide soil reinforcement               capacity.
and prevent surface erosion.                        Herbaceous species are almost always
In soil bioengineering systems, the                 used     in    con-junction  with    soil
installation may play the major structural          bioengineering projects to add protection
roles immediately or may become the                 against surface erosion.
major structural component over time.               More deeply rooted woody vegetation
Live staking, live fascines, brush layers,          provides greater protection against shallow
branch packing, and live gully repair are           mass movement by:
soil bioengineering techniques that use
stems or branch parts of living plants as           •   Mechanically reinforcing the soil with
initial and primary soil reinforcing and                roots;
stabilizing material. When these vegetative         •   Depleting       soil-water      through
cuttings are placed in the ground, roots                transpiration and interception;
develop and foliage sprouts. The resulting



                                           - 13 -
•   Buttressing and soil arching action             component is to give the vegetation a
    from embedded stems                             better chance to become established. It has
                                                    been shown in slope reconstruction
Civil engineering structures also play a
                                                    projects that soil bioengineering systems
critical role in the establishment of
                                                    can withstand heavy rainfalls immediately
vegetation on steep slopes or in areas
                                                    after installation. Even if established
subject to severe erosion. They may make
                                                    vegetation dies, the plant roots and surface
it possible to establish plants on slopes
                                                    residue may continue to play an important
steeper than would normally be possible.
                                                    protective role during reestablishment.
Structures stabilize slopes during the
critical time for seed germination and root         Once vegetation is well established on a
growth. Without this stabilization,                 soil bioengineering project, usually within
vegetative plantings would fail during their        one growing season, it generally becomes
most vulnerable time.                               self-repairing by regeneration and growth
                                                    and requires little maintenance. However,
Materials Structures can be built from
                                                    newly installed soil bioengineering project
natural or manufactured materials. Natural
                                                    will require careful periodic inspections
materials, such as earth, rock, stone, and
                                                    until it is established. Established
timber,     usually     cost   less,    are
                                                    vegetation is vulnerable to trampling,
environmentally more compatible, and are
                                                    drought, grazing, nutrient deficiencies,
better suited to vegetative treatment or
                                                    toxins, and pests, and may require special
slight modifications than are manufactured
                                                    management measures at times.
materials. Natural materials may also be
available onsite at no cost.
Soil bioengineering systems generally               Bioengineering in Southeast Asia
require minimal access for equipment and            The use of bio-engineering has been
workers and cause relatively minor site
                                                    introduced successfully in many situations.
disturbance during installation. These are          Particular success has come from its
generally priority considerations in                applications to low-traffic, low-cost hill
environmentally sensitive areas, such as            roads in Nepal. Research in Vietnam has
parks, woodlands, riparian areas, and               also demonstrated significant potential
scenic corridors where aesthetic quality,           Other similar areas in South and South-
wildlife habitat, and similar values may be         east Asia where bio-engineering has been
critical                                            used successfully are Cambodia, the north-
Soil bioengineering measures should not             eastern states of India, Kashmir and
be viewed as a panacea or solution for all          Bhutan.
slope failure and surface erosion problems.         With the exception of Cambodia, all of
Soil bioengineering has unique attributes,          these areas are in an approximately similar
but is not appropriate for all sites and
                                                    eco-climatic band running east-west along
situations. In certain cases, a conventional        the sub-Himalayan zone that straddles the
vegetative treatment (e.g., grass seeding           Tropic of Cancer. Combined with broadly
and hydro mulching) works satisfactorily            similar material and slope characteristics
at less cost. In other cases, the more              resulting from a shared geological history,
appropriate and most effective solution is          this leads to a potential for adopting
structural retaining system alone or in             similar preventative maintenance strategies.
combination with soil bioengineering.
                                                    Outside the region, successful applications
Soil bioengineering systems are strong              of bio-engineering have been made
initially and grow stronger with time as            particularly in the Caribbean and Central
vegetation becomes established. In some             America, and under rather different
instances, the primary role of the structural


                                           - 14 -
climatic conditions on the huge networks             likely scale of resources available for
of forest service roads in the USA and               future maintenance.
Canada.
                                                     7.     Conclusion
Slope stability trials are being conducted           Providing and maintaining access to rural
in Lao PDR under the SEACAP 21 project.              communities does not necessarily have to
Initial findings during the preparation of           negatively impact on the environment.
SEACAP 21 in Lao PDR have shown that                 Careful use of scarce resources and
bio-engineering measures alone will not be           providing environmentally sustainable
adequate for the scale of many of the slope          solutions to access problems can minimise
stability problems found on the roads. For           the undesirable effects and contribute to
this reason these require a significant scale        environmental preservation.
of geotechnical engineering structures in
order to safeguard roads in particularly             As discussed in this paper, gravel,
unstable sections.                                   especially good quality laterite in the
                                                     lower Mekong region, is increasingly
There are two main types of failure from             difficult to locate resulting in the use of
the engineering perspective. The first, and          poor quality substandard material in road
by far the most common (upwards of 200               construction. Rapid deterioration of the
incidences on the project studied road), is
                                                     gravel pavements results in the need for
typified by small failures above and below           even more material to rehabilitate the road
the road. The failure mechanism appears              in order to maintain access. With the
to be due to erosion caused by surface               constant use of these poor quality
water running down the slope and/or,                 materials, the communities and road
saturated failure through the poorly                 authorities are locked into an unending
drained soil passing its liquid limits on an         cycle of repair with a constant drain on
over-steep artificial cut.                           local material resources.
The second type of failure is more serious.          Similarly, the repair of frequent landslides
It is represented by relatively deep-seated          by removing material and cutting back
failures along a rotational shear plane, and         slopes does not solve the problem, which
can result in the loss of the road edge, or          returns year after year with the consequent
displacement of the road itself. Fortunately         increasing environmental damage.
they appear to be absent in the problems
found in the SEACAP project road.                    Traditional rural road rehabilitation
                                                     programmes use large quantities of gravel,
In general the first of these types of failure       often of marginal quality, which rapid
can be resolved, or even prevented,                  erodes and requires replacement. Large
through the judicious use of slope drainage          scale quarry operations to feed these
and surface protection using bio-                    programmes        cause    environmental
engineering. An important feature of these
                                                     problems in their operations and through
interventions is that they tend to involve           long haul transport through rural
labour intensive works that yield high               communities. Gravel is an increasingly
employment opportunities for local people.           scarce resource and governments and
The second type usually requires complex             donors must look at ways of reducing its
analysis and may require substantial                 use while at the same time managing their
geotechnical engineering structures, with            limited budgets. Similarly, cuttings in
bio-engineering measures limited to                  mountainous areas must be stabilised as
protection of the ancillary earthworks. In           part of the construction and maintenance
some cases these works are possible using            programmes and included in the scope of
relatively low cost measures, as                     projects
appropriate to the local economy and the


                                            - 15 -
These strategies are being investigated and
mainstreamed through the DfID SEACAP
programme involving bioengineering
techniques, spot repairs, the use of robust
pavements on problematic sections and the
exploitation of small gravel sources can
address and help solve these problems.




                                          - 16 -
Reference:
1. Experiment of Pavement Suitable for
   Rural Transport. Dr Jasper Cook -
   Robert Petts Bach The Dung - Pham
   Gia Tuan Intech - TRL - WSPI – TEDI.
   Transport Journal Volume 5/2004
2. Rural Road Gravel Assessment
   Programme (SEACAP 4). Module 4
   Final Report, 2005. Intech-TRL.
3. Cambodia Low Cost Surfacing Trials
   (SEACAP 8) Draft Final Report, 2006.
   Intech-TRL
4. Rural Road Surfacing Research
   (SEACAP 1) Phase III for MoT
   Vietnam RRST-II , Module 1, Final
   Report (Design). 2006. Intech-TRL
5. Local     Resource       Solutions     to
   Problematic Rural Road Access in Lao
   PDR (SEACAP 17) Module 1 Report,
   2005. Roughton International.
6. Slope Stabilisation Trials on Route No.
   13 North in Lao PDR (SEACAP 21)
   Project      Preparation      Document.
   Roughton International, 2004.
7. Engineering Field Handbook. United
   States Department of Agriculture
   Natural     Resources      Conservation
   Service.
8. Global       Transport       Knowledge
   Partnership. www.gtkp.org
9. DfID Transport Links. www.transport-
   links.org
10.     Cambodia National Council of
   Transport                  Practitioners.
   www.cnctp.info




                                           - 17 -

								
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