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In 1997, the Society of Chief Officers for Transportation in Scotland, SCOTS,
published details of work it had been undertaking to assess level of funding to
Local Authorities in Scotland, and how this level of funding compared with the
funding needs at the time.

The report, produced by a group chaired by Dr Bob McLennan, arrived at the
following conclusions:
 The basis of evaluating needs and allocating monies was wholly
 There was no recognition of the best value approach of planned
    maintenance in terms of the whole life cost
 There was a major funding gap between what was provided to Council in
    the form of grant for road maintenance and what was needed from a whole
    life cost perspective
 There was evidence that Councils were not spending all of the grant
    funding for road maintenance on that activity
 Councils were giving higher priority to winter maintenance than other road
    maintenance activities
 Important capital projects were having to be funded from reducing capital

The report methodology was to look at the level of spending provision, both at
the initial grant funding level and the actual allocation by authority, and to
compare this with realistic whole life cost needed to maintain the carriageways
and street lighting.

In 2002, SCOTS embarked on a jointly funded project to gather machine
based condition survey data for all local authority public roads in Scotland.
This study was groundbreaking in that it involved all authorities, it gathered
gathering comparable data on the condition of the carriageway and the
technology in use was relatively untried in the UK. Having started this process
of gathering information that would give a clearer indication of the condition of
Local Authority roads, SCOTS members were subsequently of the view that
they wished to update the 1997 report utilising the data available from


What is the overall asset?
During the course of the assessment, much consideration was given to what
actually constitutes ‘the asset’. The earlier study in 1997 compared the
funding awarded to local authorities with the whole life cost for road
infrastructure. However, the working group considered there was a need to
extend the scope of the previous work to include parts of the asset that were
now coming under greater scrutiny, e.g. drainage, bridges and footways. For
this reason a catalogue of elements was developed. This included the
immediately identifiable parts of the infrastructure that the public would
recognise it, e.g. carriageway, footway, street lighting, and the unseen or
lesser elements that as a result of increased spending over the past 10 years
through central government targeted expenditure, have become more
apparent e.g. road related structures, drainage, intelligent traffic systems, and
enhanced quality of surfacing and street furniture.

Quantification of Available Information
It was immediately appreciated by the working group that not all authorities
would hold information on the condition of the entire infrastructure within their
responsibility. This may seem a little odd given that in most cases it will have
been the authority or its predecessors who would have built or managed the
network over many years. However, while there were some authorities had
detailed knowledge of what existed and what condition it was in, the majority
were not in this position, with some having very little detailed condition
information and having prioritised their increasingly stretched resources
towards works rather than on management systems.

In order to ascertain the situation across Scotland, a short questionnaire was
sent to all authorities seeking information on the data held and its quality i.e.
desktop assessment, visual surveys, detailed surveys along with any
estimated costs for repairs. The majority of authorities provided feedback to
the survey.

As each authority had agreed to contribute to the gathering of machine based
condition information for carriageways this was omitted from the
questionnaire. This would also allow the backlog of carriageway repairs to be
developed through the use of the results from the Scottish Road Maintenance
Condition Survey. This was therefore omitted from the questionnaire, however
there was to be a need to establish the costs of different treatments to allow
the overall backlog to be calculated.

The condition of road structures is updated on a regular basis by the bridges
working group of SCOTS. The intention therefore was to use the most up to
date figure from their work and to modify it to reflect any major works that had
been completed or had commenced since its calculation.


The final element in this category was street lighting. At a national level the
backlog of street lighting was being established by the Street Lighting Board,
a group created to consider issues relating to street lighting across the UK.
Since this work would produce an overall figure for the UK, and a
methodology for its calculation, it was agreed that this would provide a
suitable basis for the SCOTS calculation.

Establishing Family Groupings
While the survey had revealed that there was information available but that
significant gaps existed across authorities. How the information could be used
was therefore a key issue, especially where the information held by one
authority might not readily relate to an authority of quite different nature. The
group agreed that in order to make best use of the information, authorities
should had to be grouped on a like for like basis. This led to five groups being
established: Cities; Urban; Semi-Urban; Rural and Islands, defined as

Group                             Definition
Cities                            The four city authorities in Scotland
Urban                             An authority with>70% of its roads being classed as
Semi-Urban                        An authority with<70% but >30% of its roads being
                                  classed as urban
Rural                             An authority with <30% of its roads being classed as
Islands                           The three island authorities, with possible input from
                                  the Highland Council and Argyll and Bute Council as
                                  they had islands within their area of responsibility

The list of authorities within each group is set out in Appendix 1.

The groupings established had similarities with earlier work undertaken by
Audit Scotland in relation to refuse collection based on six groupings and
population dispersal, and were therefore felt to be on a sound footing.

This methodology also had many benefits to the calculation of an overall
backlog. It allowed direct comparisons to be made between authorities in the
group, especially where the backlog on a particular piece of the infrastructure
differed markedly between Councils. It also allowed comparisons to be made
between groups e.g rural and semi-rural on both the quality of repairs required
and the costs.


Role of the Groups
The groups were established to perform two key functions:

        To identify the costs of defined repairs to the different elements of the
         infrastructure e.g. carriageway treatments, footways etc.
        To compare the estimated backlog across the authorities in the group,
         developing estimates for those unable to provide information.

This process was important as it ensured that unusual quantities or costs of
outstanding defect could be challenged and amended to broadly reflect the
results from other group members.

An initial list of infrastructure elements and cost items was developed and
each group tasked with collating and developing an initial backlog calculation.
This list of items is set out in Appendix 2 and includes a table to identify costs
associated with the carriageways. During this stage it became clear that
some of these elements should not be collected, e.g. car parking, as these
tend to be addressed through wider corporate property portfolios or funded
through budgets other than those specifically related to roads infrastructure.

Even with a description of the method or item coverage, some of the items
proved difficult to assess and ultimately to compare across groups. One such
area was in regard to drainage. This is a vast area where most authorities
have little detailed knowledge of the condition of the infrastructure. In an
urban context the most obvious backlog is to deal with defective gullies.
However, in a rural situation the method of dealing with a drainage problem
could vary from location to location and it was therefore difficult to identify
backlog and costs.

Throughout the process the major recurring challenge has been to define
‘what constituted a backlog’. There has been an inclination in the past to look
at the life expectancy of an element of the infrastructure and to conclude that
there was a backlog exists if it is not replaced at the end of the specified time.
Clearly, while this may be appropriate if considerably larger sums of funding
are available for replacement, in a situation where there is limited funding,
there is a need to prioritise replacement. It is therefore not uncommon to
have parts of the infrastructure lasting well beyond its ‘theoretical’
replacement date.

In this exercise, for some elements the backlog is based on known condition
data. In others, where no data is available, it has been necessary to rely on
engineering judgement – some items, for example retaining walls, might face
sudden failure rather than display any evident steady deterioration. While it
was appreciated that this is not a whole life approach, it is a reasoned way
forward that reflects how Councils operate in stringent funding situations.



The Backlog Calculation
This part of the study utilised the information that had been collated in the
family groups and through other sources identified earlier in this report. For
this reason, this part of the report is split into two distinct sections relating to
the backlog for carriageways and for other associated infrastructure.

The Carriageway Backlog

Having gathered costs for various treatments of the carriageway, the results
from the Scottish Road Maintenance Condition Survey were used to calculate
the carriageway backlog. Details of how the information gathered is used in
working out a backlog can be found on the SCOTS web-site. The calculated
overall backlog at December 2004 is set out in Appendix 3.

The Associated Infrastructure
Having gathered information from each of the groups on the quantity of
defective infrastructure in each category and the average costs of repairs, it
was possible to build a preliminary backlog figure for each group. At this point
it was evident how important the family groupings had become. Not only did it
give a comparison between authorities in each group, but it also allowed
comparisons to be made across groups.

A quick comparison of the grouped road lengths, excluding the islands,
reveals that while there are considerably different overall, there is roughly the
same quantity of urban roads in each of the four groups (see table below).

Group                               Total Road Length (km)        Total Urban Road
                                                                  Length (km)
Cities                              4632                          4335
Urban                               4369                          3940
Semi – Urban                        10304                         5407
Rural                               21341                         4257

So while there may be little comparison between the groups for some areas
e.g. Intelligent Transport Systems, there were opportunities to compare
estimates for other items e.g. street lighting.

The methodology adopted has scope for incremental improvement that will
increase the accuracy of the estimates.


The Backlog

Based on the available information held by local authorities in Scotland, and
the information from the Scottish Road Maintenance Condition Survey Results
an updated calculation of the backlog of road maintenance repairs has been

At this point it is important to caveat the information provided below on the
backlog calculation.

The carriageway information is sourced from sound, repeatable mechanical
surveys, and estimates based on a consistent framework of costs for repairs.

However, in the absence of sound supported condition data for other
infrastructure, there is presently no robust and repeatable way of arriving at a
backlog for non-carriageway items. It has thus been necessary to take a
different approach based on engineering judgement. In some cases, the
estimated backlogs are based on relative comparison between groups,
authorities or elements, within an overall estimated target figure. For example
it is expected that the drainage backlog would be lower than footways but
greater than that for ITS, and signing and lining.

Many authorities will have reported locally on what they have assessed to be
their infrastructure backlog. It is likely that such assessments will have used a
different methodology to that adopted for this study.

To this end, it is not recommended that any estimate be derived of
individual authority backlog from the group figures below (other than
those relating to carriageways). The backlog should be treated solely as
a national / group figure based on a broadly consistent estimate of
needs rather than on theoretical life expectancy.

The following table sets out a summary of the backlog, and the split per group
with an indication of how the proportion was arrived at.


Infrastructure                 Cost                 Split per     Comments
                               (Millions)           group
Carriageway                    700                  1)167         From unit costs and
                                                    2)61          information on condition
                                                    3)209         of carriageways in
                                                    4)236         SRMCS (rounded down
                                                    5)27          to the 700M figure)
Footways/Footpaths             270                  1)95          Split based on initial
                                                    2)50          return from groups and
                                                    3)70          takes into account the
                                                    4)50          urban road length
Drainage                       60                   1)8           Split based on
                                                    2)7           approximately 50/50
                                                    3)15          urban / rural with costs
                                                    4)29          apportioned by group
                                                    5)1           length
Street Lighting                145                  1)34          Based on 1/6 of total for
                                                    2)31          England/Wales as
                                                    3)43          reported to transport
                                                    4)34          Select Committee
                                                    5)3           Split based on urban
                                                                  road length although
                                                                  could be further refined
                                                                  looking at geographic
                                                                  locations e.g. coastal
Structures                     160                  1)49          Includes bridges,
                                                    2)31          retaining walls, culverts,
                                                    3)43          safety fencing, high
                                                    4)34          mast lighting and
                                                    5)3           tunnels
                                                                  Split weighted to include
                                                                  major structures in cities
                                                                  e.g. Clyde tunnel
Others                         25                   1)6           Traffic lights, signs,
                                                    2)5           lining, etc
                                                    3)7           Split based on urban
                                                    4)6           road length
Sub Total                      1360
Add 15% On costs               205
TOTAL                          1565


The Next Steps

SCOTS members have contributed significant resources to the quantification
of this backlog assessment. However, having gone through this exercise
once, using data up to end of 2004, there are clearly lessons to be learned in
repeating the process. Such a calculation would be pointless if undertaken on
an annual basis as the process takes some time to gather the data.
Furthermore the ongoing survey of condition of carriageways through the
SRMCS, with results produced annually, would mean that the associated
infrastructure calculation becomes time consuming as the data is not so
readily gathered in a robust form.

From a SCOTS perspective, it is recommended that the following actions be
progressed in order to improve the quality and repeatability of the assessment
and to ensure the future robustness of the outcomes.

        The use of the ‘family grouping’ should be adopted as a means of
         representation in other aspects of SCOTS work. This would allow a
         spread of Councils to be involved and for ‘family groups’ to compare
         information for benchmarking purposes.

        To quantify the information held by authorities on the condition of their
         infrastructure. Given that some authorities are gathering condition
         information on an ongoing basis this may mean that those authorities
         will provide more robust data for the family group. It would also avoid
         authorities in the same group unnecessarily gathering the same
         information to the same detail thereby allowing the full data set to be
         collected from the group more quickly and efficiently.

        To investigate, along with others such as CSS and Scottish Executive
         details of whole life costs of various other parts of the infrastructure
         other than carriageways. Some work has been done in this area by
         authorities and this should be discussed more widely. It is understood
         that the Footways Group in CSS have undertaken such work in the

        To annually repeat the questionnaire and report undertaken by Audit
         Scotland on the costs of various activities for maintenance. This will not
         only allow benchmarking within the groups but also create
         transparency of increasing costs within the public sector for planned
         maintenance works.

        To develop and build on the exercise in order to allow a backlog figure
         to be calculated by end of 2007 with a report in place for 2008.


This task first appeared in the SCOTS business plan in 2003 and was
undertaken by the Infrastructure and Funding group of the Transport Policy
and Resources Committee.

It would not have been possible without the specific support of:

Charles Norman (Clackmannan Council)
David Rennie (Fife Council)
Douglas Hill (Angus Council)

Hugh Murdoch (Aberdeen City Council)
Chair of Infrastructure & Funding Group



East Dunbartonshire
East Renfrewshire
North Lanarkshire
West Dumbartonshire

East Ayrshire
East Lothian
North Ayrshire
South Ayrshire
South Lanarkshire
West Lothian

Argyll & Bute
Scottish Borders
Dumfries & Galloway
Perth & Kinross

Comhairle Nan Eilean Siar

                                                                                          APPENDIX 2

                             Carriageway Maintenance "Backlog" Questionnaire
                                                       Carriageway Maintenance Costs
Description                             A Class           B Class           C Class         Unclassified
                                    Urban     Rural   Urban     Rural   Urban     Rural   Urban     Rural
Ave width of carriageway (m)
Full Reconstruction (£ per sq m)

Average Depth
% of Network Treated by length

Overlay (£ per sq m)
Average Thickness
% of Network Treated by length

Inlay (£ per sq m)
Average Thickness
% of Network Treated by length

"Thin Surfacing" (£ per sq m)
% of Network Treated by length

Extra Over for Kerbing associated
with above works (per lin m)
Surface Dressing (£ per sq m)

% of Network Treated by length

C'Way patching (£ per sq m)
Total Expenditure
Edge strengthening (£ per lin m)

% of Network Treated by length

1.Please enter contract costs only. ie. exclude client and central support costs
2. Reconstruction defined as involving more than the replacement of surfacing (including regulating course)
3. While it is recognised that the extent of reconstruction may vary, insert typical rates for work undertaken
4. Thin surfacing" relates to the average rate which would be considered appropriate for each road category
5. Surface dressing to include costs of prepatching
6. Surfacing costs to include ancillary costs such as ironwork
7. If type of treatment is not applicable enter N/A


                            Additional Costs Associated with Carriageway
                                            TOTAL No/km No or Length   % defective   Rate   Know Costs
Footways/Footpaths             Poor
Road Drainage Poor
Street Lighting, Poor
ITS, Poor
Traffic Signs renewal

Car Parking Machines

Safety Fences

Bridges/Culverts, Ongoing
             Remedial works
Retaining Walls, Ongoing
Cycleways, Ongoing
Bus Shelters

Geotechnical Problems


Car Parks, Ongoing

Notes on Associated Items
1.Enter total length or number of particular piece of assest within Authority area
2. If detailed surveys are available then base on length or number
3. If no detailed information then estimate of percentage should be used
4. Enter average contract costs , i.e. exclude client and central support costs
5. If the overall backlog figure is known then insert in the known cost section.
6. Footways, Poor assume overlay and 50% rekerb. Bad assume full reconstruction and kerb replacement.
7. Drainage,Poor assume gully replacement including connection to surface water drain. Bad assume
renewal of gully connection and length of surface water drain. In rural context assume length of road over
drainage is required
8. Lighting, Poor assume column replacement. Bad assume column and cable renewal between columns
9. Bridges/Culverts, Ongoing assume maintenance to retain safe condition, Remedial assume work required
to bring up to acceptable standard including 40 tonne live load test
10. Traffic Signs , Renewal assume replacement of signs
11. Car Parking Machines assume life of 12 years is timescale when require replacement
12. Cycleways assume similar condition assessment to footways above
13.Bus shelters, assume when annual maintenance exceeds 25% of replacement cost, shelter be replaced
14. Car Parks assume similar assessment to carriageways
15. Safety Fences, assume replacement required when 5 year inspection identifies remedial working greater
than 20% replacement cost
16. ITS, assume poor to be units aged between 10-15 years and can be repaired, bad in excess of 15 years
where replacement required
17. Retaining Walls, assume ongoing where repair possible and renewal where reconstruction required


                                                                                                                                      APPENDIX 3
                     SRMCS - ( 2003/2004 ) Backlog Summary (Revised Dec 2004)
Authority                      Total       Expenditure Steady
                               Backlog     Yr 1- 10      > yr 11
Aberdeenshire                   31,356,753    11,158,328    9,690,879   Notes
Angus                           10,746,555     3,823,783    3,348,166
Argyll & Bute                   38,116,715     9,333,160    7,670,779   Assumed Backlog eliminated over 10 years

Borders                         22,439,750     6,598,363    5,700,648
Dumfries                        43,414,559    10,242,497    7,708,688   Backlog defined by cost to achieve

Highlands                       59,848,679    16,430,330 13,253,640     desired level of service expressed by PI

Moray                           13,742,761     3,618,183    2,937,423
Perth & Kinross                 20,685,037     5,822,214    4,947,710   A Class             8%

E Ayrshire                      22,451,086     5,159,962    4,005,973   B Class             8%

E Lothian                       14,168,907     3,989,688    3,321,366   C Class            12%

Fife                            32,172,789    10,308,966    9,022,372   U Class            15%

Midlothian                      10,652,349     2,963,524    2,393,732
N Ayrshire                      20,307,262     5,493,002    4,714,850   Calculation is based on current parameters, and works costs

S Ayrshire                      22,477,194     5,174,680    4,092,075   ie. Excludes cracking and edge deterioration

S Lanarkshire                   49,182,395    10,558,819    7,943,335
Stirling                        34,447,478     6,233,184    3,968,121
W Lothian                        6,557,081     3,938,886    3,702,174
Orkney                           5,612,934     2,343,799    2,083,369
Shetland                        11,808,924     3,157,819    2,543,359
Western Isles                   10,610,244     3,449,286    3,007,228
Aberdeen City                   24,710,263     6,767,564    5,631,965
Dundee                          17,971,980     4,525,221    3,553,683
Edinburgh                       66,873,911    13,650,863    9,971,325


Glasgow                          58,053,454           13,745,300 11,272,004
E Dunbartonshire                  3,028,738            1,730,663   1,395,099
Clackmannanshire                  3,704,201              937,976     790,508
E Renfrewshire                    6,912,679            1,589,320   1,251,391
Falkirk                           9,572,449            2,924,959   2,538,670
Inverclyde                        5,217,898            1,163,745     897,835
N Lanarkshire                    20,000,765            4,997,411   4,129,541
Renfrewshire                     10,633,939            2,592,263   2,087,270
W Dunbartonshire                  3,890,248            1,180,453   1,020,998
                                711,369,978          185,604,213 150,596,175