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					1
                                     A PAPER
                                       ON
     CARE TO BE TAKEN FOR BETTER MAINTENANCE OF
          STEEL FOOT OVER BRIDGES AT DESIGN,
     CONSTRUCTION, INSPECTION AND MAINTENANCE
                       STAGES
                                    BY
                          V.B. SOOD DyCE/Br/Valsad
                                     &
                      A.K. AWASTHI AEN/Br/HQ/Valsad.

1.   BACK GROUND:

      Foot over bridges are important passenger amenity and passenger safety
items in station yards provided to facilitate easy movement of passengers and goods
from one platform to other or from platform to outside of Railway Station or for
crossing station yards.     Foot over bridges ensure safety by preventing the
trespassing of railway track. Proper functioning and better layout of the foot over
bridges shall be planned to ensure more and more people use foot over bridges.

      Steel foot over bridges are still popular on Indian Railways due to easy
fabrication and easy launching due to light weight & ease in modification in service
for the train information arrangement, advertising boards etc. even though PSC foot
over bridges are also being adopted. The population of foot over bridges is steadily
increasing and there are 196 foot over bridges on Western Railway as on 01-04-
2004 out of which majority are steel foot over bridges. This paper has been written
with the purpose of defining some methods to be adopted in design, construction,
inspection and maintenance stages of steel foot over bridges, so as to ensure proper
functioning of foot over bridges.

2.   INTRODUCTION:

      Maintenance of foot over bridges on Western Railway is the responsibility of
Section Engineers (Works) under open line Assistant Engineers. The maintenance of
foot over bridges is governed by para 417 of Indian Railway Works Manual & paras
117 and 104 of Indian Railway Bridge Manual.

      At present guidelines for maintenance of foot over bridges are not uniform
and proper systems are not in place for inspection and maintenance of foot over
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bridges. There are some instances where foot over bridges are not even entered in
bridge registers.

       The problems of foot over bridges maintenance have been neglected in the
past, resulting in accumulation of maintenance backlog over a period of time and the
foot over bridges in the past have been abandoned prematurely as unrepairable, or
repaired at considerable cost. Such instances are a cause of deep concern in
passenger safety as well as train safety.

3. COMMON        PROBLEMS     IN    MAINTENANCE        OF   STEEL    FOOT     OVER
BRIDGES:

      Foot over bridges handle large volumes of commuters/passengers and the
traffic peaks at the time of arrival/departure of trains. The problems in
maintenance arise due to :

         i)     Wearing course/tiles/flooring getting worn out requiring periodical
                renewal.

         ii)    Corrosion of bottom boom/flooring members of truss/ railing due to
                contact with water/debris from foot over bridges

         iii)   Corrosion in columns due to contact with water/debris from the
                platform.

         iv)    Corrosion due to non-maintenance of members in O.H.E. area.

         v)     Corrosion in the members due to being embedded in the walls of the
                rooms constructed underneath the staircase.

         vi)    Sagging of girders due to weakness in design coupled with problems
                mentioned above.
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4.   CARE TO BE TAKEN DURING DESIGN:

      During the design stage the following care shall be taken:

     i)  The design of the truss shall be done as to have simple, uncluttered layout
     of members.

     ii) The maintainability of the foot over bridge by providing easy access to all
     members for maintenance operations such as cleaning and painting shall be
     taken care of during design.

     iii) Extra care shall be taken to provide proper drainage at the flooring level
     of the foot over bridge so that the accumulation of water/ debris does not take
     place. Preferably, flooring shall be provided by keeping clear gap from the truss
     on either side to have better drainage and to avoid connection of truss with
     dust, debris and water falling on the flooring of the foot over bridge.

     iv) The design shall take care of corrosion at the most vulnerable locations
     which can not be totally eliminated by keeping some degree of redundancy in
     the design to ensure safe service life of the structure even after some
     corrosion has taken place.

     v) Staircase shall be designed with proper slope, length of flight, no of steps
     in each flight and the rise and tread of each step in accordance with the
     provisions of National Building Code for the convenience of the passengers. This
     is the single most important factor that promotes or inhibits the use of the
     foot over bridges by the passengers.

     vi) Wind load shall be taken considering the possibility of the entire height of
     the foot over bridge being covered in advertisement boards during use.

5.   CARE TO BE TAKEN DURING CONSTRUCTION:

     Care taken during construction is most important and it avoids many problems
     arising in maintenance.

     i)   The foot over bridges footings having holding down bolts are vulnerable to
     corrosion and this results in shearing off of the holding down bolts. Wherever
     holding down bolts are to be used, galvanized bolts shall be provided. The new
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    drawings of footings having embedded column is performance wise better in
    field and shall be used.

    ii) For gravity type foundations, the life of embedded column shall be ensured
    by :
          a) The welds and connection bolts shall be designed of adequate size to
       take care of corrosion in service.

        b) The footing shall be embedded in good quality properly compacted
     concrete.

        c) The steel embedded in concrete shall be protected against corrosion by
     providing one thick coat of bituminous paint.

    iii) The bottom boom/flooring of the foot over bridges and stairs is vulnerable
    to corrosion due to contact between different material, accumulation of
    water/debris. Such vulnerable members shall be metallised/epoxy painted
    outside track after complete erection, or in situ after launching.

    iv) Columns of foot over bridges shall be embedded in good quality concrete
    for a height of 1 m above floor of platform/general ground level to prevent
    contact with water/debris from platform surface.

    v) Wearing coat shall be provided in flooring with different colour pigments
    in concrete to give indication of the extent of wear, so that main slab does not
    wear off and safety is ensured by timely renewal of wearing coat.

    vi) Proper drainage shall be ensured to prevent any accumulation of water,
    especially near panel points.

    vii) The steel columns and bracing in rooms constructed under staircase shall
    not be encased in walls. However, if the same is unavoidable, the members shall
    be protected against corrosion by applying a coat of bituminous paint.

    viii) Properly anchored steel angles shall be provided at nosing of steps to
    prevent damage to the flooring on steps. This helps in preventing falling of the
    passengers by tripping over loose nosing angles or over damaged flooring of the
    steps.
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6.     CARE TO BE TAKEN DURING INSPECTIONS AND MAINTENANCE:

        The foot over bridges are to be inspected once a year before monsoons by
     Section Engineer (Works) and once a year after monsoons by the Assistant
     Engineer (Open Line) as per para 117 and 102 of Indian Railway Bridge Manual
     with detailed inspection being done once in five years.

        The record of inspections shall be kept in a properly bound register having
     chronological records of inspections of successive years. The drawings of foot
     over bridges and design details form an important part of maintenance regime for
     foot over bridges and shall be available with the maintenance engineers.
     Maintenance practice shall aim at preventing premature failure of individual
     components.

        During inspections, the following items shall be carefully inspected and the
     remedial action shall be taken for maintenance to ensure proper service life of
     the foot over bridge:

     Item         Defects to be observed Action to be taken for maintenance
                  during inspections
     Foundation   i.    Spalling/cracking      of i.     Epoxy repairs in the cracks/
                  concrete in foundations         spalled concrete OR increasing
                                                  section area of concrete in foundation
                  ii.   Loose     or    corroded ii.     Regrouting of holding down
                  holding down bolts              bolts and/or replacement of holding
                                                  down bolts
                  iii.  Looseness of nuts of iii.        Provision of missing nuts and
                  holding down bolts.             providing packing in loose nuts.
                  iv.   Accumulation of water iv.        Improving       drainage   and
                  and lack of cleanliness near cleanliness near holding down bolts
                  bed plates/ holding down bolts and/ or encasing the bed plates      in
                                                  good quality concrete upto 1m height
                                                  from the ground.
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    Item        Defects to be observed Action to be taken for maintenance
                during inspections
    Columns     i.Verticality of columns.          i.      Strengthening of columns by
                                                   providing stays and extra footing
                                                   area.
                ii.      Cracks in welding.        ii.     Repairs by welding and splicing.
                iii.     Bends or damage in iii.           Repairs     by    welding     or
                secondary members such as replacement                of    the   members
                bracing, gussets etc.              affected.
                iv.      Condition of painting and iv.     Repainting as required and
                extent of corrosion, especially splicing at the places where corrosion
                near the junction of the truss already occurred after proper design.
                and column
    Support    i.        Missing/ loose bolts in i.        Provide missing bolts, tighten
    points of connection.                          bolts, if required.
    trusses on ii.       Deformation/ corrosion ii.        Check from design point of
    columns     of cleat angle supporting truss view, reasons for such deformation.
                over the columns.                  Replacing corroded cleat angles.
               iii.      Jammed          rotation/ iii.    Cleaning and oiling of the
                movement of bearings.              bearings to ensure free movement/
                                                   rotation of bearings. Dust covers to
                                                   be provided where required.
    Steel      i.        Corrosion of structural i.        Repainting, if required, and
    Truss      members                             repairs and splicing of corroded
                                                   members after proper design.
               ii.       Distortion     of     the ii.     Complete design check of the
               members due to overstressing girder and strengthening of trusses.
               of members.
               iii.      Cracks in the members.    iii.    Splicing of the members after
                                                   design check.
               iv.       Condition of painting     iv.     Repainting with
                     a. General corrosion               a. Normal painting.
                     b. Corrosion in OHE area.          b. Epoxy painting/ Metallising of
                                                        members in OHE area.
               v.        Condition of the cross- v.        Welding of cracks and providing
               girder - bracing connection.        additional members in connections
                                                   where only bolts are used for the
                                                   connections to prevent the cross
                                                   girders from falling of if the bolt
                                                   loosens/falls off.
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    Item       Defects to be observed Action to be taken for maintenance
               during inspections
               vi.     Pinned Connections and vi.        Replacement of broken pins/
               cotters.                           cotters and proper splitting of the
                                                  ends of cotter pins.
               vii.    General    condition   of vii.    Design check for any sagging of
               truss                              the truss or excessive vibrations
                                                  under load/ train passing.
    PSC        i. Cracks in members               i.     Epoxy grouting of cracks.
    Girders                                       Design review.
               ii. Crack at junction of I- ii.           Strengthening of connection of
               girders and deck slab.             I-girders and deck slab and design
                                                  review.
               iii.    Spalling of concrete.      iii.   Complete stripping of spalled
                                                  concrete and providing concrete cover
                                                  afresh.
               iv.     Honey      combing      in iv.    Epoxy grouting and corrosion
               concrete.                          protection by epoxy painting on
                                                  surface.
               v. General corrosion               v.     Epoxy painting on surface.
               vi.     Loss of camber in PSC I vi.       Design review and retrofitting
               girders                            of girders.
    Stairs     vii.    Spalling of concrete vii.         Repairs of the slab by guniting/
               from bottom side of stairs.        epoxy mortar.
               viii. Nosing        angle     and viii. Repair of loose/hanging nosing
               flooring.                          angles and worn out flooring.
    Flooring   i.Excess wear in wearing coat/ i.         Renewal of wearing coat and
               tiles.                             tiles.
    General    i.      OHE             induction i.      Repairs by welding/ splicing in
               protection      sheet, covering the connections. Renewal, if required.
               sheeting, covering sheet truss,
               hand railing etc.
               ii.     Pockets having drainage ii.       Improving drainage through
               problems.                          renewal of the wearing coat and/ or
                                                  surface coating.
               iii.    Damage due to wear in iii.        Replacement of floor slab and/
               floor slab.                        or re-plastering the spalled concrete.
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7. RECOMMENDATIONS FOR IMPROVEMENTS IN EXISTING SYSTEM OF
RECORDING INSPECTIONS AND ROUTINE MAINTENENACE:

     The following improvements are required in the present system of recording
     inspections and routine maintenance:

     i.        Detailed inspection of structures once in five years as per
     provisions of Indian Railway Bridge Manual are not being done in field at
     present, the same shall be done.

     ii.   Bottom boom of foot over bridges to be inspected after opening out
     the flooring once in every 10 years.

     iii.  Metallizing after sand blasting shall be done in the bottom boom of the
     foot over bridges and OHE areas which are subjected to sever corrosion and
     which cannot be readily repainted.

     iv.   The space under the foot over bridges shall not be permitted as far as
     possible to be converted into rooms since this prevents the proper inspections
     of the foot over bridges and also creates problems in maintenance.

     v.    Advertising boards/ information boards/ sheeting shall be provided on
     the foot over bridges after consultation with the Section Engineer (Works) in
     charge and the same shall be so provided that the design assumptions of the
     foot over bridge for wind loading are not violated.

8.    CONCLUSION:

        Foot over bridges are very important passenger amenity items, especially at
     busy railway stations. Proper care taken at various stages of design, construction
     and maintenance of a foot over bridges will go a long way in ensuring proper
     service and life of foot over bridges and ensuring safety of foot over bridges.
     This will also help the railway in serving the passengers better, ensuring
     passenger convenience and safety in the process.

9.    BIBLIOGRAPHY:

           i)    Indian Railway Bridge Manual, 1998.
           ii)   Indian Railway Works Manual, 2000.

				
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