06-STEEL WORK/BRIDGES



STEEL WORK FOR BRIDGES

MATERIAL

  1. Steel of Quality 'A' Grade Designation E250 (Fe410W) as rolled semi-killed or killed conforming to IS: 2062 shall be used for foot-over bridges and other structures subjected to non-critical loading.
  2. Quality 'B' Grade Designation E250 (Fe410W) fully killed and normalized/ controlled cooled, conforming to IS: 2062 shall be used for welded/riveted girders subjected to dynamic loading.
  3. Rolled sections like angles, channels, I-sections etc., conforming to IS: 2062 Quality 'A' shall be used in structures till such time rolled sections conforming to IS: 2062 Quality 'B' are not available in the market.
  4. High tensile steel shall comply in all respects with the requirement of IS: 2062 Grade Designation E410 (Fe540) or E450 (Fe570) Quality 'D' (both copper bearing quality) according to the welded or riveted work respectively.
  5. Steel for bolts shall conform to property class 4.6 or 6.6 as specified in IS: 1367 accordingly, as the structural steel specification is for mild steel or high tensile steel.
  6. Steel for drifts shall be in accordance with IS: 1875 for forged quality steel or IS: 7283 for hot rolled bars.
  7. Steel for rivets shall comply with the requirement of IS: 1148 for hot rolled rivet bars for general structural purposes and IS: 1149 for high tensile steel rivet bars for high strength structural purposes.
  8. Steel casting shall comply with IS: 1030 for normal temperature zone and to IS: 4899 for use at low temperature zone.
  9. The physical and chemical requirements of material shall be verified.

 Straightening, bending and pressing

  1. Straightening and flattening of steel shall be done by methods that will not injure the metal. Hammering shall not be permitted.
  2. For straightening by heating, the temperature of steel shall not be more than 6500C.
  3. Heating and cooling rate shall be appropriate to the particular type of steel and shall be agreed by the Engineer. Accelerated cooling shall not be used without the approval of the Engineer.
  4. Steel having yield stress more than 360 MPa shall not be heat curved.
  5. Rolled beams and girders may be curved by either continuous or V-type heating as approved by the Engineer.
  6. For flange thickness of 32 mm or more, both inside and outside surfaces shall be heated concurrently.
  7. The heat of bending shall be conducted so that the temperature of steel does not exceed 6200C. The girder shall not be artificially cooled until temperature comes down to 3150C by natural cooling. The method of artificial cooling has to be taken Care and approved by the Engineer.

Preparation of edges, ends and surfaces

  1. Material shall be cleaned and any burring, scales or abnormal irregularities shall be removed.
  2. End/edge planing and cutting shall be done by any one of the following prescribed methods or left as rolled.
  1. Shearing, cropping, sawing, machining or machine flame cutting.
  2. Hand flame cutting with subsequent grinding to a smooth edge.
  3. Shearing edges of plate not more than 16 mm thick with subsequent grinding to smooth profile, which are for secondary use such as stiffeners and gussets.
  1. Where machining for edge preparation in butt joint is specified, the ends shall be machined after the members have been fabricated.
  2. Outside edges of plate and section, which are prone to corrosion, shall be smoothened by grinding and filing.

Rivet and bolt holes

  1. All holes for rivets or bolts shall be either punched or drilled. The diameter of holes shall be 1.5 mm and 2.0 mm larger for bolts/rivets less than 25 mm dia. and greater than or equal to 25 mm respectively, if not specified in the Drawing.
  2. The tolerance for diameter of the holes shall be equal to +0.15 mm to 0.0 mm.
  3. For high strength friction grip bolts, the diameters of holes shall be 1.5 mm larger than those of bolts when the number of plies in the grip does not exceed three, while it is 1.5 mm to 3.0 mm when plies in grip is more than three, unless otherwise specified in the Drawing.

Bolted construction

  1. All joint surfaces for bolted connection including bolts, nuts, washers shall be free of scale, dirt, burrs or other foreign material and defects that would prevent solid seating of parts.
  2. The slope of surface of bolted parts in contact with bolt head and nuts shall not exceed 1:20 plane normal to bolt axis. Otherwise suitable tapered washers shall be used.
  3. All fasteners shall have a washer under nut or bolt head, whichever is turned in tightening.
  4. Each fastener of joint shall be tightened to specified value or equal to 70% of specified minimum tensile strength by hand wrenches (turn of nut method) or calibrated wrenches or manual torque wrenches, impact wrenches or any other method as specified by the Engineer.
  5. Bolted connections of structural joints using high tensile friction grip bolts shall comply with requirements mentioned in IS: 4000.

Riveted construction

  1. Assembled riveted joint surface including those adjacent to the rivet head shall be free of scale, dirt, burrs or foreign material and defects that would prevent solid seating of parts.
  2. The part/members to be riveted shall be firmly drawn together with bolts, clamps or track weld. Every third hole of the joint shall have assembly bolts till riveted. Drift shall be used only for matching of holes of the parts/members, but not to the extent as to distort the holes. Drift of larger size than the normal diameter of the holes shall not be used.
  3. Rivets shall be heated uniformly to a 'light cherry red colour' from 6500C to 7000C for hydraulic riveting and 'Orange colour' for pneumatic riveting of mild steel rivets. High tensile steel rivets shall be heated up to 11000C. Any rivet which is heated more than the prescribed limit shall not be driven.
  4. Rivet shall be driven in hole when hot so as to fill the hole as completely as possible and shall be of sufficient length to form a head of the standard dimension. When countersunk head is required the head shall fill the countersunk hole. Projection after countersinking shall be ground off wherever necessary.
  5. The riveting shall be done by hydraulic or pneumatic machine unless otherwise specified by the Engineer.
  6. Any defective rivet due to defect in head size or head driven off the centre shall be removed and replaced.
  7. The parts not completely riveted in the shop shall be secured by bolts to prevent damage during transport and handling.

Welded construction

  1. Surfaces of edges to be welded shall be smooth, uniform and free from fins, tears, cracks and other discontinuities. Surface shall also be free from loose or thick scale, slag rust, moisture, oil and other foreign materials.
  2. The general welding procedures including particulars of the preparation of fusion faces for metal arc welding shall be carried out in accordance with IS:9595.
  3. The welding procedures for shop and site welds including edge preparation of fusion faces shall be submitted in writing in accordance with IS: 9595 for the approval of the Engineer before commencing fabrication.
  4. Electrodes to be used for metal arc welding shall comply with relevant BIS specifications.
  5. Procedure test shall be carried out as per IS: 3613 to find out suitable wire-flux combination for welded joint.
  6. Assembly part for welding shall be in accordance with IS: 9595.
  7. The welded temporary attachment shall be avoided as far as possible and if unavoidable, the same shall be approved by the Engineer and any scars due to this shall be removed by cutting or chipping and the surface shall be finished smooth by grinding to the satisfaction of the Engineer.
  8. For welding any particular type of joint, welders shall qualify to the satisfaction of the Engineer in accordance with appropriate welders qualification test as prescribed in the relevant BIS standards.
  9. In assembling and joining parts of a structure or of built-up members, the procedure and sequence of welding shall be such as to avoid distortion and minimise shrinkage stress.
  10. All requirements regarding preheating of present material and inter pass temperature shall be in accordance with IS: 9595.
  11. Peening of welding shall be carried out wherever specified by the Engineer.
  12. Where it is specified that the butt welds are to be ground flush, the loss of parent metal shall be not greater than that allowed for minor surface defects.
  13. The joints and welds listed below are prohibited as these do not perform well under cyclic loading:

i) Butt joints not fully welded throughout their cross section.

ii) Butt welds made from one side only without any backing strip.

iii) Intermittent butt welds.

iv) Bevel and J-preparations in butt joints for other than horizontal position.

v) Plug and slot welds.

Welding of stud shear connectors

  1. The stud shear connectors shall be welded in accordance with the manufacturer's instructions including preheating.
  2. The stud and surface to which studs are welded shall be free from scale, moisture, rust and other foreign material. The stud base shall not be painted, galvanised or cadmium plated prior to welding.
  3. Welding shall not be carried out when temperature is below 0?C or surface is wet.
  4. The welds shall be visually free from cracks and lack of fusion and shall be capable of developing at least the nominal ultimate strength of studs.
  5. The procedural trial for welding the stud shall be carried out when specified by the Engineer.

Shop assembly

  1. The steel work shall be temporarily assembled at the place of fabrication.
  2. Assembly shall be full truss or girder, unless progressive truss or girder assembly, full chord assembly or progressive chord assembly as specified by the Engineer.
  3. The field connections of main members of truss, arches, continuous beam spans, bents, plate girders and rigid frame assembled, aligned, accuracy of holes, camber shall be checked by the Engineer and then only reaming of subsize holes to specified size shall be taken up.
  4. The assembly will be dismantled after final drilling of holes and approval of the Engineer.
  5. The camber diagram showing camber at each panel point, and method of shop assembly and any other relevant detail shall be submitted to the Engineer for approval.

Painting

Typical guidelines for epoxy based paints and the conventional painting system for bridge girders are specified under Section1900 of MoRTH Specifications.

FABRICATION TOLERANCES

  1. The fabrication tolerance for various superstructure elements shall be as per IRS Specification for fabrication and erection of steel girder bridges and locomotive turn-tables as shown in the tables 3500-1, 3500-2, 3500-3 and 3500-4.

               Table: Manufacturing tolerances for plates girders

Sl.

No.

Dimensions specified

Toler-

ances

(mm)

Notation in

Fig.3500-1

1

Overall length of the girder

+6/-3

a

2

Distance between centers of bearings

+1/-1

b

3

Depth over angles

+3/-1

c

4

Corner of flange angle to edge of web at any place

+0/-2

d

5

Diagonal at either end of the assembled span

+3/-3

e

6

Centers of intersection of diagonals with

girder flange measured along the girder flange

+3/-3

f

7

Butting of compression ends:

 

 

 

(i) Throughout

+0/-0.15

            g

 

(ii) Locally

+0/-0.25

            g

8

Butting edge at web splices

+0/-1

            h

9

Straightness of girder bottom laid on the

ground and checked with piano wire:

 

 

 

(i) Vertical plane:

 

 

 

Convexity

+0/-3

             j

 

Concavity

+0/-0

             j

 

(ii) Horizontal plane

+2/-2

             j

 

      Table: Manufacturing tolerance for open web girders

Sl.

No.

Dimensions specified

Tolerances

(mm)

Notation in

Fig

1

Over-all length of girders

+1/-1

k

2

Distance between centre to  centre of bearing

+1/-1

l

3

Cross diagonals of assembled bays

+1/-1

m

4

Centre to centre of cross girders

+1/-1

n

5

Centre to centre of rail bearer

+1/-1

p

6

Panel length in lateral bracing system

+1/-1

q

7

Distance between inter section line of chords: vertical and horizontal

+1/-1

r

8

Butting edges of compression members:

 

 

 

(i) Throughout

+0/-0.15

s

 

(ii) Locally

+0/-0.15

s

9

Twist in members

+0/-0

t

10

Lateral distortion between points  of lateral supports

+0.001 L/

-0.001L

u

Sl.

No.

Dimensions specified

Toler-

ances

(mm)

Notation in

Fig

1

Between any two holes in group

+0.5/-0.5

v

2

Between holes of one group and another

+1/-1

w

3

Edge distance

+0.5/-0.5

x

4

Distance of 'GO' gauge open holes in 

two or thicknesses

+0/-0.8

y

 

                                        

Sl.

No.

Dimension specified

Tolerances (mm)

1

Depth at the centre of web

+2/-1

 

2

Flange out of square for  compression member and beams

1/200 or 3 max from edge

(whichever is less)

3

Displacement of vertical axis of  the web with reference to flange. 

2

4

Box width of member

-0/+3

5

Verticality of stiffener or          diaphragm  out of plumb.

2

6

Overall length of girder

+6/-3

7

Depth of the girder at the ends

+3/-1

8

Depth of the girder at the    centre of span

+2/-1

9

Distance between centre of bearings

+1/-1

10

Diagonal at either end of  assembled span

+3/-3

  1. Bolted splice shall be provided with steel packing plates where necessary to ensure that the sum of any unintended steps between adjacent surfaces does not exceed 1 mm for HSFG bolted joints and 2 mm for other joints.
  2. All parts in an assembly shall fit together accurately within tolerances specified in IRC: 24 as shown in table 3500-5, unless otherwise specified in the Drawing.
  3. A machined bearing surface as specified in the Drawing, shall be machined within a deviation of 0.25 mm for surfaces that can be inscribed within a square of side 0.5 m.
  4. In welded butt joints, misalignment of parts shall not exceed the lesser of 0.15 times the thickness of thinner pats or 3 mm. However, if due either to different thickness arising from rolling tolerances or combination of rolling tolerances with above permitted misalignment, the deviation is more than 3 mm, it shall be smoothened by slopes not steeper than 1:4.

 Table: Manufacturing tolerance for individual components

Sl.

No.

Dimensions specified

Tolerances

(mm)

1

Length:

 

 

a) Member with both ends finished for contact bearing

±1

 

b) Individual component of members with end plate connection.

+0/-2

 

c) Other Members:

 

 

i) Upto and including 12 m

±2

 

ii) Over 12 m

± 3.5

2

Width:

 

 

a) Width of built-up girders.

±3

 

b) Deviation in the width of members required to be

inserted in other members.

+0/-3

3

Depth:

 

 

Deviation in the depths of solid web and open web.

+3/-2

4

Straightness:

 

 

a) Deviation from straightness of columns.

L/300

(15 Max)

 

i)    In elevation

+5

 

ii) In plan

+0

5

Deviation of centre line of web from centre line of flanges in built-up members at contact surfaces.

+3

6

Deviation    from flatness    of plate webs of built-up

members in a length equal to the depth of the member

0.005d

(2 Max)

7

Tilt of flange of plate girders.

 

 

a) At splices & stiffeners, at supports, at the top flanges of plate girders,

 at bearings.

0.005b

(2 Max)

 

b) At other places.

0.015b

(4 Max)

8

Deviation from squareness of flange to web of columns and box girders.

L/1000

9

Deviation from squareness of fixed base plate (not machined) to axis 

of column. The dimension shall be measured parallel to the longitudinal 

axis of the column at points where the outer surfaces of column section

make contact with the base plate.

 

D/500

10

Deviation from squareness to machined ends to axis of columns.

D/1000

11

Deviation from squareness of machined ends to axis of beams or girders.

D/1000

12

Ends of members abutting at joints through cleats or end plates, 

permissible deviation from squareness of ends.

1/600 of

depth

(1.5 Max)

 Rolling and cutting tolerance shall be as per IS: 1852. The thickness tolerance check measurements of plates and rolled sections shall be taken at not less than 15 mm from edge.

INSPECTION

  1. No protective treatment shall be applied to the work until the appropriate inspection and testing has been carried out.
  2. The stage inspection shall be carried out for all operations so as to ensure the correctness of fabrication and good quality.
  3. All the steel sections used in the fabrication shall have mill test certificate clearly indicating the specification to which the steel conforms and whether steel is killed and normalized. All the cast mark numbers/heat mark numbers shall be recorded along with the number of plates in a register as soon as the plates are received. Whenever the steel is received without any test certificate, a sample test piece from plate of each cast mark number is to be cut and sent for testing. If required, rivets, bolts, nuts, washers, welding consumables, steel forging, casting and stainless steel shall be tested for mechanical and chemical properties as per various Indian standards as may be applicable and shall conform to requirements specified in IS: 2062 and IS: 11587.
  4. Lamination check in plates shall be carried out by ultrasonic testing or any other approved methods or should have the mill test certificate for the testing. Flame cut edges without visual signs of laminations need not be tested unless insisted by the Engineer.
  5. Steelwork shall be inspected for surface defects and exposed edge lamination during fabrication and blast cleaning. Significant edge laminations found shall be reported to Engineer for his decision.
  6. Chipping, grinding, machining or ultrasound testing shall be used to determine depth of      imperfection.
  7. For dynamically loaded structures recommended criteria for   allowable discontinuities for edge defects and repair procedure shall be as given in table 3500-6, until and unless specified otherwise. The weld procedure shall be appropriate to the material.
  8. Horizontal curvature and vertical camber shall not be measured for final acceptance before all welding and heating operations are completed and flanges have cooled to uniform temperature.
  9. Horizontal curvature shall be checked with girder in the vertical position by measuring offsets from a string line or wire attached to both flanges or by any other suitable means. Camber shall be checked by adequate means.
  10. Acceptable deviation in holes drilled and reamed for mild steel and high strength friction grip bolts should be as per appropriate BIS.
  11. Bolted connection joints, black bolts and high strength bolts shall be inspected and tested for compliance or requirements mentioned in IRC: 24.
  12. The Engineer shall observe the installation and tightness of bolts so that correct tightening procedure is used and shall determine that all bolts are tightened.
  13. Regardless of tightening method used, tightening of bolts in a joint should commence at the most rigidly fixed or stiffest point and progress towards the free edges, both in initial snug tightening and in final tightening.
  14. The tightness of bolts in connection shall be checked by inspection wrench, which can be torque wrench, power wrench or calibrated wrench.
  15. Tightness of 10% bolts, but not less than two bolts, selected at random in each connection shall be checked by applying inspection torque.

  Table: Discontinuity of edge

Sl.

No.

Discontinuity

Repairs required

1

Discontinuities of maximum 3 mm in depth,

any length for material thickness up to 200 mm

None.

 

2

Discontinuities of 3 mm to 6 mm in depth and

over 25 mm in length for thickness up to 100

mm and 6 mm to 12 mm depth, over 50 mm in

length for thickness 100 mm to 200 mm

 

Remove and need not

be welded.

 

3

Discontinuities of 6 mm to 25 mm in depth over

25 mm in length for thickness upto 100 mm

and 12 mm to 25 mm in depth, over 25 mm in

length for thickness over 100 mm to 200 mm

Remove and weld. No

single repair shall

exceed 20% of edge

being repaired.

 

4

 

Discontinuities over 25 mm in depth, any

length for thickness 100 mm to 200 mm

With approval of

Engineer remove to

depth of 25 mm and

repair by weld block.

5

On edges cut in fabrication, discontinuities of

12 mm maximum depth, any length.

None.

  1. If no nut or bolt head is turned by this application, connection can be accepted as properly tightened, but if any nut or head has turned all bolts shall be checked and if necessary retightened.
  2. Bolts and bolted connection joints with high strength friction grip bolts shall be inspected and tested according to IS: 4000.
  3. Rivets and riveted connection shall be inspected and tested for compliance or requirements mentioned in IRC: 24.
  4. The firmness of the joint shall be checked by 0.2 mm filler gauge, which shall not go inside under the rivet head by more than 3 mm. There shall not be any gap between members to be riveted.
  5. Driven rivets shall be checked with rivet testing hammer. When struck sharply on head with rivet testing hammer, rivet shall be free from movement and vibration.
  6. All loose rivets and rivets with cracked or badly formed defective heads or with heads which are unduly eccentric with shanks, shall be cut out and replaced.
  1. The alignment of plates at all bolted splice joints and welded butt joints shall be checked for compliance with requirements of IRC: 24.
  1. Testing of flame cut and sheared edges are to be done where the hardness criteria of IRC: 24 are adopted. Hardness testing shall be carried out on six specimens.
  1. Welder qualification test shall be carried out as per requirements laid down in relevant IS standards for the respective approved welding procedure to the satisfaction of the Engineer.
  1. Welding procedures, welded connection and testing shall be in compliance of requirements mentioned in IRC: 24.
  2. All metal arc welding shall be in compliance with the provision of IS: 9595. The method of inspection shall be according to IS: 822 and extent of inspection and testing shall be in accordance with the relevant standards or in the absence of such a standard, as agreed with the Engineer.

TESTING

The destructive and non-destructive test of weld shall be carried out according to IS:7307 (Part-1).

1. Non-destructive testing of welds

One or more of following methods may be applied for inspection or testing of weld.

1.1 Visual inspection

  1. All welds shall be visually inspected, which should cover all defects of weld such as size, porosity, crack in the weld or in the HAZ (Heat affected zone) etc. Suitable magnifying glass may be used for visual inspection.
  2. A weld shall be acceptable by visual inspection if it shows that:
  1. The weld has no crack.
  2. Thorough fusion exists between weld and base metal, and between adjacent layers of weld metal.
  3. Weld profiles are in accordance with requisite clauses of IS: 9595 as agreed with Engineer.
  4. The weld shall be of full cross section, except for the ends of intermittent fillet welds outside of their effective length.
  5. When weld in transverse to primary stress, undercut shall not be more than 0.25 mm deep in the part that is under cut and shall not be more than 0.8 mm deep when the weld is parallel to the primary stress in the part that is undercut.
  6. The fillet weld in any single continuous weld shall be permitted to under run the nominal fillet weld size specified by 1.6 mm without correction provided that undersize portion of the weld does not exceed 10% of the length of the weld. On the web to flange welds on girders, no under run is permitted at the ends for a length equal to twice the width of the flange.
  7. The piping porosity in fillet welds shall not exceed 1 in each 100 mm of weld length and the maximum diameter shall not exceed 2.4 mm, except for fillet welds connecting stiffeners to web where the sum of diameters of piping porosity shall not exceed 9.5 mm in any 25 mm length of weld and shall not exceed 19 mm in any 300 mm length of weld.
  8. The full penetration grove weld in butt joints transverse to the direction of computed tensile stress shall have no piping porosity. For all other groove welds, the maximum diameter shall not exceed 2.4 mm.

1.2 Magnetic particle and radiographic inspection

  1. Welds that are subject to radiographic or magnetic particle testing in addition to visual inspection shall have no crack.
  2. Magnetic particle test shall be carried out for detection of crack and other discontinuity in the weld according to IS: 5334.
  3. Radiographic test shall be carried out for detection of internal flaws in the weld such as crack, piping porosity, inclusion, lack of fusion, incomplete penetration etc. This test may be carried out as per IS: 1182 and IS: 4853.

1.3 Ultrasonic inspection

  1. The ultrasonic testing in addition to visual inspection shall be carried out for detection of internal flaws in the weld such as cracks, piping porosity inclusion, lack of fusion, incomplete penetration etc.
  2. Acceptance criteria shall be as per IS: 4260 or any other relevant BIS Specifications and as agreed by Engineer.

1.4 Liquid penetrant inspection

The liquid penetrant test shall be carried out for detection of surface defect in the weld as per IS: 3658, in addition to visual inspection.

1.5 Stud shear connectors

  1. Stud shear connectors shall be subject to the following tests:
  1. The fixing of studs after being welded in position shall be tested by striking the side of the head of the stud with 2 kg hammer, to the satisfaction of the Engineer.
  2. The selected stud head stroked with 6 kg hammer shall be capable of lateral displacement of approximately 0.25 height of the stud from its original position. The stud weld shall not show any signs of cracks or lack of fusion.
  1. The studs whose welds have failed the test given in (i) and (ii) shall be replaced.

Inspection of members and components

1. Inspection requirement

  1. The fabricated member/component made out of rolled and built-up section shall be checked for compliance of tolerances given in table 3500-1.
  2. Inspection of members/components for compliance with tolerances, the check for deviation shall be made over the full length.
  3. During checking the inspection requirement shall be placed in such a manner that local surface irregularities do not influence the results.
  4. For plate, out of plane deviation shall be checked at right angle to the surface over the full area of plate.
  5. The relative cross girder or cross frame deviation shall be checked over the middle third of length of cross girder or frame between each pair of webs and for cantilever at the end of member.
  6. During inspection, the component/member shall not have any load or external restraint.

2. Inspection stages

The inspection to be carried out for compliance to tolerances shall include but not be limited to the following stages:

  1. For completed parts, component/members on completion of fabrication and before any subsequent operation such as surface preparation, painting transportation, erection.
  2. For webs of plate and box girders, longitudinal compression flange stiffeners in box girder and orthotropic decks and all web stiffeners at site joints, after completion of site joint.
  3. For cross girders and frames, cantilevers in orthotropic decks and other parts in which deviations have apparently increased, on completion of site assembly.

3. Acceptance criteria

  1. Where, on checking member/component for the deviations in respect of out-of-plane or out-of straightness at right angles to the plate surface, and any other instances, exceed tolerance, the maximum deviation shall be measured and recorded.
  2. The recorded measurements shall be submitted to the Engineer, who will determine whether the component/ member may be accepted without rectification, with rectification or rejected.

RELATED CODES:

Steel construction work=IS Codes :456:2000, 800:2007, 801:1975

1.IRC: 24-Standard specification and code of practice for road bridges: Steel road bridges.1

2.IRC: SP-104-Guidelines for fabrication and erection of steel bridges.

3.Indian Railway Standard:"Specification for fabrication and erection for steel girder bridges and locomotive turn tables".

4.Indian Railway Standard:"Guidelines on fabrication of steel structure of foot over bridges".

5.Indian Railway Standard: "Code of practice for metal arc welding in structural steel bridges carrying rail, rail-cum-road or pedestrian traffic."

6.MoRTH-Specification for Road and Bridge works (5th revision).

*****