Constructions Highlights

  • Construction Technique adopted For Foundation: Underwater Well Sinking for maximum depth of 50 meter within Steel Caissons.
  • Floating caissons were used for water wells.
  • The existence of an old submerged wooden log at 25 meter depth created construction problem in P4 well sinking. The log was removed by under- water excavation by engaging Divers and took 4 months to reach final sinking level of P4 Well.
  • Pre Cast Segments Launched in place using Floating Barges.
  • This single project was having involvement of various types of civil construction like Well Foundation, Pile Foundation, Retaining wall, Segment Casting and Erection, Road Over Bridge, Road Under Bridge, Tunnel, Roads, Buildings, Culverts, Under Pass etc.
  • The main bridge was of precast segmental concrete structures with transverse bonded Pre-stressing tendons.
  • Main bridge spans were erected by Balanced Cantilever method with Epoxy joints, permanent PT bars and internal tendons. Single plane of stay cables were adjusted after applying crash barrier and wearing coat.
  • The Geometry control of the Main Bridge during erection was made with the help of MC3D software. This software was used to maintain an accuracy of +/- 0.3mm for monitoring the deflection as well as the placement of the starter segment next to the pier table.
  • Stringent Geometric Control at the Pre- cast yard by way of double survey checking ensured control on casting of segments nearer to the theoretical values. This helped smooth erection of segments.
  • The Cycle Time for Main Bridge Segment Casting and Erection was reduced to the tune of 2.5 days and 1.92 days respectively which were very close to the planned cycle time.
  • The construction of RUBs by Box pushing method was done without blocking the existing Main Railway Line running above.
  • Such type of Multifaceted Project took only 39 months for completion.

  • Major Challenges faced & resolved during construction:
  • Howrah side CCR line Rail under Bridge :Box pushing with only 895mm soil cushion in between box top & Raiway track called for a great cautionThe details of the soil properties of the railway embankment was studied, by conducting bore holes and final construction method was adopted.
  • Bally ROB girder launching on busy six nos Howrah -Delhi main line track was a challenge. The entire railway traffic schedule was studied with railway authorities and it was confirmed that the traffic block can only be given in the midnight for maximum two hours. Finally the detailed scheme of launching was worked out to execute the work within the specified block period without any extension of working period.
  • Bore tide effect in the river - The tidal data has been studied for last three years and one year long hourly monitoring has been done to study the nature and likelihood of the bore tides and its effect on the various locations. Based on the data obtained.detailed anchoring scheme has been finalized.
  • Tilt and shift of the well - Well wise soil properties were studied and expert advice taken regarding the possibilities of well tilt and shift for every individual case. Selfweight sinking along with air and water jetting techniques were adopted along with the kentledge application to counter tilt and shift.
  • Transportation of main bridge segment - The main bridge super structure segment of size 29 meter X 3.5 meterwere required to be transported to river from the Pre Cast yard location. It was decided to avoid the segment transportation using road and so, the Pre Casting yard was established on the river bank with Gantry way projecting into the river. This resulted in smooth flow of segment transport to their destinations at mid river.
  • Match Cast Joints - 3D Casting Curve was developed for geometric control. In each joint the survey coordinates were calculated on the basis of Casting Curve and these general coordinates along with camber produced the set up coordinates before casting All human errors cumulated which were adjusted in a number of segments with the help of the MC 3D software keeping the Match Cast twist within tolerance.


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