Construction of Bridge

 

The major materials used for the construction of bridge, but are not limited to the following.

• Cement
• Sand
• Aggregate
• Water
• Reinforcements
• Fly wood sheets
• Embankment Filling Materials (Type 1 or Type 2)
• Sub-base Materials
• Rock Fill
• Gunny Bags
• Concrete
• Guard rails
• Guard posts
• Kerbs
• Paving slabs

Equipment

The major equipment used for the construction of the Bridge includes, but are not limited to the following.

• JCB, and/or Backhoes, and/or Excavator
• Dump Trucks
• Tractor & Trailer
• 1.2 tone vibratory rollers
• Rammers / Plate Compactors
• Poker Vibrators
• Truck mixtures
• Sampling & Testing Equipment
• Total Station & Auto Level
• Truck Crane
• Generator
• Compressor
• Other minor tools

Safety Management and Control

Safety precaution will be taken complying with the Road Work Traffic Control Manual.

Method and Procedures

• After demolition and removing the existing bridge and repositioning the existing services as agreed with the Engineer, setting out will be carried out with the help of the survey data provided in the approved working drawings using total station. Engineer will be requested to inspect & approve the setting out.
• Excavation will be started up to required level as per drawings or directed by the Engineer while providing path to flow water of the existing stream. and the preparing the surface.
• Screed concrete will be done after preparing the bed. Form works & re bar fixing will be done for all wing wall bases.
• After getting approval for re-bar fixing & form works, base concreting will be done.
• Form works for wing wall will be done up to 150 mm level and wall concreting will be carried out.
• A rock fill layer will be laid up to required level noted on the construction drawings or directed by the Engineer at the bottom of the box base and the layer will be compacted using 1.2 tone rollers. The bed surface under the bottom of the box will be well prepared and the Engineer will be requested to inspect & approve.
• After getting approval for the bed surface, bottom screed concrete will be laid and the slope of the bed surface down to the existing stream will be maintained according to the Engineer’s instruction.
• Form-works, re-bar fixing for box bottom slab and concreting will be carried out accordingly, after having the Engineer’s approval for concreting.
• Concreting of walls will be done in two steps, the first step is form-work, re-bar fixing & concreting will be done up to half of the total height of the wall, and the remaining will be in the second step. In the second step, the finish level of the wall will be 100 mm down from the box top slab bottom level.
• Form-works, re-bar fixing & concreting will be done as per the drawing issued by the Engineer.
• After finishing the top slab, concreting of wing wall will be carried out. Form-works for wall will be done in three steps providing weep holes as directed by the Engineer or minimum of 1500 mm spacing.
• Stone lining with 50 ~ 200 graded rock will be done before starting backfilling.
• 1.13 After completing the back filling, concreting of end pilaster & fixing of hand rails will be done. Then after all miscellaneous works will be started and complete construction of the Bridge.

Quality Control

To ensure that the steps of the procedure are fully complied with the activities such as setting out, excavation, formwork, re-bar fixing, concreting, backfilling etc. certain inspections and verifications will be carried out as described in the above procedures.

Measurement Control

Cement concrete shall be measured in cubic meters of each class of concrete placed and excepted and shall confirmed to quantities given in drawings except for amendments approved by the Engineer.

The quantities of reinforcing steel and other items shown in the contract documents which are included in the completed and accepted structures shall be measured for payments as separate items involved unless otherwise specified.