Design and Construction (502.02)
Documentation Requirements – 502 Structures for Maintaining Traffic
This item consists of the construction, maintenance, and subsequent removal of a temporary bridge or culvert for maintaining traffic.
The waterway opening generally should be not less than 75 percent of the effective waterway of the proposed structure based on the 5-year water level. The deck of a bridge must have at least a 23-foot (7.0 m ) clear roadway and, if pedestrian facilities existed, at least a 4-foot (1.2 m) wide sidewalk must be provided.
The proposed plan should be reviewed in the District for accuracy of existing features not shown on the project plans. If the proposed waterway is less than 75 percent, comments regarding local knowledge of stream fluctuations will be helpful. In lieu of a bridge, a pipe culvert or multiple pipe culverts with required waterway may meet the requirements for a bridge and will be considered when submitted.
Submit construction plans in accordance with 501.05
All stress-carrying materials to be used in any temporary structure must be carefully examined, since used materials generally are employed and may not possess the physical properties considered in the design. Timber elements must be examined for specified size and soundness. Steel members must be examined for holes and alterations that would reduce their section modules. Welded splices in members are not cause for rejection providing the welds have been made properly and are proven to be free from defects. Existing welded butt splices must be subject to radiographic inspection. Approved welders using approved welding consumables should perform welding. Hardware and miscellaneous materials must be as specified on the submitted plan.
Piles must be driven in accordance with 507. The bearing capacity of each pile must be as specified on the submitted plan but in no case less than 12 tons (107 kn). If piles are not driven to bedrock, the Contractor is responsible for performing the dynamic load necessary to determine the required blow count.
Construction of the temporary structure must be according to details and notes shown on the submitted plan. Proposed substitution of elements of equal or greater strength may be made. All other proposed substitutions or changes in design must be submitted in an amended plan meeting the requirements of 501.05.
When the plans permit the use of an existing superstructure as part of a temporary run-around, the bridge shall be relocated so that there will be no reduction in load carrying capacity. The plans for temporary substructure units must be submitted in accordance with 501.05.
The Contractor is required to maintain the temporary structure in good condition with respect to safety, ride quality, and waterway opening for the duration of the run-around. Periodic inspection of the structure must be made and any questionable members or connections that are damaged or over-stressed must be corrected immediately.
1. Document structure and its conformance to the plans
2. Document date installation starts and when the structure is removed