Bridge: Construction Staging

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Construction Staging

Primary Guidance

  • When a bridge is being replaced or rehabilitated, the number of construction stages should be kept to a minimum.
  • Whenever possible, bridges should be closed and traffic detoured during construction.
  • BridgeA structure including supports erected over a depression or an obstruction, such as water, highway, or railway, and having a track or passageway for carrying traffic or other moving loads, and having an opening measured along the center of the roadway of more than 20 feet between undercopings of abutments or spring lines of arches, or extreme ends of openings for multiple boxes; it may also include multiple pipes, where the clear distance between openings is less than half of the smaller contiguous opening. For lengths, all dimensions shall be parallel to the center line of the roadway. The dimensions of handrails will not be taken into account in measuring bridge lengths. Any bridge or highway grade separation structure includes the connecting highways, substructure, superstructure, roadway approaches, entrance plazas, interchanges, overpasses, underpasses, and other structures which the Administration may deem necessary together with all property rights, easements, franchises, and interests acquired by the Administration for the construction and operation of the bridge. substructures and superstructures should be designed to facilitate staged construction for a future deck replacement.

Discussion

Stages of Construction

When a bridge is being replaced or rehabilitated, the number of construction stages should be kept to a minimum, which will reduce the bridge cost and construction duration. Consider reducing the number of lanes being maintained and lane widths to accomplish this. If possible, avoid a situation where there is a construction zone in between travel lanes. This would make construction more difficult, increase the cost, and decrease safety for construction personnel and the traveling public.

Detours

Whenever possible, the bridge should be closed during construction and traffic detoured. This provides the shortest construction duration and lowest project cost while ensuring the safest project. For example, consider a detour for projects where the bridge can be constructed over the summer months when school is not in session and traffic needs are less. A detailed Maintenance of Traffic Alternatives Analysis should be performed when a detour is considered to ensure minimum mobility thresholds can be met. Consider drive by businesses that will be bypassed by the detour as well. A contractor incentive/disincentive to open the bridge to traffic on time should also be included in the project to minimize the impacts to the traveling public.

Future Deck Replacements

In order to address maintenance of traffic during a future bridge deck replacement, all substructure units on new bridges should be designed to support full live load with portions of the superstructure completely removed. If it is not apparent how many lanes may need to be maintained in the future, assume the bridge deck will be replaced in half sections for the purpose of the design. Piers should be configured so that temporary supports of pier caps will not be needed during staged construction. Where possible, the superstructure of the bridge should be arranged so that at least three beams will be supporting the deck in each stage of construction. Supporting the deck on two beams may not be a stable configuration, especially if curved girders are involved, and should be evaluated to determine if additional supports are required.

See Also