The appropriate method to be used for culvert rehabilitation depends upon the type and size of the culvert, its condition, and hydraulic and economic considerations.
Hydraulic and economic considerations bear on the issue of repair versus replacement. If the hydraulic capacity of the culvert is in question, or if a rehabilitation method that would reduce its capacity—either by reducing the waterway or by increasing its roughness—is under consideration, a hydraulic analysis is required. In addition, if there will be additional highway construction in the area or if there are plans to widen the roadway in the future, these considerations should be included in the decision of rehabilitation versus replacement.
Pipe replacement is the only method applicable to all pipe types regardless of defects. It is also the most disruptive to the traveling public if done using an open-trench method of construction. As has been previously discussed, jacking or tunneling, at an increased cost, may eliminate this disruption. The advantage is that the hydraulic capacity may be increased and, at the present time, replacement is comparable in cost to relining. However, other methods of rehabilitation will often suffice, as discussed below.
