GIS Data Collection of Culverts

About the Program

Category: Transportation (Best in Category)

Year: 2017

Culverts are conduits that convey stream flow or storm water runoff from one side of a road to the other side. They are typically metal or concrete pipes or concrete boxes. Very large culverts are categorized as bridge structures. If not maintained, culverts, especially metal ones, will erode, deform, and fail. The failure of a culvert usually leads to the loss of roadway fill and pavement failure and often requires unexpected road closure for safety reasons. Repairing culverts before total failure provides substantial cost savings and minimizes disruptions to traffic. Montgomery County Department of Transportation (MCDOT) had an incomplete database of all the culverts in the county and often operated in a reactionary mode to implement emergency replacement of previously-unknown, failed culverts. This reactionary mode of operation was very costly, disruptive to existing vehicular and pedestrian traffic, and required a distressful search for emergency funding. MCDOT staff expedited a new program to collect GIS data of all publicly-maintained culverts in the county. This asset inventory provided information on type, size, location and condition of all culverts in the county and allowed staff to develop a schedule for maintenance, repair, or replacement action, as needed. This program successfully located and assessed the condition of 220 previously-unknown large culverts (bridges) and 193 smaller culverts. Although the cost of repairs can vary for each culvert, on average rehabilitation of large steel culverts (before full failure) costs $200k or less; the duration to develop the design and secure the needed permits is less than 6 months, and the construction has minimal impact to existing traffic and takes only two weeks to complete. By comparison, a fully failed large culvert requires replacement or complex rehabilitation, which takes 18 to 24 months for plan and permitting, has an average price of $1M, and a more disruptive and longer construction duration. This program has provided very valuable information and resulted in cost savings of millions.