Each day, approximately 16,000 vehicles travel along the heavy commuter route of Kalmia Road between Silver Spring, Maryland and Upper Northwest Washington, DC. The original stream crossing was already failing due to scour when, in 2010, a storm caused a partial collapse of the culvert. At first, the District of Columbia Department of Transportation (DDOT) shut down one lane of traffic until further deterioration forced closure of the entire road. Rapid bridge construction was determined to be a major requirement for the project due to the lack of nearby roads to cross the tributary to Rock Creek.
Since it was imperative that a replacement structure be installed quickly to minimize the duration of construction, limit the negative impact on traffic to the community and re-open the roadway as quickly as possible, DDOT chose Accelerated Bridge Construction techniques which included the decision to install precast concrete arches, headwalls and wingwalls.
“Due to the heavy volume of traffic, a major challenge was to develop an alternate which would minimize the impacts on the traffic while maintaining the stream and storm drainage flows,” stated Candi Anderson, P.E., Vice President with Mercado Consultants, Inc. (MCI), the project’s engineer. “MCI determined that using accelerated construction techniques would be not only the fastest way of getting the road back into full service, but also provide minimal disturbance to the existing stream.”
A 24’ x 10’ CON/SPAN® B-Series Bridge System, 60’ in length, was selected as the best replacement solution. The precast system met the following requirements: quick installation, low maintenance and an aesthetic look, which was important due to its location in a mainly residential area. Furthermore, the new structure is larger than the original one allowing larger stream flows during storms. Click here to watch a video of the installation.
“The solution provided a larger waterway opening with the expectation that road closures necessitated by flooding during heavy storms would be eliminated,” added Anderson. “Working with the National Park Service, an aesthetic treatment was specified to provide a structure which blended well into the stream setting.”
In order to further expedite the installation, the precast bridge units were placed on approximately 110’ of 4’ wide x 4’ thick precast EXPRESS® Foundations. In addition, 95’ of 4’ wide x 4’ thick EXPRESS Foundations were utilized under 105’ of precast wingwalls. To further enhance the look, texture was added to the headwalls and wingwalls with the use of a formliner and then, to complete the look, stain was applied.
“Without the use of the EXPRESS Foundations, time-consuming (cast-in-place) foundation construction would have been needed extending the duration of the lengthy detour and adding to weary commuter frustration,” Anderson further explained.
During the construction, pedestrians were detoured onto a temporary pedestrian bridge while all vehicular traffic was re-routed via a detour. Upon completion, the new structure eliminated a nearly five-mile long detour. “Considering the harsh winter conditions, I think this was the best and fastest method of construction for this project,” said Mehdi Tasooji, Senior Project Manager with Martins Construction Corp., one of the project’s contractors.
“The precast arch structure allowed us to provide both a cost effective and rapid construction bridge design,” concluded Michael Mercado, P.E., Design Engineer with MCI. “Ultimately, the placement of all components of the bridge was completed in a little over a month. At the project’s completion, local residents expressed their approval of how quickly the bridge was constructed and the overall appearance of the arch and wingwalls, while local officials were pleased that the project came in on time and within the budget.”