As part of its Accelerated Bridge Program, MassDOT selected the bridge carrying MA Route 7A/Ashley Falls Road over the Housatonic Railroad in Sheffield for replacement. This project employed the use of a new technology developed by FHWA called Geosynthetic Reinforced Soil–Integrated Bridge System (GRS-IBS).
GRS-IBS provides an easily constructible, cost-effective, and durable solution for bridge replacements within specified parameters, placing limits on abutment height, span length, and scour susceptibility. GRS-IBS eliminates the joints, bearings, and the “bump” at the ends of the bridge, reducing structure and vehicle maintenance, and increasing design life compared to conventional construction.
Collins Engineers, Inc. designed the replacement bridge using GRS-IBS technology, and provided engineering services during construction. This was the first application of the guidelines to MassDOT’s standards in the development of plans and specifications.
The replacement bridge has a 40-foot-wide roadway and 6-foot-wide sidewalk. The bridge profile was raised to accommodate a longer span; therefore, roadway work was required on both bridge approaches, extending the project limits 450 feet south and 480 feet north of the bridge.
The new superstructure consists of a 105-foot single span weathering steel multi-girder structure with a reinforced concrete deck. The beam ends are encased in reinforced concrete, serving as both the beam seat and the backwall, which virtually eliminates the potential for beam end corrosion. The GRS bridge abutments are supported by reinforced soil foundations made of geotextile-wrapped aggregate with layers of geosynthetic reinforcing.
With the success of this first implementation of GRS-IBS, MassDOT can apply Collins’ design process to future GRS-IBS projects. It is expected that these types of bridges will have lower initial construction costs and lower future maintenance costs compared to conventional construction.