Maine Demonstration Project: Reconstruction of Lamson and Boom Birch Bridges
SUMMARY OF FINDINGS AND LESSONS LEARNED
The Maine HfL project included the reconstruction of two rural, short-span bridges— the Lamson Bridge near Addison and the Boom Birch Bridge near Old Town. These bridges were deemed to be structurally deficient by the Maine Department of Transportation (Maine DOT).
Key innovations on the Lamson Bridge replacement project included the following:
- Full roadway closures.
- The use of a full system of prefabricated components to accelerate the construction schedule. These included:
- A concrete voided slab superstructure where the precast/prestressed beams functioned as a single unit deck after transverse post-tensioning
- Precast abutments.
- Modular, precast retaining walls that also functioned as return wingwalls
The Boom Birch Bridge replacement project included the following key innovations:
- Full roadway closures.
- Prestressed concrete simple spans on precast, post-tensioned pier and abutment caps.
- Lightweight construction.
- Multiple pile anti-corrosion systems.
A majority of the innovations adopted were primarily aimed at increasing the construction speed.
The following were key observations from these projects:
- The innovations adopted on both these projects helped them meet their accelerated construction schedules with ease. The Lamson Bridge project was completed in 56 days and the Boom Birch Bridge project in 46 days. The estimated construction time for both these projects using conventional construction methods was approximately 270 days.
- Both projects were fully successful in meeting the HfL goals for safety, construction congestion, and user satisfaction.
- For the quality goal, the metrics for noise and smoothness indicated that the Lamson project had a minimally higher noise level and a rougher pavement. On the Boom Birch project, the post-construction noise level was noticeably quieter and the pavement was significantly smoother.
- The durability of both bridges is expected to be superior to conventional cast-in-place construction due to the use of better quality materials and construction procedures.
- On the Lamson Bridge project, it was estimated from an analysis of initial construction and user costs that, using the innovative HfL project delivery approach realized a cost savings of approximately 15 percent over traditional construction methods.
Some of the lessons learned from this demonstration project are:
- It demonstrates that the HfL program concepts of realizing the benefits of accelerated bridge construction do not apply only to large, complex bridge or other horizontal infrastructure projects in urban settings but also to smaller rural bridges.
- The accelerated bridge construction process does offer significant cost savings even on a first-cost comparison basis.
- Early and frequent interaction with the public on the projects improved the public's opinion and overall approval of them.