McMahon, as a subconsultant, provided significant contributions to the improvement plan for this project known locally as the Route 128 Add‐a‐Lane Project. The improvement plan involved the 3.5 mile section of I‐95 north of Route 135 to the Route 9 interchange.
McMahon prepared the Functional Design Report (FDR) and worked with the Central Transportation Planning Staff (CTPS) in conducting the final traffic model runs for the improvement scheme.
The improvement plan comprised the following elements:
- Adding one travel lane in each direction on the mainline
- Providing a new interchange at Kendrick Street
- Installation of a collector‐distributor roadway between Kendrick Street and Highland Avenue
- Traffic signal work on Kendrick Street and Highland Avenue
- Improvement of the Route 9 and Highland Avenue interchanges
Capacity analyses were conducted and improvements developed for both the freeway components and the secondary corridors. Traffic signal work included the design of three new traffic signals, two coordinated signals at the modified Route 9 interchange and one at the proposed Kendrick Street interchange, and the modification of three existing traffic signals within the study area.
For the Route 9 interchange, McMahon completed traffic analyses for the no‐build alternative and five design options and prepared the FHWA Interchange Justification Report (IJR) with supplemental technical analyses. As part of the design review process and community outreach, VISSIM analysis was used to refine and evaluate the design concepts in the vicinity of the Route 9 interchange. McMahon worked with MassDOT on the construction staging and development of the traffic management plans, major components of the project work.