The Maine Turnpike Authority (MTA) planned to upgrade the Saco Toll Plaza’s toll systems as part of a system wide improvement, and that required closing a toll lane during construction. To maintain three functional lanes during construction, an additional toll lane was needed, and was needed quickly.
We were hired to develop the design and contract documents for this toll lane addition. In seven months our team developed the project from concept to 100% PS&E. We reported on highway and toll plaza geometric design, drainage design, structural gantry and overhead sign support design, guardrail design, geotechnical analysis and design, maintenance of traffic, signs and pavement markings, toll systems coordination, utility coordination, environmental resource identification, and permitting.
Using subsurface investigation, laboratory testing, and geotechnical analysis, we predicted that the additional load from a conventional earth embankment fill would cause settlement up to 13 inches. The solution? Blocks of lightweight geofoam were used to partially offset the weight and reduce the magnitude of the settlement.
With our team’s work, the MTA was able to manage traffic during construction and eventually improve conditions at the Saco Toll plaza.