Hoyle Tanner is proud to announce that the Maplewood Avenue Bridge Rehabilitation Project in Portsmouth, New Hampshire has earned a Silver Award in the Engineering Excellence Awards presented by the American Council of Engineering Companies of New Hampshire.
The Engineering Excellence Awards (EEA) are a benchmark for achievement in the consulting engineering profession, recognizing projects that demonstrate innovation, technical complexity, and meaningful community impact, while highlighting the collaboration between project teams, clients, and agency partners.
Originally constructed in 1896, the Maplewood Avenue Bridge is a historic stone arch structure that serves as a vital transportation link for the City of Portsmouth. Over time, the bridge experienced significant structural deterioration, reduced load capacity, and roadway distress due to a failing corrugated metal plate arch liner installed during a previous rehabilitation. The project required addressing complex tidal hydraulic conditions, navigating environmental and historic preservation regulations, and maintaining pedestrian access throughout construction.
As prime consultant, Hoyle Tanner led the evaluation, design, permitting, and construction phase services. The team developed an innovative, preservation-focused solution centered on a spray-applied geopolymer liner installed within the existing corrugated metal plate arch. This approach restored structural capacity with a significantly thinner, less labor-intensive system compared to traditional sliplining, and at a fraction of the cost of full replacement.
Additional targeted improvements enhanced performance, constructability, and aesthetics. Polyurethane grout was injected into the surrounding roadbed to fill voids and stabilize the roadway without extensive excavation. The roadway profile was also raised at the bridge to increase cover over a reconstructed water main and to improve stormwater collection through a steeper profile. Distressed granite block headwalls and wingwalls at each approach underwent reconstruction to restore the stability and appearance of the corridor.
The project’s success reflects strong collaboration with partners GZA GeoEnvironmental and Headwaters Consulting LLC, along with close coordination with the City of Portsmouth and regulatory agencies. By extending the bridge’s service life by decades while preserving its historic character, this project delivers a resilient, cost-effective, and sustainable infrastructure solution that supports the City’s long-term transportation and asset management goals.
Hoyle Tanner is honored to be recognized alongside our partners for delivering a project that brings together technical excellence, innovation, and thoughtful preservation.
