Maplewood Avenue Bridge Rehabilitation, Portsmouth, New Hampshire

The Maplewood Avenue Bridge Rehabilitation Project addressed critical structural, safety, and operational deficiencies associated with a historic transportation asset serving the City of Portsmouth, New Hampshire. Originally constructed in 1896, the stone arch bridge exhibited advanced deterioration, reduced load-carrying capacity, and advancing roadway distress related to a deteriorated corrugated metal plate arch liner installed during a prior rehabilitation. The project was further constrained by tidal hydraulics, environmental and historic regulations, and the need to maintain pedestrian access throughout construction, requiring a carefully coordinated and technically rigorous rehabilitation strategy.

Hoyle Tanner served as prime consultant to lead the evaluation, design, permitting, and construction-phase support. Hoyle Tanner developed an innovative, preservation-focused solution that restored full structural capacity using a thin, spray-applied geopolymer liner while maintaining the historic masonry arch and matching existing hydraulic performance. GZA GeoEnvironmental supported the project as the geotechnical engineer, and Headwaters Consulting LLC performed hydraulic analyses and supported permitting coordination. Through close collaboration with the City and regulatory agencies, the project was delivered efficiently, extending the bridge’s service life by decades and resulting in a durable, sustainable infrastructure improvement that meets the City’s long-term transportation and asset management goals while maintaining an important historic resource.