Spanning 1,828 feet diagonally across Maine’s St. John River, the new Madawaska-Edmundston International Bridge is a six-span steel girder structure designed to serve the border communities of Madawaska, Maine, and Edmundston, New Brunswick, for the next century.

The crossing requires minimal maintenance and supports multimodal travel with two 12-foot-wide lanes, 6-foot shoulders and a dedicated 6-foot-wide sidewalk for pedestrians.

As impressive as the structure itself is, the story behind its creation is just as compelling.

Renewing a vital link

The Madawaska-Edmundston bridge is more than a commercial corridor and U.S.-Canada crossing — it’s a vital link for communities that have functioned as one for more than a century. Many residents of the region have family members on each side of the bridge. Some live on one side and work on the other. The towns even share public services, such as emergency services and waste removal.

When the original bridge, which opened in 1921, was nearing the end of its service life, the Maine Department of Transportation (MaineDOT) implemented an ambitious campaign that allowed a new bridge to be designed in two years and constructed in less than four years. MaineDOT was determined to mitigate the hardship of a decades-long bridge replacement project. MaineDOT partnered with HNTB to evaluate alternatives and rapidly design the replacement bridge.

Designing across boundaries

In August 2018, the team began preparing preliminary designs and coordinating an extensive cross-border collaboration led by MaineDOT and the New Brunswick Department of Transportation and Infrastructure.

Design and constructability decisions considered several factors. The new bridge site was on a steep, unstable valley with heavily fluctuating river levels.

The bridge needed to be built with access through and around an active paper mill — the region’s largest employer — operating on both sides of the St. John River. It also needed to accommodate two independent railroad yards and a highly secure, active international border crossing.

“Designing an international bridge involves many stakeholders on both sides of the border,” said Josh Olund, HNTB project manager. “The Madawaska-Edmundston International Bridge was even more unique in that the stakeholders also included railroad operators, the Twin Rivers Paper Company, which has operations on both sides of the border, the First Nations indigenous community, among others who utilized this bridge for their daily needs. HNTB and our partners held numerous coordination meetings and several bilingual public meetings to ensure the project met the needs of the communities.”

After narrowing the design options to a steel girder bridge and a cast-in-place segmental concrete bridge, HNTB submitted plans for the preferred alternative: a six-span steel girder bridge. It was chosen for its lower construction risk, cost-efficiency and accelerated schedule.

The site complexity was heightened by the simultaneous construction of a new U.S. Land Port-of-Entry (LPOE) facility, a quarter mile upstream from its current location, and the redevelopment of the Canadian Port of Entry (POE) site to align with the new north end of the bridge. In total, three major concurrent construction projects were underway within a half-mile area.

The new U.S. LPOE location also meant the new bridge would need to be nearly twice as long as its predecessor so that it could tie into the existing Canadian POE. The team implemented a diagonal crossing, angling the bridge at a 45-degree angle, to connect the two port facilities. This innovative alignment preserved critical land uses, allowing both ports to remain operational during construction. It also yielded some of Maine’s longest steel spans, reaching up to 315 feet.

Because the bridge links these two port facilities, access for maintenance required heightened coordination from both countries. To minimize maintenance needs and ensure resilience, the structure was built with durable, sustainable materials: unpainted weathering steel, stainless-steel rebar, ice-resistant pier casings and long-life LED lighting. Wider lanes and shoulders enhanced snow removal and drainage, supporting efficient long-term operations across borders.

“HNTB was very involved in coordinating MaineDOT’s andNew Brunswick’s interests, the security needs of Customs and Border Protection and the municipalities during the feasibility portion of the project,” said Andy Lathe, senior project manager in MaineDOT’s bridge program. “They had more than 20 proposed alignments and were able to collaborate with all entities to arrive at the preferred alternative.”