Safety roadmap: New manual for Maine road crossings impacted by climate change
Courtesy / Matt Craig, Department of Marine Resources
Most bridges and culverts on roads that cross salt marshes and tidal waterways aren’t equipped to handle the ebb and flow of the tides.
Ninety percent of bridges and culverts on the roads in Maine that cross salt marshes and tidal waterways are not equipped to handle the ebb and flow of the tides.
That leads to higher road maintenance costs, a shortened lifespan for culverts and bridges, unplanned road closures that can put public well-being and safety at risk, and harm to commercial fisheries and important habitat.
That’s why the Department of Marine Resources' Maine Coastal Program, along with 30 other organizations, published a 100-page manual offering technical guidance on how to increase the safety of road crossings over Maine’s coastal wetlands and waterways.
“The CoastWise Approach: Achieving Ecological Resilience and Climate-Ready Road Crossings in Tidal Environments” was desiged to be a resource for municipal and private engineers, public works directors, land developers, landscape architects and habitat restoration practitioners, said Maine Coastal Program Director Kathleen Leyden.
The publication may also be of use to general audiences and those working to build community awareness — such as local elected officials, neighborhood associations, conservation commissions, land trusts and the public, she added.
The manual provides information about tidal wetlands and the factors that are changing them.
“Safe, dependable roads are crucial for supporting Maine’s economy, access to critical services, and a way of life valued by citizens and visitors alike,” said Leyden. “The severity of today’s tidal restrictions is likely to worsen as sea levels rise and the volume of water flows increases over the coming decades.”
The challenge
Safe, dependable roads are considered crucial for Maine's economy and access to critical services. Maintaining roads is a challenge for most communities in Maine, especially in coastal areas experiencing rapid change due to accelerated sea level rise.
Where roads cross tidal wetlands at over 800 locations in Maine, the challenges are considerably magnified.
Tidal wetlands can provide coastal storm and flood damage protection, pollutant filtration and breakdown, fish and wildlife habitat, commercial harvesting and recreational opportunities.
Some wetlands, like salt marshes, store atmospheric carbon that would otherwise contribute to sea level rise and other climate shifts.
To deliver those benefits, tidal wetlands must remain healthy and resilient to sea level rise. That requires unimpaired tidal flow.
But about 90% of Maine's tidal road crossings are tidal restrictions. The crossings put Maine's tidal wetlands at risk, but are also more apt to experience flooding, higher maintenance costs, and interrupted access to emergency services.
Tidal complexities
Traditional practices for designing tidal road crossings don't adequately address the unique complexities, uncertainties, risks or benefits associated with tidal environments.
In response, the Maine Coastal Program and the CoastWise Steering Committee convened experts in the field and marshaled the input of over 30 organizations to develop the CoastWise manual, which discusses tidal wetlands as dynamic systems influenced by a wide range of interacting social and environmental factors requiring a design approach that addresses complexity and risk, now and in the future.
The free publication offers best practices to help road owners, municipal staff, engineers and others in helping to replace tidal road culverts and bridges with safe, climate-resilient crossings, she said.
Partners involved in the project are developing training modules, which are anticipated to be held in 2024.
To view the manual, click here.
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