by Daniel Whittemore, PE
I find myself more and more having conversations with municipal and DOT infrastructure managers about the impacts that changing rainfall, temperature, and other climate-related hazards are already having and will have on their transportation networks. It makes sense to do that, as the Urban Institute reports that roughly 6% of a typical municipality’s direct general spending is used for highways and roadways. That figure includes the design and upkeep of sidewalks, bridges, roadway drainage, and all of their related structures. With all that 6% has to cover, towns and cities want to ensure that they are making smart investments in infrastructure, including minimizing repair and maintenance needs. And these days, “smart investments” consider both traditional transportation needs and the impact that climate change will have on the function and longevity of these networks.
A number of years ago, I wrote some articles to engage others in a dialog about what a sustainable framework for a typical bridge project might look like. For this exercise, I went with the classic sustainable definition of “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. If such a system existed, I imagined, what topics might it touch on and how would it change today’s standard design process? I envisioned a system modelled after the LEED (Leadership in Energy and Environmental Design) Program for buildings, which is the most widely used green building rating system in the world. The LEED Program attempts to condense sustainable objectives into check-box lists that can be easily compared against an ongoing design to create healthy, efficient green buildings.
For my discussion, I asked the designer to consider these goals:
- Location – Is the bridge sited in the best position possible?
- Water Use and Quality – Does the project best protect water quality both during and after construction?
- Materials – Could bridge materials be reused? Could local materials be specified?
- Energy and Transportation – How does this project capture energy spent both during construction and after the bridge is in service?
If I were creating that checklist today, I would add the additional goal of climate resilience, including:
- Does the bridge design consider changing frequency and intensity of storm events?
- Will the bridge function as a route of egress for evacuation and access for first responders during natural hazards or other emergency events?
- Is the bridge protected against higher future water volume flows concerns such as embankment scour?
As mentioned earlier, municipalities have limited funding and they are often challenged to make that funding stretch as much as possible. Here in the northeast we have experienced a number of superstorms that have devastated communities, wiping out homes and infrastructure. And the cost of cleanup and rehabilitation can be an additional long-term devastation on an already ravaged town or city. I’ve been a part of several bridge projects that seek to implement sustainable design and innovation to both protect and improve local conditions, which are smart investments in infrastructure and use of public funds. In Wellfleet, MA, we are designing a bridge that carries Chequessett Neck Road over the Herring River. After holding workshops with project partners and designing concepts to determine which configuration best met the community’s needs, this bridge was designed with a sophisticated series of hydraulic gates that allow National Park Service scientists to control flows into the marsh system and provide future flood protection for homes and infrastructure around the restored marsh area. The design includes removable flood panels that can be inserted through the bridge and slide gates in some of those panels to provide more finite controls. This unique and project-specific design accounts for both flood control and the sensitive saltwater cove ecosystem downstream from this crossing. This project maximizes capital investment by accounting for both today’s and tomorrow’s needs.
There is not one single solution to combat the effects of climate change. But designing for the effects of future climate impacts as part of already-identified projects is a smart investment into a community’s future and a way to stretch limited public funds.
About the Author
Dan Whittemore, PE is an internationally published author and leader in sustainable bridge design whose work has been incorporated into design standards by many agencies and municipalities, most notably the 2015 Iowa Department of Transportation’s Bridge Design Manual. He is a Senior Structural Engineering in Fuss & O’Neill’s Bridges and Structures Department and brings his 20 years of experience to building the transportation landscape of New England.