Case study: Paving the way for future-proof, equitable transportation infrastructure

Summary

The Region of Durham wanted a better understanding of how vulnerable its transportation network was to future flooding, so staff performed a flood risk assessment to aid in future decision-making and resilience planning. The assessment is a 2024 Sustainable Communities Awards winner in the Reconciliation and anti-racism, equity and inclusion (AREI) category thanks to its innovative use of a social equity lens to ensure that transportation planning considers the needs of more-vulnerable communities. The Region is now using this risk assessment to help inform asset management priorities and has shared its work to be replicated elsewhere.

The challenge  

The Region of Durham, located east of Toronto, encompasses eight rural and urban municipalities with a total population of about 750,000 that is predicted to grow to 1.3 million by 2051. Durham experiences regular flooding and projections for the region indicate upcoming surges in storm severity and frequency, winter rain and freeze-thaw cycles.  

By conducting flood risk assessments, the region can plan for protective measures to make its 2,500 lane kilometres of roads and 250 bridges and culverts more resilient to potential flooding. Other specific challenges Durham wanted to address include:

• The high cost of maintaining transportation infrastructure and dealing with the effects of flooding. Having as much data as possible to set priorities helps keep budgets efficient over the long term.
• The effects of flooding that worsen existing inequities, such as when residents lose transportation options that are already limited.

The approach

Durham worked with multiple partners including local conservation authorities and municipalities to gather and analyze already existing flood- and climate-related data as well as output from climate prediction tools. Staff with practical experience dealing with flood impacts were included in the process.

Social equity was not initially part of the project. However, staff quickly realized it was needed and worked with Durham Social Services and the Durham Region Health Department to build it in.

“Not all communities are equally prepared to deal with climate change, so the equity lens is very important.” 

– Mani Rajendran, Senior Project Manager, Transportation Design and Chair, Transportation Resilience, Region of Durham 

Together, they built a scoring system for the assessment. The idea was to better prioritize flood-vulnerable roads near communities that already face multiple barriers and might need additional assistance during flood events due to limited accessibility, mobility, support networks, financial resources or other issues. The Region’s social services and health teams contributed with community health and social equity indicators including low-income, unemployment, mental health, Indigenous population, visible minorities and seniors living alone. This information was scored and averaged by neighbourhood and then added to the overall score of nearby transportation assets. This gave planners relevant details on equity-related needs.

While considering the socioeconomic impacts of road network flooding, the assessments also prioritized the community’s most critical transportation routes, which include:  

• major commuter routes
• transit routes
• goods-movement routes
• remote communities that do not have alternative access routes
• those serving essential facilities such as hospitals, child care, schools, retirement homes, emergency services, power plants and community services.

The solutions and results

Durham’s completed assessments identify vulnerable water crossings and roads under current and future flood scenarios. This information will help staff and elected officials make data-driven decisions on improving the transportation system’s adaptive capacity and resilience. Specific results include:

Environmental:

• A better understanding of high-priority assets for mitigation work to reduce the overall impact of flooding both on infrastructure and on nearby communities.
• Better flood risk data now available to numerous conservation authorities and local governments thanks to a collaborative approach.  
• Predicted reduction in greenhouse gas emissions from stalled vehicles due to fewer road closures and delays thanks to improved management of transportation assets.

Economic:

• Reduced financial and legal risk to the Region.
• Better, data-informed decisions on how to plan for flooding will lead to cost savings from vehicle traffic delays and disruptions thanks to fewer road closures.
• Increased budgetary efficiency:  
  • Routes that are already sufficiently protected have been identified, freeing up resources for other areas.
  • Climate change impacts and adaptation measures can more accurately be considered in infrastructure financing, resulting in more strategic and forward-thinking decision-making.

Social:

• A better understanding of how to reduce the socioeconomic impacts of flooding on road networks.
• Equity-oriented prioritization of roads for future resilience measures, including those identified as designated transit routes.

Lessons learned

By collaborating with conservation authorities, local municipalities and experienced consultants, the Region was able to leverage and analyze existing data to create predictions and assess risk without having to gather new data or develop new climate models. This close collaboration model has also had the benefit of obtaining early buy-in from all partners and the ability to team up to push initiatives forward.

Flood risk data is now incorporated into the Region’s corporate asset management information systems, which enables transportation infrastructure project managers to more easily consider options to improve flood-vulnerable locations using a scientific and systematic process.  

One factor that helped the project succeed was support from organizational leadership, who were able to ensure the risk assessment was seen as a priority by everyone involved.

“It doesn’t have to be all or nothing. We don’t have to build big, expensive bridges to solve the problem or do nothing because of lack of funding—we can build relief culverts to solve most of the problem or buy time.”

– Mani Rajendran, Senior Project Manager, Transportation Design and Chair, Transportation Resilience, Region of Durham 

Next steps

Durham’s flood risk assessment process has been replicated several times elsewhere, including by the Central Lake Ontario Conservation Authority and the Ganaraska Region Conservation Authority, and has inspired work in other Canadian municipalities as well.  

Internal next steps include developing guidance and training materials for decision-makers and staff on how to use the data, and beginning an assessment of emergency and evacuation routes.

The Region is exploring how to use socioeconomic mapping in other areas, such as for home retrofit programs, while feeding the flood risk assessment data into decision-making such as finding safe sites for hazardous waste facilities. In addition, staff are cross-referencing the Region’s risk assessment and current 10-year capital plan to inform the design for community-centric transportation needs and priorities, such as key flood-vulnerable road segments and road crossings.