When the nimbleness of a transportation network is tested, it’s rarely by an expected event—which is why it’s critical for communities to plan for the unpredictable and build resilience into our transportation systems.
At its core, transportation resilience is about systems working together to provide flexible and resilient infrastructure that helps people move safely through natural disasters or other major challenges. It means planning ahead and being thoughtful about our long-term infrastructure and investments. This form of planning finds us assessing how a corridor can be used for multiple purposes, coming up with solutions if it breaks down, and creating pre-disaster risk mitigation strategies to keep people moving safely if a major event happens.
Resilience is an essential element of an economically efficient and sustainable transportation network. Transportation engineers and planners should look for ways to do more with less to allow individual investments to be leveraged, thus maximizing limited resources. For example:
- A transportation corridor can be designed for mobility and access and also temporarily channel overflowing water.
- A public open space can be used as a community park and also be designed to hold and accommodate temporary flood events.
- A buffered bike lane can support active transportation and also be flexible to accommodate other modes during an emergency event.
- A resilient transportation network can accommodate increased infrastructure use as a community grows.
- A resilient project incorporates redundant networks and mitigation strategies, thus avoiding gridlock in emergency events.
Incorporating resilience into a transportation system requires modeling and scenario planning around different futures, and often developing alternative sets of solutions to events before they happen. It means looking at our streets and coming up with thoughtful, informed approaches to situations in which crashes, weather events, or major construction projects may prevent us from moving around and accessing daily needs safely. Nimble strategies are particularly useful during evacuation cases when people, goods and emergency providers need to travel in one direction without being inhibited by congestion.
The Importance of Nimbleness in Transportation Resilience
Different emergency situations call for different modes of transportation. In a flooding scenario, an above-ground bus is nimbler than a below-ground train. However, in the event of an evacuation, a train could move more passengers than a bus on a choked freeway. If public transit goes completely offline, bikes, electric scooters, and walking can play an important role in moving people around.
A diverse transit infrastructure that supports different forms of transportation gives people options during an emergency event and provides alternatives to car ownership.
Alerting residents and commuters to transportation outages is another component of a strong and resilient transit infrastructure. For example, when transit service shuts down, broadcasting closure information, along with alternate routes, keeps communities moving safely and efficiently.
Perhaps the most critical form of transit resilience planning is evaluating the current infrastructure for vulnerabilities. When we think about infrastructure, we think about how it performs through extreme conditions. Most transportation systems require power, so when electricity goes out, we need to know how to keep vehicles moving carefully during a weather emergency or other major disaster. A thorough transportation resilience infrastructure assessment should ask these following questions:
- What can be done to protect existing evacuation routes? What alternatives exist or need to be created?
- How can a transportation corridor or transit service perform double duty?
- How can access to essential assets such as hospitals, drinking water sources, and energy be secured by proactive planning?
- Should certain essential services or evacuation routes be relocated to lower-risk areas?
- How can existing infrastructure be utilized in an emergency? For example, can local open space areas temporarily capture or hold stormwater?
- What are the pros and cons of restricting or dis-incentivizing development in areas prone to flooding or landslides?
Transportation Resilience and Hurricanes
Hurricane Florence inundated Wilmington, North Carolina with more than 20 inches of rain over five days in 2018. Power outages knocked out the majority of the city’s 221 traffic signals, leaving six and eight-lane arterials without traffic control. By NC statute, these intersections became four-way stops, but poor visibility and lack of compliance lead to severe crashes. A Wilmington Police Department Traffic Enforcement Officer suggested a solution: roundabouts. At intersections in which these temporary roundabouts were installed, no severe crashes were reported. After helping the City of Wilmington analyze the results of this quick and efficient solution, we assembled a series of lessons learned that other communities can apply if they experience similar obstacles.
It’s important to make sure every community has traffic mitigation tactics in place before a disaster happens. When Kittelson worked on evacuation planning in Florida before Hurricane Irma, we used hard shoulder running as one of our traffic mitigation strategies. This tactic uses the outside lanes of a freeway typically used for emergency or distressed vehicles as another resource for passage. We opened one lane to allow private vehicles through, and another one specifically for emergency vehicles to keep vehicles moving.
Hard shoulder running is an adaptable and nimble transportation solution. That same solution can be used by agencies for bus services at peak hours during commutes to alleviate traffic. It’s a technique that approaches resilient planning from the perspective of sustainability to make transit services more efficient and reducing cars on busy streets.
Transportation Resilience and Flooding/Sea Level Rise
Many communities increasingly face flooding challenges as routine and not once-in-a-lifetime events. Flooding can render roads, tunnels, airports, seaports not usable, stranding populations and keeping vital functions of a city from functioning.
When new communities are built, or streets revamped, flood and stormwater mitigation should be part of the planning and design process. In addition to storm events, sea-level rise is placing a heavy burden on coastal communities. Continued rise in the water table means those communities will take longer to “dry out,” they will be less responsive to back-to-back storm events, and the existing stormwater facilities will be at capacity even before the hurricane hits. Incorporating innovative “Green Infrastructure” like rain gardens, pervious pavement, and/or bio-swales when designing transportation facilities may cost more in the short-term, but that green infrastructure can save millions in repair and maintenance costs in the long run.
Many communities increasingly face flooding challenges as routine and not once-in-a-lifetime events.
Kittelson recently worked on a Complete Street project in Melbourne, Florida that because of poor soils and existing drainage issues, required application of some of these green infrastructure strategies. Our assignment was to re-design the pedestrian-active Hickory Street to include sidewalks, bicycle lanes, landscape beautification, and make it more resilient and fix the existing drainage issues.
We considered various flooding scenarios (a 100-year flood, rising sea levels vs. rising groundwater, etc.) and applied a series of coordinated solutions. Rain Gardens were introduced in the non-curbed portions as an aesthetically pleasing method of collecting stormwater runoff. In another area that floods regularly, we designed and constructed the street using porous paving materials. The additional 8-10 inches of porous pavers help to serve as a pseudo-retention area to hold flood water until it can seep back into the ground. This solution mitigates a variety of drainage issues by not only replacing the existing impervious surface, but also lifting up the driving, bicycling, and walking surface without creating additional impervious surface or compacted soil—and it keeps people moving by preventing flooded pathways and streets.
Transportation Resilience and Fire-Related Threats
On the West Coast, fire and landslides are two of the greatest threats to communities and their transportation infrastructure. A resilient transportation infrastructure includes multiple evacuation routes and a variety of options people can use for safe travel. Critical routes on the transportation network should be placed on a regular inspection and maintenance schedule even if an event isn’t expected. This includes evaluating areas susceptible to landslides due to increased groundwater use, or those that could be, or have been damaged by fire.
We can take notes from the City of Berkeley, CA, which offers a free Community Emergency Response Team training. The program provides education in disaster preparedness and provides training in basic emergency skills. By preparing neighborhoods and community groups with emergency skills, we can lessen the effects of a disaster and help sustain ourselves until assistance can arrive. The City regularly holds emergency prep fairs and citywide exercises, and recently the Fire Department organized a full-scale BART drill which simulated an emergency in the Berkeley BART tunnel system. Additionally, the City recently published the draft Local Hazard Mitigation Plan in an effort to reduce physical vulnerabilities.
The Transportation Industry is One that Looks to the Future
Whether it’s retrofitting areas, disaster mitigation planning, or looking at how community streets can become more resilient, we must think about how our streets today, and in the future will be used for more than just moving cars. As transportation consultants, it is our job to help agencies and local municipalities meet the needs of their communities with safer and more efficient transportation. This means proactively planning for how transportation networks can adapt to future realities, from gradual sea level rise to a sudden evacuation. Our transportation projects today must create long-term sustainable futures in our communities and for future generations.
Start a conversation with us to talk more about resilient transportation planning and how we can work toward creating transit networks that last.