Interested in reading Part 1 of the series? Go to Engineering for Transit Route Decisions Part 1
When making transit route plans that will affect the citizens and footprint of a community, many factors come into play. The first considerations are ridership demand factors, like density of communities, an optimal/efficient route to serve riders, and understanding the types of riders that may take advantage of a particular transit route.
Once those factors have been identified and synchronized into a big-picture concept of a transit route, the next details that come into play are based on route alignment, which includes design, timing and jurisdiction.
While ridership is an important factor in determining the size of vehicle needed—as vehicle capacity can range from a small passenger van to a larger 60’ articulated bus that can carry up to 70 people—there is another important question to consider: Can the vehicle navigate the streets? When designing a route, narrow city streets, tight intersections, speed bumps, and unsignalized left turns create obstacles that can slow down the route or add wear and tear on the vehicle. Another design obstacle is where to turn the route around. In urban areas, it is often easy to find a grid pattern or transfer facility location that allows the vehicle to begin its return trip; however, in suburban areas, the end of the line may be a shopping center, which requires the vehicle to enter private property. Communication is critical to help the property owner understand the benefits the service brings to customers and employees versus perceived negative impacts.
Timing is another important detail in developing a successful transit route. Service frequency (how often a route comes by a given stop) can influence the productivity of a route; however, an agency must balance the design of the route and budget allocated to operate the service. If an alignment is long, or experiences heavy traffic and slow speeds, more vehicles are needed to meet a given frequency. Each additional vehicle increases the operating cost of a route. Ideally, a route should provide well-timed connections to other routes. These considerations may require looking the system as a whole to ensure vehicle utilization and routing is as efficient as possible, often by conducting a Comprehensive Operational Analysis. Davis & Floyd is currently working on a plan for the Charleston Area Regional Transportation Authority (I-26ALT Project), where traffic congestion has created timing delays for many of the agency’s most productive routes; however, no new operating revenues are available to add service. Our team is looking at system strategies to improve route performance without impacting the growing demand for transit in the service area.
Lastly, jurisdictional boundaries are often where the rubber meets the road in establishing a desirable transit route. For example, say a commuter travels from her home to her job – she may live in Lexington County but work in Columbia, South Carolina, which is in Richland County. Because transit is typically subsidized with local revenue sources, a route may end at the jurisdictional boundary. In South Carolina, these boundaries are often county lines. This is the biggest route alignment issue for customers to understand since it’s an “invisible barrier” for transit routes.
Once we’ve sorted through the alignment factors and come to a plausible and successful route that optimizes ridership, meets logistical needs and works within designated boundaries, transit planners are on their way to making these plot points a reality.
In Part 3, we’ll describe last-mile connectivity, the infrastructure that relates and leads to the route—things like sidewalks, bike lanes, shelters, and park and rides—that are a crucial last step for success.
About the Author — Sharon Hollis, AICP, is a Senior Transportation Planner with Davis & Floyd who is responsible for project management and planning support for a range of local and regional transit planning studies in rural, suburban and urban settings throughout the country.