Complete Streets Design in High Volume Corridors

Our country was founded on the ability to travel vast distances as quickly and efficiently as possible. The building of roads often took precedence over concerns for other modes of transit due to the profitability of trucking and the need for commercial growth. Planning for all travelers took a back seat until economic, social, and environmental factors merged into the complete streets movement early this century.

In the mid-2000s, divergent advocacy groups from bicyclists, seniors, minorities, and even realtors started coalescing around the idea of smart street planning. Although federal complete streets legislation failed to pass into new laws, its central tenets filtered to local, regional, and state agencies that saw a groundswell of support for more complete street projects. The National Complete Streets Coalition reports that 448 regional and local jurisdictions, 27 states, Puerto Rico, and Washington, D.C. have adopted complete streets policies, with many more adopting non-binding resolutions supporting smarter transportation planning.

Approaching a new or upgraded street design often starts with creating space for all desired transportation modes. Creating street zones in roadways for pedestrians, bicycles, and vehicles (including public transit) can be a challenge in narrow corridors. Deciding when and where these priority street elements should exist, their minimum and preferred widths, and other design elements that can or should be included require coordination and diligent planning.

Part of the planning starts with assigning street designations for each roadway in the plan. For example, mixed-use streets have access to vehicles, people, parkland, commerce, and public transportation. This is contrasted with residential and green-style parkways that offer more opportunities for pedestrians, bicyclists, and landscaping. Other considerations for each street designation include lane widths, right-of-way allocations, and typical traffic volume.

Another challenge in achieving balance is where to place the pedestrian zone (sometimes called the public realm) in relation to other street elements including the roadway, parking, greenspace, and frontage, i.e., shops and homes along the street. Another frequent request of smart street planners is to incorporate more greenery into our communities, both for aesthetics and cleaner air. The increased shade opportunities are also recognized as a benefit to provide relief to citizens in extreme heat conditions.

Achieving optimal traffic flow of vehicles, bicycles, and pedestrians should be a part of any connected city design. Taking a holistic approach to how all the elements move within a traffic grid by considering how turns, signals, walkways, and signals interact is vital for the safety and free flow of all types of traffic.

One aspect of achieving an optimal traffic flow pattern is target speed – the pace you want a person to drive. Target speeds should balance the needs of all anticipated street users. Matching design to driver expectations, the target speed should match the posted limit. Traffic studies are helpful to determine the volume and safe speeds.

There are smart street design elements that help speed up or slow down traffic depending on what is needed. For example, coordinated traffic light patterns will efficiently move traffic through crowded downtown streets. Slowing down traffic can be accomplished using chicanes, pinch points, corner islands, turn wedges, and roundabouts. There are also opportunities to add more green space and parkland to communities while calming traffic in these plans.

Safety is of utmost concern for complete street designers and engineers. Citizens need to feel they can move about knowing they and their families are safe. But what do transportation professionals look for in safety improvements while building complete streets in high-volume corridors?

Along with studying and implementing road designs that provide optimum speed limits and other speed-related elements like roundabouts, designing streets for pedestrians and bicyclists, including sidewalks, raised medians, curb extensions, and bus pullouts all improve safety. Pedestrians benefit from crossing an intersection in a single cycle, rather than two cycles for example. And providing safe bicyclist accommodation needs to consider how to accommodate cyclists who don’t feel safe or comfortable on streets shared with motor vehicles.

Finally, one of the most critical policy effects from the Americans with Disabilities Act (ADA) is the proliferation of design elements for seniors and the disabled. High-volume corridors need more comprehensive public transportation access points, bulb-outs, pedestrian refuges, and smaller curb radius to reduce vehicle access and improve pedestrian-friendly areas.

While much of the focus of complete streets is on cities or busy commercial areas, growing suburban and exurban zones is where smart planning can significantly impact the future. Planning for population growth in the beginning phase of road design, including bike paths, walkways, and green space is frequently requested by municipalities. Adding additional road lanes is also top-of-mind when creating a holistic plan for complete streets to anticipate higher volume in growing areas. Even existing, high-volume corridors can benefit from full street design to widen walking and cycling lanes where additional space is available.

These new transportation corridors can also see improved connections to urban areas. The need for bus, rail, and commuter parking lots connects residents to urban cores while keeping cars and trucks off the roads to improve air quality and overall traffic conditions. Planning for these commuter services like light rail or bus rapid transit is increasing in popularity but can be challenging due to the involvement of multiple governmental agencies and municipalities.

Anticipating innovative technologies to improve interlinked transportation networks is being added to many connected streets designs. Intelligent transportation systems (ITS) are a growing planning method as Mobility as a Service (MaaS), and smart vehicle technologies merge with traditional transit operations. ITS challenges complete street designers to envision advanced multimodal transportation systems using automation and electric mobility options to improve the efficiency and sustainability of transportation networks.