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Our transportation network is a regional system. It consists of streets, sidewalks, light rail lines, bicycle lanes, and all other infrastructure that is in place to support the movement of people and goods. The focus of this project is our streets and how to think differently about their development. This cannot be done, though, without also considering the broader transportation network of which our streets are a part.

Functional class table
Source: East-West Gateway

From a purely vehicular perspective, there is a hierarchy of streets in our transportation system. Traditionally, the roadway functional classification system has been used to describe how travel flows through this hierarchy. East-West Gateway, the metropolitan planning organization (MPO) and council of governments (COG) for St. Louis, is responsible for maintaining and updating the region’s functional classification system. The table at right depicts the current regional classification system.

The table above is based primarily on vehicular travel. Great streets, though, are more than just conduits for vehicular traffic.

They are public places woven through the social and economic fabric of our communities. In this context, the street network is much bigger than the travel lanes that carry automobile traffic through our region. It is a complex system of dynamic components that dramatically affects the quality of our public spaces. If our street network is only a conduit for automobiles, then we are failiing to maximize the massive investment of public revenue into our transportation infrastructure. This principle is at the core of great street planning and design.

Great streets must be "complete". They must move vehicular traffic, yes; but that is only one of many important roles that they can and should have. They should provide access to all users, regardless of economic status or disability. They should stimulate economic growth. They should offer multiple, attractive modes of travel from which to choose. They should provide attractive places for the congregation of local residents and visitiors. For streets to be great, these factors and many others must be considered as we choose how to allocate space along our thoroughfares.

Cross section of street
Credit: CAI

Space Allocation is a Choice. Historically, the automobile has dominated space along most of our thoroughfares. Growing populations with growing numbers of personal automobiles-per-household have caused us to choose thoroughfares that are good for little else than the movement of vehicular traffic. To make matters worse, when congestion rises along these thoroughfares we have typically chosen to add vehicular capacity by widening the travel way. The result of these choices is a network of thoroughfares that is predominantly unfriendly to pedestrians, transit, and bicyclists. It has also negatively affected land uses along our thoroughfares.

If we want to create great streets in place of these auto-dominated roadways, we must think differently about space allocation along the thoroughfare. Space allocation is a choice, and our choices have consequences. Choosing to prioritize vehicular traffic will often have negative consequences for other modes and abutting land uses. Choosing to prioritize other modes is a healthy part of great street development, but it may negatively impact vehicular mobility along the thoroughfare. This is where the street network is an extremely important consideration in great street planning and design. Choices that may constrain vehicular travel, such as road diets, lower speeds, raised medians, etc., can be offset if the surrounding street network is effectively utilized.

Road diets must consider network context. All of the streets within the regional system work together to provide mobility and access throughout the metropolitan area. Every street serves a specific function within the regional network. This is an important point to remember during the planning phases of great street development. If road diets are considered, the following questions should be addressed in evaluating its merits:

  • Does the existing road serve a major mobility function in the region?
  • If so, are their parallel streets nearby to help serve potential excess traffic demand?
  • If the parallel street system is severed/discontinuous, could improvements to the local road network mend those gaps to provide alternative route choices for excess traffic demand?
  • Is there a desire/opportunity to promote transit along the thoroughfare in order to serve excess traffic demand?
  • Is there a desire to provide good bicycle accommodations?

Grids are important for great streets. Regardless of whether a road diet is part of a great street development, the street network surrounding the respective thoroughfare is an important component to consider in the decision making process. At the dawn of the street system in America, urban areas typically developed in a "grid pattern". Over time, suburban sprawl led to non-grid development patterns in many areas, resulting in disconnected networks that rely upon select major arterial streets for the vast majority of vehicular mobility.

Transforming these thoroughfares into great streets is a complex challenge, and it is further complicated by the lack of grid network surrounding the respective corridor. If great streets are desired in such locations, be sure to examine the surrounding street network for opportunities to improve connectivity. Sometimes it may be as simple as opening a cul-de-sac to connect with a nearby street. In other cases, more substantial links may be required; but the increased network capacity can allow us to think differently about space allocation along the thoroughfare in question. It may suddenly be reasonable to reduce vehicular capacity along the thoroughfare if network capacity can be improved through enhanced connectivity. A reduction in vehicular capacity along the thoroughfare gives us more freedom in how we choose to allocate space and prioritize other modes.