Whether driving, shopping, walking or lingering, intersections are a focal point of activity and decision, and thus are critical parts of the city streetscape and transportation network. Intersections account for the most serious conflicts between pedestrians, bicyclists, and drivers, but also present opportunities to reduce crashes when designed carefully. Good intersection design can tap civic and economic potential, infusing overbuilt or underutilized spaces with street life.
Intersection design should facilitate visibility and predictability for all users, creating an environment in which complex movements feel safe, easy, and intuitive.
Their design should promote eye contact between all street users, engendering a streetscape in which pedestrians, drivers, and bicyclists are aware of one another and can effectively share space. Intersections are the most challenging aspect of street design in an urban environment. Capacity constraints at these pinch points in the roadway network govern the width of roadways as they pass through them. People on foot may avoid difficult crossings or subject themselves or their children to considerable risks while crossing a street at a poorly designed intersection. The principles outlined here enable practitioners to build intersections as meeting points that function well for everyone using them.
Design Intersections to be as Compact as Possible
Compact intersections reduce pedes- trian exposure, slow traffic near conflict points, and increase visibility for all users. Limit the addition of dedicated turn lanes and pockets, and remove slip lanes where possible. Break large, complex intersections into a series of smaller intersections. Use existing pedestrian behaviors and desire lines to dictate design.
Analyze Intersections as Part of a Network, not in Isolation
Solutions may be found at the corridor or network level. Trade-offs can often be made between the intersection and the network in terms of traffic volume and capacity.
Integrate Time and Space
Reconfiguring intersections in time (through signalization) provides an alternative to widening intersections to solve delay or congestion. Integrate spatial and temporal intersection design strategies throughout a project.
See Traffic Signals
Intersections are Shared Spaces
The goal of intersection design is not strictly to reduce the number of conflicts for a given user at a select location, but to create a space in which users are mutually aware of one another and visible and predic- table in their actions to reduce the overall rate and severity of crashes.
Utilize Excess Space as Public Space
Interim public plazas and low-cost safety improvements should be used to enhance public life and mitigate safety concerns in the near-term.
Design for the Future
Design should account for existing and future land uses as well as projected and induced demand for all users. Land uses and pedestrian generators play an equally important role in making decisions about intersections and relate directly to the desires and objectives of the surrounding community.
See Design Year
Adapted from the Urban Street Design Guide, published by Island Press.