Rules of Thumb for Urban Intersection Design

In many rural places around the country, an intersection consists of either a stop sign or the constant blinking traffic light in the middle of town.  Usually, no one even pays attention to rules such as yielding to another car or knowing who has the right of way.  People cross the street at random places while waving to you in your car.  You might even see a tractor drive past you.

In urban settings, however, an intersection is sometimes a major source of chaos.  In New York City, for example, some intersections have multiple signs consisting of parking, walking, standing, bicycle, and pedestrian rules, it’s not a surprise that many car crashes happen at intersections.

Also, how many drivers even know the rules of the road?  Who has the right of way?  Where can cyclists ride?  Where can pedestrians cross?  Instead of piling on the road signs, intersections should be designed so that they convey safety for both drivers and pedestrians without a cluster of confusing signs.

Below is a list of general “rules of thumb” to keep in mind when designing an urban intersection:

  • Design the intersection to be self-evident to all users
  • Make the intersection as small as possible
  • Align lanes so that the number of approach and departure lanes are equal
  • Square off skewed intersections
  • Manage driver speed, especially turning speed
  • Limit opportunities for drivers to make sudden movements
  • Minimize crossing distances
  • Locate crossings along desire lines
  • Locate crossings and waiting areas within sight triangles
  • Organize bus stops to minimize transfer distances
  • Merge cyclists with slow speeds and low volumes, separate cyclists from fast speeds and high volumes
  • Prioritize cyclists over turning drivers
  • Ensure sufficient queue space for cyclists
  • Utilize predictable/natural signal phasing
  • Minimize delay for all modes
  • Prioritize signals for pedestrians, cyclists and transit
  • Ensure that signal timing works for both commuters and slower walkers
  • Convert non-driving or cycling space to sidewalk or island
  • Landscape or use sustainable materials for all spaces not used for walking, cycling, or driving

These rules of thumb are from the ITE Journal article Real Urban Intersection Design by King and Chellman, which cites the NATCO Urban Street Design Guide.

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