Road Diets in Hampton Roads

By Robert B. Case, PE, PhD

February 20, 2018

Some roads are wider than needed for the amount of autos using them.  A “road diet” converts a road into a street, i.e. facilitates accessing houses and shops along the segment, a) by reducing the number of lanes which one must cross to turn left into a driveway, and b) by using the pavement of the surplus travel lanes for a two-way left-turn lane between travel lanes, on-street parking, and/or bike lanes.

To help local cities find roads to investigate for a possible road diet, HRTPO staff:

• investigated the pros and cons of road diets to determine those situations in which road diets may be desirable, and
• prepared a database and maps providing information on those criteria for existing 4-lane undivided segments with suitable (low) traffic volumes in Hampton Roads. 

Although results vary by measure of effectiveness, road diets—if implemented on roads with less than 15,000 vehicles per day (vpd)—typically have good results:

• safety
  • typically a 50% decrease in auto crashes

• vehicle running speeds
  • typically reduce vehicle running speeds by a few miles per hour, and reduce the amount of excessive speeding

• intersection delay
  • the road diets with a significant increase in delay had approximately 15,000 vpd, indicating the danger of road diets on roadways with 15k+ volume

• bicycle usage
  • an increase of approximately 30% in bicycle volume can be expected when implementing a road diet with bike lanes

• walking
  • given the scarcity of pedestrian data for road diets, it is currently not possible to know the impact of road diets on walking, but lower auto speeds and fewer lanes to cross benefit pedestrians

• bus ridership
  • based on the scarcity of data, the impact of typical road diets on transit usage is unclear, but bus riders usually walk to begin/finish their trips

• auto volume
  • the excessive intersection delay of road diets implemented on roads with more than 15,000 vpd causes a reduction in auto volumes 

Therefore, a road diet is desirable:

• for segments with a high crash rate, or
• for segments along which localities wish to accommodate cycling, bus transit, and walking (e.g. gaps in alt-transportation network, low-income areas, etc.), or
• for “roads” which localities wish to convert to “streets” to improve access to street-oriented land uses (e.g. townhouses, apartments, and shops on street)

Consequently, to help localities find locations to investigate for a possible road diet, staff prepared 1) a database, 2) maps, and 3) observations concerning the above issues for existing 4-lane undivided segments with less than 12,500 vpd.

Find an example map and observations below:

Bainbridge Blvd, from Poindexter St to Post Ave

Source: HRTPO staff ESRI mapping using crashes and volumes (VDOT), cross-section (Google Maps), commuting (Census)

Bainbridge Blvd, from Poindexter St to Post Ave

• low crash rate (3 per million vehicle miles traveled (VMT)
• bike/ped facility on nearby Jordan Bridge
• some alternative transportation commuters living nearby
• existing bus route
• existing residential street-oriented land use (existing small residential lots), existing commercial street-oriented land use (existing businesses on street), and potential for more street-oriented land use (some vacant land)

To see draft study—and to provide comments—go to Public Comment Opportunities.