Road Design
12. Reducing Number of Lanes

Many roads have more travel lanes than necessary. Reducing the number of lanes on a multi-lane roadway can reduce crossing distances for pedestrians and slow vehicle speeds. A traffic analysis should be done to determine if the number of lanes of roadways - many of which were built without such an analysis - is appropriate. Level of service analysis for intersections should not dictate the design for the entire length of a roadway. For example, a four lane undivided road can be converted to one through lane in each direction with a center left turn lane or with a raised median and turn pockets and bicycle lanes on both sides of the roadway. Turning pockets may be needed only in specific locations.

Depending on conditions, it may also be possible to add on-street parking while allowing for bicycle lanes on both sides of the street - instead of a center turn lane. If no sidewalks exist on the roadway, these should be added. If sidewalks exist, and there is adequate room, a landscaped buffer is desirable to separate pedestrians from the travel lane.

A typical three-lane configuration (two travel lanes and a center turn lane) has advantages for motorists also: through traffic can maintain a fairly constant speed, while left-turning drivers can enter the center turn lane to wait, out of moving traffic.

 

 

 

 

Purpose:

  • Remedy a situation where there is excess capacity.
  • Provide space for pedestrians, cyclists and parkers.
  • Reduce crossing width and help optimize signal timing.

Considerations:

  • A traffic analysis should segregate intersection capacity needs from through capacity needs to determine overall design.
  • Select routes with minimal out-of-direction travel, and less need to walk along a busy street.
  • Ensure street connections so major arterials can be crossed at controlled intersections
  • Cluster development in nodes that are accessible to transit.

Estimated cost

The cost for restriping a mile of four-lane street to one lane in each direction plus a two-way left-turn lane and bike lanes is about $5,000–$20,000 per mile, depending on the amount of removing and repainting lane lines required. The estimated cost of extending side-walks or building a raised median is much higher and can cost $100,000 per mile or more.

If a reconfiguration is done after repaving or overlay for maintenance, and no curbs are changed, there is no cost for the  change.