Signed/Marked Shared Lanes

Description

A wide outside lane in Chapel Hill, North Carolina

All roadways, except where prohibited by law, are shared by bicycles and motor vehicles. Roadways that carry low traffic volumes, such as neighborhood streets or rural roads, often provide a comfortable bicycling experience. On major roadways, wide curb or outside lanes could be used to provide more space for motorists passing bicyclists, or for bicyclists to maneuver around obstacles like drainage grates or on-street parking. Signs that say SHARE THE ROAD or BICYCLES MAY USE FULL LANE help alert motorists that they may encounter bicyclists and encourage them to be respectful.

A shared-lane marking in Asheville, North Carolina

A shared-lane pavement marking can also be used to provide a higher level of guidance to bicyclists and motorists. The placement helps bicyclists visualize the appropriate lateral position, especially when it comes to avoiding the open door of a parked vehicle or when the lanes are too narrow for bicyclists and motorists to travel side-by-side. These markings can also be used to fill in the gap between two sections of a roadway with bike lanes. The MUTCD provides guidance about the placement of shared-lane markings.

Purpose

Signs help alert motorists to the presence of bicycles, while markings alert motorists and offer guidance to bicyclists.

Considerations

  • Various geometric and operational factors affect the comfort level of bicyclists using shared lanes.
  • Use appropriate signal timing and detector systems that respond to bicycles.
  • When designing a wide outside lane, the gutter should not be included in the lane measurement as usable width.
  • Long-term maintenance costs should be taken into consideration as durability and cost are generally inversely related.
  • Bicyclists will need more space on sections of roadway with steep grades, drainage grates, or on-street parking.
  • Shared-lane markings may be more appropriate, compared to striped bike lanes, on steep downgrades where bikes might be traveling at higher speeds adjacent to parked vehicles.

Cost

Shared-lane costs vary depending on what additions are made to the roadway. Signs can be added for approximately $300 each, and shared-lane markings for approximately $180 each. More substantially, developing a signed bicycle route can range from approximately $5,000 to $65,000 per mile. More detailed cost information is provided here.