Bicycle Safety Guide and Countermeasure Selection System


Example of a wide outside lane. - Libby Thomas - Austin Brown Example of a wide outside lane. - Austin Brown




Wide Curb Lanes

A wide curb lane (WCL) is the lane nearest the curb that is wider than a standard lane and provides extra space so that the lane may be shared by motor vehicles and bicycles. These facilities can also be placed on roads without curbs and are sometimes called wide outside lanes. Wide curb lanes may be present on two-lane or multilane roads. A desirable width is 14 feet, not including the gutter pan area. Lanes wider than 14 feet sometimes result in the operation of two motor vehicles side by side. However, the WCL may need to be 15 feet wide on sections with steep grades or where drainage grates, wide gutter pans, raised reflectors, or on-street parking reduce the usable lane width. Wide curb lanes are sometimes designated when right-of-way constraints preclude the installation of "full width" bike lanes. WCLs are sometimes put in place by re-striping and narrowing the other travel lanes on multilane roadways, especially when a section of roadway is resurfaced.

Wide curb lane advocates believe that these wider lanes encourage bicyclists to operate more like motor vehicles and thus lead to more correct positioning at intersections, particularly for left-turning maneuvers. A previous FHWA publication recommends WCLs in many kinds of roadway situations where most bicyclists are experienced riders. The 2012 AASHTO Guide for the Development of Bicycle Facilities discusses WCLs, but suggests that bike lanes or shoulders are the preferred facility type on major roadways when sufficient width is available. The Guide also discusses the use of signs and pavement markings on WCLs.


Wide curb lanes create on-street travel facilities for more experienced and confident bicyclists through marking lanes wide enough so that motor vehicles and bicycles have adequate room to share the lane during overtaking.


  • Where WCLs are to be considered, the road or street should be evaluated to determine if this facility is appropriate. The provision of WCLs should be weighed against the likelihood that motorists will travel faster in them and that heavy vehicles (where present) will prefer them to inside lanes, resulting in decreased level of service (i.e., perceived safety and comfort) for bicyclists and pedestrians.
  • Provide appropriate WCL width, especially where drainage grates/gutters or other factors reduce the usable lane width or conditions such as steep grades require greater operating space for bicyclists.
  • Consider the use of shared lane markings (sharrows) on roadways with posted speed s of 35 mi/h or less to help with proper bicyclist placement within the WCL and to indicate to motorists where to expect bicyclists in the lane.
  • Truck traffic should not exceed five percent of the total motor vehicle traffic.
  • The costs and benefits of constructing new roadways with WCLs should be carefully weighed. Bicycle facilities such as bike lanes that attract a broader range of users may be added to a new roadway for a similar, or marginally higher, cost.

Estimated Cost

Normally, the only cost associated with WCLs is for re-striping the roadway. It is most cost efficient to create WCLs during street reconstruction, street resurfacing, or at the time of original construction.

Safety Effects

A summary of studies that have looked at the safety effects of wide cub lanes can be found here.


To view references for this countermeasure group click here.

Case Studies