Bicyclists are particularly vulnerable to sudden changes in the roadway (or path) surface, such as potholes or sudden drop-offs. Slippery surfaces, presence of water or debris, broken pavement, and gaps in pavement parallel to the roadway that can trap bicycle tires can also be hazardous. In addition to causing bicyclist falls, surface irregularities may contribute to a sudden weaving movement that may place the cyclist in the path of a motorist. Poor riding surfaces may also increase bicyclist discomfort and potentially discourage riding. Therefore, providing smooth but non-slippery pavement surfaces is a key to maintaining a good level of service for bicyclists. Good initial design can help reduce future repair and maintenance costs.
Several overarching issues warrant particular attention.
- Initial design and materials selection help to prevent problems such as poor drainage, slippery surfaces, gaps in pavement and others. Once design standards are determined, inspectors and project contractors should ensure that standards are met.
- Having a plan for regular sweeping and identifying and making spot repairs is key to keeping surfaces in good condition.
- Bicyclist considerations should also be incorporated into long-term maintenance and upgrades.
- Good design, hazard identification and maintenance practices should be institutionalized. Identification of bicyclist priorities and a system for regular inclusion of best bicyclist facilities practices within a regular maintenance framework can help to improve conditions for bicyclists without substantially increasing costs.
To provide smooth, level surfaces, the following are some potential hazards that may be minimized by instituting good design and maintenance practices. Drain grates should be maintained level with the surrounding pavement, which may require raising the grates following re-paving, and a bicycle-friendly design should be used so that tires will not be trapped by slots parallel to the roadway (see images). Particularly with new or reconstruction, curb inlets could be installed. Designs should also ensure that utility covers and other potential hazards are placed out of the predominant bicycling pathways, are level with the surrounding pavement, and have non-skid surfaces. Pavement should be kept in good condition, particularly near the edges where bicyclists tend to ride most often.
Additionally, when designing bike facilities, pavement seams should be placed where they minimally conflict with the bicycle right-of-way. Excessively wide gutter pans may unnecessarily reduce bicyclists' space. Paving over the gutter pan is a temporary solution, as seams usually reappear in the pavement within five years. Reflective raised pavement markers also create hazards for bicyclists and should only be used with appropriate consideration of bicyclists. These can deflect a bicycle wheel, causing the cyclist to lose control.
When rumble strips are used as a motorist alert, for example, along a shoulder, a narrower design placed close to the lane edge line allows more usable bicycle-friendly space. If textured pavers are used, these should not compromise bicyclist safety or comfort.
Finally, care must be taken to provide bicycle-safe railroad crossings. Crossings should ideally be close to 90 degrees. If the crossing is smooth, but non-slippery (concrete paving may work best), and the flange opening is kept as narrow as possible, somewhat more flexibility with the angle may be possible.
The Oregon Bicycle and Pedestrian Plan contains more information and illustrations of good surface design practices under the "Other Design Considerations" section (http://www.oregon.gov/ODOT/HWY/BIKEPED/docs/bp_plan_2_ii.pdf ).1
Many of the costs associated with providing and maintaining good bicyclist surfaces should be incorporated into the overall initial project budget or maintenance plan. The costs of hazard identification, short-term sweeping and spot maintenance programs will be minimized if bicyclist concerns are institutionalized within the regular maintenance and repair framework. Special repairs (such as drain grate repair/replacement) will vary considerably by project.