Roadways: Design and Maintenance for Motorcycle Safety

Roadway design is essential to the safety of all road users, but motorcyclists require specific considerations because they lack the physical protection available to passenger vehicle occupants. Engineering design for motorcycle safety is an aide in reducing crash incidents, reducing injury severity, and creating safer, more predictable travel conditions for riders.

Road-surface conditions are a critical motorcycle safety factor because motorcycles are particularly sensitive to pavement defects and abrupt changes in friction or elevation.  Roadway maintenance issues like potholes, cracking, surface irregularities, loose aggregate, and low-friction contaminants can adversely affect tire contact, steering control, and vehicle stability.  Accordingly, pavement systems should be designed, constructed, and maintained to provide a durable, uniform profile skid-resistant riding surface with effective surface drainage.  Drainage methods should limit ponding and sheet flow across travel lanes, especially on horizontal curves and at intersections where braking, turning, or changes in lean angle increase the consequences of traction loss.  The location of utility covers, bridge joints, patches, and other surface discontinuities should be evaluated during design and maintained to minimize differential elevations and variations in skid resistance within the anticipated motorcycle wheel path.

Roadway geometric design is also an important consideration for motorcycle rider safety. Horizontal and vertical alignments should provide decision sight distance appropriate to the roadway context, consistent curvature, properly developed superelevation, and clear delineation that enables riders to anticipate changes in alignment.  Sudden reductions in curve radius, inadequate transition lengths, or inconsistent cross slopes can increase the potential for lane departure and loss of control.  Regulatory and warning signs, pavement markings, chevrons, and other delineation devices should provide timely, unambiguous information regarding advisory speed, alignment, and changing roadway conditions.  Where practicable, fixed objects—including utility poles, trees, and drainage appurtenances—should be located beyond the applicable clear zone; where removal or relocation is infeasible, appropriate crashworthy shielding should be considered in accordance with governing design criteria.

Intersections require special attention because they are common locations for motorcycle crashes.  Engineers can enhance intersection safety by providing adequate sight distance, clear lane-use markings, appropriate signal phasing, and when reasonably possible illumination.  Traffic-calming treatments should incorporate motorcycle-compatible geometry so features like speed humps and raised crossings should avoid abrupt elevation changes or friction variances.  Auxiliary turn lanes and channelization should provide width and storage for rider positioning and maneuvering.

Pavement markings and traffic signage must be maintained to remain effectively visible during wet-weather and nighttime conditions.  Additionally, it is important that the construction/maintenance specification of pavement marking materials and installation account for motorcycle stability.  Surface markings should provide skid resistant properties that minimize differential friction between the roadway pavement and the painted marking, particularly along horizontal curves, within intersections, and in areas known to experience frequent braking or turning maneuvers.

Lastly, roadway safety should be supported by regular inspection and timely maintenance.  Gravel, oil, construction debris, damaged pavement, vegetation, and poorly maintained signs can create significant hazards for motorcyclists.  Roadway hazards should be responded to promptly and maintenance or roadway improvement schedules should consider motorcycle historical crash data.

In conclusion, motorcycle safety should be integrated into roadway design from the planning phase through construction and incorporated into inspection programs and planned maintenance.  It is important to understand that hazards to motorcycle riders can be reduced by the following:  adequate visibility, reasonably safe geometry, a uniform abrasive pavement surface, designing safe intersections, the effective placement of signs and markings, and a consistent inspection/maintenance program.  Designing roadways should include a focus on motorcycle safety, which not only benefits motorcycle riders but also the overall safety and reliability of the transportation system.

Whether you represent a plaintiff or defendant, these engineering practices for motorcycle safety should be part of your investigation.  If you are handling a matter involving a motorcycle accident CESI can help.