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In this article, Civil Engineer Thomas Lyden and Automotive Engineer Roland Hoover provide an overview of pavement crack sealing and discuss how misapplications of sealant can contribute to motorcycle and bicycle crashes.
Sealing roadway surface cracks with tar and other sealant materials is a common maintenance practice intended to prevent water intrusion and further pavement degradation. However, if not properly performed, this practice can negatively affect roadway friction and create surface irregularities; both of which can contribute to the cause of motorcycle and bicycle crashes.
Hazards to Motorcyclists & Bicyclists
Roadway repairs to address pavement degradation, surface cracks, and irregularities have the potential to negatively affect vehicle control and must be performed in a manner that considers the driving dynamics of all road-going vehicles, including motorcycles and bicycles. Crack sealing activities are no exception, and the transportation and construction industries are well aware of the associated hazards .
The materials used for crack sealing tend to be very slick when wet or oily. A reduction in the coefficient of friction between the roadway surface and the tire contact patch can be especially dangerous for 2 wheeled vehicles. With the contact patch of a motorcycle at about the size of a tennis ball and a bicycle’s as small as a dime, these vehicles are frequently operated with the entirety of their tire contact patch upon roadway repairs. Unlike passenger cars and trucks which distribute their weight across four tires in total, and at least two at each axle, and are generally unaffected by the loss of traction in a single tire, the stability of balanced vehicles is significantly compromised where either tire encounters slick conditions.
Beyond slick conditions, road repairs that cause a bump or ridge in the direction of travel can lead to an unintended steering effect or a lack of steering response, creating a loss of directional control.
Frictional changes or unintentional direction changes while riding a motorcycle or bicycle are the cause of many single vehicle crashes.
Proper Application of Crack Sealant
Crack sealing is not an appropriate solution for all surface defects and must only be applied to pavement distresses which will benefit from its timely application. As previously noted, the misapplication of sealant is not only wasteful; it has the potential to create hazardous surface conditions.
Issues to Watch For in Crack Sealing Cases
Guidelines for Safe Crack Sealing
In order to improve safety, there are a number of standards and industry practices guiding the use of crack sealant.
Road maintenance personnel must be trained on motorcycle and bicycle safety issues with any maintenance practice, but especially crack sealing operations.
The highway experts at Robson Forensic examine crash sites, use field measurements, scrutinize crash scene photos, and review infrastructure design documents to determine if highway factors or road conditions contributed to the cause of motor vehicle crashes.
The specific actions of a bicyclist within the context of an incident will often be evaluated by a specially qualified bicycle expert. For more information on bicycle experts at Robson Forensic, please visit our Bicycle Forensics page.
For more information contact the authors of this article or submit an inquiry through our website.
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