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CONVERTING PAVED ROADS TO UNPAVED The purpose of this study was to identify agencies that have converted roads from paved to unpaved. The study also identified â¢ tools, metrics, and procedures that have been used in the decision-making process for when and how to convert a road; â¢ impacts of road conversions; â¢ public outreach efforts; and â¢ knowledge gaps and research needs. The survey conducted for this project identified 48 local, state, and federal agencies that have conducted road conversions and nine more that are considering this action. Almost 70 conver- sion projects were identified and a total of 550 miles of road converted to unpaved. Low-volume, rural roads serve as main routes for numerous industries, farmers, and ranchers to get raw material from source to distribution or processing centers, provide ingress to remote public lands, and act as transportation arteries for millions of rural residents. Most of these rural roads have low or very low traffic volumes and have unpaved, aggregate surfaces. Historically, unpaved roads have been considered the lowest level of service provided. In a demonstration of progress and an effort to improve road conditions for rural residents, many agencies paved low-volume roads with little or no base preparation when asphalt and construc- tion prices were low. Those asphalt roads have now aged well beyond their design service life, are rapidly deteriorating, and are difficult and expensive to maintain. The increasing sizes of agricultural and commercial equipment, including that used by the energy sector, are compounding road deterioration in many areas. Traditionally, these roads were maintained or repaved at regular intervals, but with the increasing traffic loads, increas- ing cost of materials, and stagnant or declining road maintenance budgets, many agencies do not have the funding to support these activities. Instead, many local road agencies are look- ing to convert deteriorated paved roads to unpaved ones as a more sustainable solution. The practice of converting roads from paved to unpaved is relatively widespread. Documented cases of road conversion projects were found in 27 states. The state of the practice for converting roads from paved to unpaved involves reclaim- ing or recycling the deteriorated pavement surface, supplementing existing materials as needed, compacting, and for some applying or incorporating a surface treatment, such as a soil stabilizer or dust-abatement product. In a few cases, no recycling of the old pavement was done, and new surface aggregate was simply placed over the deteriorated road surface. However, most agencies that have done conversions recycle the old surface in-place and reshape and compact it as a base for a new aggregate surfacing. Thereafter, the new sur- facing ranges from locally available gravel to high-quality surface aggregate that can be maintained with motor graders to sustain adequate crown and a smooth surface. Many of the roads that have been converted from paved to unpaved had annual average daily traffic (AADT) of between 21 and 100 vehicles, suggesting that many of the roads that are being SUMMARY
2 converted should not have been paved initially or that road usage patterns have changed significantly since paving. Local road agencies are converting roads primarily as a result of a lack of funding for maintenance and construction, safety issues, and/or complaints from the public. Road bud- gets have remained stagnant or declined in recent decades, but the costs of labor, materials, and equipment have continued to increase. Consequently, local road agencies have been left underfunded and are struggling to maintain their existing road network. Limited maintenance of deteriorating roads (e.g., pothole patching) often is all that can be done with existing resources, with repaving often being cost-prohibitive. In seeking a cost-effective alternative to continued maintenance and repair of deteriorating pavement, agencies have begun to recognize that many roads with very low traffic volumes can be maintained more economically and at a higher level of service with an unpaved or granular surface. Local road agencies have experienced positive outcomes by converting roads. Many local road agencies reported cost savings after converting, compared with the costs of continuing maintenance of the deteriorating paved road or repaving. The reported cost of converting ranged from $1,000 to $100,000 per road segment or mile within the United States and Canada. The variation in costs is attributed to how costs are tracked by agencies, how the conversion was done, equipment requirements, supplemental materials, surface stabilization and dust abatement, and addressing drainage and road base issues. A significant lack of available resources, such as a handbook or design guide, for practi- tioners who are considering or performing road conversions was noted. Numerous survey respondents indicated that they did not use any documented resources when planning and per- forming the conversion and often used a trial-and-error approach. In addition, road agencies rarely document procedures and outcomes of road conversions, such as construction prob- lems, crash rates, public concerns and reaction, and comparative maintenance costs of the new surface. Completing successful conversions is possible with appropriate investigation and design, selection of quality granular surfacing materials, and good construction, and by involving and educating the public as part of the process. However, limited information has been published to guide practitioners in these processes. Conversion is a viable option that can be accomplished in a positive way for all stakeholders provided that the public is involved in the discussion and appropriate designs and procedures are followed. To accomplish this, local road agencies would benefit from direction in planning projects that will lead to the optimal use of available materials and equipment and a smooth, safe, and maintainable driving surface upon completion. This can be accomplished with development of guidance materials and improved technology transfer to practitioners. Road agencies that conducted public outreach and stakeholder education about various aspects of the conversion process observed more favorable public reaction than did those who did not involve the public. Other techniques that can be used to improve the overall results of a project include treating or stabilizing granular surfaces to control dust, limiting the rate of aggregate loss, and reducing the frequency of motor grader or blade maintenance. Stabiliza- tion procedures also can improve safety, increase public acceptance, and reduce life-cycle costs and environmental impacts after a conversion has taken place. Knowledge gaps identified point to the need for future research leading to: â¢ Design guidance on converting roads from paved to unpaved for use by practitioners and road agencies; â¢ Improved documentation of the results of conversions, procedures, and mechanisms for collecting crash rates and data on low-volume roads, specifically before and after conversions;
3 â¢ A life-cycle cost analysis tool for determining whether conversion is a cost-effective solution; â¢ A road management framework for local road agencies that are affected by industries that use heavy-weight vehicles or that significantly increase the numbers of vehicles using the road, and that seek to recoup costs associated with accelerated road deterioration caused by such vehicles; and â¢ Assessment of environmental impacts associated with road conversions.