Development of Unpaved Road Performance Models to Determine the Cost-Effectiveness of using Chemical Treatments to Reduce Gravel Loss and Maintenance
I. Research Problem Statement Local government, county and private agencies around the US invest millions of dollars on unpaved road upgrades, stabilization and maintenance on a yearly basis. These roads are critical to agriculture, natural resource management, oil and mineral extraction, and access to rural communities. Despite often meager maintenance budgets, many of the secondary unpaved road networks receive annual chemical treatments with the belief that these treatments, in addition to controlling dust, will reduce the rate of gravel loss and the number of times that the road needs to be bladed each year. The costs associated with these activities in many rural communities in the US consume a substantial percentage of their total budgets. The cost-effectiveness of annual dust control and stabilization treatments depends on many variables such as application rate and method, climate, aggregate properties (gradation and plasticity), traffic volume, type and speed, maintenance practices and frequency and future resurfacing costs. Life-Cycle Cost Analysis (LCCA) principals can be used to measure the realistic cost/benefit of different road investments, maintenance and management scenarios over time (e.g., period of 10 years), provided that accurate input data is used. There is currently only limited long-term (multi-year) performance data available that quantifies savings in terms of reduced gravel loss and maintenance when unpaved road chemical treatments are used. This research project would monitor the performance and cost of different unpaved road chemical treatment scenarios and maintenance regimes against untreated controls over several years. Gravel loss, road performance, maintenance requirements, vehicle operating costs, and optimal product rejuvenation intervals would be documented, and performance prediction models developed.
II. Research Objective:
The main objectives of this research project are to determine the impact of annual chemical treatments on aggregate deterioration trends, and to develop cost-effective annual dust control treatment programs to prolong aggregate life. The main outcomes of this project will be the following: • Aggregate deterioration trends for treated and untreated aggregate surfaces • Performance of different treatments and maintenance regimes • Cost/benefit analyses of different treatments • Performance prediction models for different treatments
III. Potential Benefits
Meeting the proposed objectives will provide road agencies tasked with managing unpaved roads a set of tools to make informed decisions about the use of chemical treatments. Appropriate use of these treatments will result in safer roads, improved quality of life, extended gravel replacement intervals, and reduced maintenance interventions. The economic, social, and environmental benefits will be significant if the savings extend across the entire US unpaved road network.
IV. RELATIONSHIPS TO THE EXISTING BODY OF KNOWLEDGE
Only limited published scientific research has been conducted to support the theory that chemical treatments can be cost-effectively used as part of an unpaved road management strategy to reduce gravel loss and maintenance. Existing aggregate deterioration models for untreated surfaces, usually developed in developing countries, do not consider chemical treatments and have other limitations in North America in terms of materials and traffic. These models need to be validated and supplemented with algorithms that consider the use of chemical treatments and compare the costs and benefits of these treatments against not treating the road. Two studies identified are as follows: • Mahgoub, H., Skorseth, K., O’Neill, M., and Maharjan, P. 2011. Gravel Loss Model Evaluation. The Transportation Research Board 90th Annual Meeting. TRB, Washington, D.C. • RTAC. 1987. Guidelines for Cost Effective Use and Application of Dust Palliatives. Roads and Transportation Association of Canada (RTAC). Ottawa, ON. 87 p.
V. FOLLOW-ON AND IMPLEMENTATION ACTIVITIES
There are a number of initiatives underway in the United States to improve the way that unpaved roads are managed. The Federal Highway Administration is currently funding the development of tools that guide practitioners on selecting appropriate chemical treatments for a given set of conditions. Four universities have established the Road Dust Management Institute, which will serve as a resource for technology transfer and training on unpaved road management. This proposed project is part of this initiative to formalize the use of chemical treatments. Follow-on research will include the development of customized performance and environmental testing methods specific to unpaved roads and chemical treatments used on them, the development of generic specifications for the different types of road additive, and the refinement of performance prediction models as new types of chemical treatment become available. It is anticipated that the Federal Highway Administration, Federal Lands Highway Division, will take ownership of the planned deliverables.
VI. ESTIMATED FUNDING REQUIREMENTS
The estimated cost will be about $450,000 over a three year period.