A Systematic Approach to Applying Seasonal Load Restrictions

Weigh-in-Motion sensors and environmental and structural instruments are being used by many state departments of transportation not only to monitor traffic, but also to evaluate the effect of different factors including traffic, temperature and strain on the life of pavement. A significant amount of information on instrumented test sections is available from test sites such as MNRoad, VA Smart road and NCAT, which continue to provide valuable information regarding different aspects of pavement design and performance. All pavement sections, however, are traversed by unique combinations of traffic during distinct temperature conditions. While general conclusions from an instrumented asphalt pavement test section in one state are applicable to other states, the unique combinations of temperature and traffic in any state call for state-specific data, such as seasonal load restrictions, when making policy decisions which impact the life of pavement, such as seasonal load restrictions. Many miles of low to medium volume roads in the state of Maine are traversed by heavy trucks, a large percentage of which transport logs for the forest product/paper industry, and these trucks have unique combinations of axle/wheels and trailers that are not commonly found in other states. Additionally, Maine experiences a pronounced fluctuation of temperature throughout the year. This study gathered traffic, environmental and pavement strain data on a section of Route 15 in Guilford, Maine with the following objectives: 1. To determine the traffic type and load distribution across different months; 2. To develop a model to predict pavement temperature at the location of critical strains; 3. To evaluate the effect of temperature on tensile strain in an asphalt pavement layer; 4. To develop a policy for placing and lifting the State of Maine’s seasonal load restrictions. This paper presents a sample of the data gathered, the analysis method employed, and suggests a systematic approach to using the data to determine appropriate times for placing and lifting of seasonal load restrictions based on environmental conditions, to minimize damage to the pavement and maximize pavement life. Since the data and observed performance can also be used to estimate the contribution of traffic in different seasons toward the damage of the pavement, both can be used to approximate the life expectancy of a pavement through rational means.