Highway intersections need special attention when performing asphalt paving, as heavy; slow-moving vehicles stop, turn and accelerate in these areas; exposing intersections to some of the highest stress levels found in asphalt pavement. Climbing lanes, truck weigh stations, rest areas and other slow speed areas also expose asphalt pavement to high-stress conditions. These areas require special attention to ensure that high-stress areas deliver the same outstanding performance as other asphalt pavements.
To ensure excellent performance for intersections and other high-stress areas, engineers have designed a four-step system. The four steps of intersection paving are: 1. Assess the situation. 2. Ensure structural adequacy. 3. Select high-performance materials and confirm the mixture design. 4. Use proper construction techniques.
Assess the Situation. Engineers typically perform functional evaluations and structural evaluations. Functional evaluations take into consideration the surface characteristics of the road, types of cracking, surface smoothness, noise, and surface friction characteristics. Structural evaluations are used to determine the ability of the pavement structure to carry current and future traffic. This requires detailed information about pavement thickness, paving layer material properties, subgrade support conditions, traffic, and the response of the existing pavement to loading.
Ensure Structural Adequacy. An intersection must have adequate thickness to perform well and provide the structural strength to meet traffic needs. Thickness must account for normal factors such as subgrade strength, base thickness, and traffic. It is critical that the structural adequacy of the in-place material be evaluated when working with existing pavements. Failed or weak layers must be removed before beginning the paving process. Paving over failed material will most likely result in reoccurring failure.
Select High-Performance Materials and Confirm Mix Design. Engineers have the necessary tools for improving the performance of asphalt intersections and high-stress locations. A performance-graded (PG) binder system is used to select the proper type of liquid asphalt to bind the aggregate material together in the finished pavement. Selection is based on the area’s climate and loading conditions. Intersections, which experience stopped and slower traffic, require a stiffer binder.
Use Construction Techniques. The use of correct construction techniques is, without a doubt, critical to the quality of high-performance intersections. Three points that are worth mentioning here are: proper compaction, avoidance of segregation, and good joint construction. Proper compaction is important for long-term durability and reduces air and water intrusion, which could cause early aging to the pavement. Segregation occurs when different size particles in the aggregate separate during handling and placement, causing a weaker, more open-textured pavement. This type of pavement will be less durable. Joint construction techniques are important to prevent the intrusion of air and water at the construction joints.
Several studies have been conducted which proved that high-stress areas such as intersections required annual restoration. When following all the correct steps during asphalt pavement, these frequent maintenance jobs can be avoided. For more information about Crisdel’s capabilities, please view some of our award winning projects at: https://www.crisdel.com/projects