はじめに

スパイクタイヤの摩耗による発情は、アメリカ太平洋北西部では深刻な問題となっており、オレゴン、ワシントン、アラスカでは、アスファルト道路とポルトランドセメントコンクリート道路の両方に毎年数百万ドルの損害が発生しています。 アラスカ大学アンカレッジ校の研究によると、「2019年までに、今後20年間にアラスカで発生するスパイクタイヤ使用による道路被害の軽減対策にかかる総費用は、2億3200万ドルに上る」と推定されています。

挑戦

In Anchorage, Alaska, the studded tire rutting issues are especially prevalent due to high traffic. According to Drew Pavey, State Pavement Management Engineer for the Alaska Department of Transportation & Public Facilities (DOT&PF), “In some areas, we are seeing average wear rates of an eighth-inch (3 mm) a year.”

決議

Attempting to mitigate the studded tire damage, the Alaska DOT&PF decided to test Kraton’s high-performance, polymer-based HiMA™ in the wearing course mixtures. The project took place in Anchorage, where a PG 64E-40 HiMA binder was used in a Superpave mix incorporating hard aggregate. The HiMA mix was placed on 5th and 6th Avenues and cross streets in downtown Anchorage. This project was a standard street resurfacing with a 1.75-inch (44 mm) mill and 2-inch (50 mm) fill. Traffic on 5th and 6th Avenues average from 10,000-15,000 vehicles per day.

To date, performance has been good with minimal damage caused by studded tire wear or traffic loads. In 2019, after four years of traffic, including studded tires, the average rut depths were 0.204 in (5.2 mm) on 5th Avenue and 0.198 in (5 mm) on 6th Avenue. Following the successful project performance, Alaska DOT&PF specified the same PG 64E-40 HiMA binder grade for resurfacing Glenn Highway.

Glenn Highway was paved in 2017, and after two winters, the rut depth was 0.21 in (5.3 mm). Previously, a trial with PG 64-34 and ground tire rubber experienced 0.32 in (8.1 mm) rut depth after two winters, so the HiMA solution reduced rutting by a third. This translates to a 50 percent increase in pavement life before resurfacing is required.

リソース

• Full Case Study (PDF)
• Survey and Economic Analysis of Pavement Impacts from Studded Tire Use in Alaska (2019)