宾夕法尼亚州611号公路上的一处急弯一直存在一个常规道路标志和标线无法解决的安全问题。当雨水覆盖路面时，驾驶员面临路面摩擦力低和道路几何线形复杂的双重挑战，增加了打滑和驶离道路的风险。2007年，宾夕法尼亚州交通部尝试了一种更有针对性的解决方案：在该弯道约800英尺的路段铺设高摩擦路面表层。
A sharp curve on Pennsylvania's Route 611 had a persistent safety problem that conventional road signs and markings could not solve. When rain covered the pavement, drivers faced a combination of low surface friction and difficult road geometry, increasing the risk of skidding and leaving the roadway. In 2007, the Pennsylvania Department of Transportation (PennDOT) tried a more targeted solution: a high-friction surface treatment on about 800 feet of the curve.
美国联邦公路管理局的记录显示，铺设后的八年里，处理过的位置未发生任何湿滑路面事故，与此前的事故记录相比变化巨大。这一结果成为早期的一个重要案例，表明在特定危险点改善轮胎与路面的抓地力，无需重建整条道路即可带来安全效益。611号公路上的危险弯道这段公路位于北安普敦县611号州道，地处伊斯顿以南约五英里，在一个名为格朗德霍格洛克斯的区域。
The Federal Highway Administration (FHWA) recorded no wet-pavement crashes at the treated location for the eight years following installation, a dramatic change from its earlier crash history. The result became an important early example of how improving the tire-to-road grip at a specific trouble spot could deliver safety benefits without reconstructing an entire roadway.A dangerous curve on Route 611This stretch of highway was in Northampton County on State Route 611, about five miles south of Easton, in an area called Groundhog Locks. On the southbound side, the highway included a sharp horizontal curve that existed on a two-lane rural road, which had narrow 9-foot travel lanes and no shoulders.
南行方向，这条双车道乡村公路包含一处急弯，车道狭窄，仅9英尺宽，而且没有路肩，使得该路段尤其难以驾驶。该弯道的超高设置不足；此外，弯道内还有一个交叉路口。由于路权问题，宾夕法尼亚州交通部无法拓宽或重建这条道路。
This made the site especially difficult to navigate. The curve was not adequately superelevated; furthermore, there was an intersection within the curve itself. It was impossible for PennDOT to widen or reconstruct the road due to right-of-way issues.
美国联邦公路管理局的案例研究显示，南行方向10年内发生了13起湿滑路面事故。宾夕法尼亚州交通部和美国联邦公路管理局的其他材料则引用了不同的时间段和总数，包括10年内20起湿滑路面事故和5年内21起，这反映了不同的评估区间。一致的结论是，雨天事故是该弯道反复出现的问题。
FHWA's case study reports 13 wet-pavement crashes over 10 years in the southbound direction. Other PennDOT and FHWA materials cite different periods and totals, including 20 wet-pavement crashes over 10 years and 21 over five years, reflecting different evaluation windows. The consistent finding was that wet-weather crashes were a recurring problem at the curve.
宾夕法尼亚州交通部此前已尝试过相对常规的措施，包括增设警告标志、之字形导向标志和改善路面标线。
PennDOT had already attempted relatively conventional measures, including additional warning signs, chevrons, and improved pavement markings.
他们没有充分解决根本的摩擦问题。弯道比直道路段需要更大的侧向摩擦力，因为车辆在转弯时必须抵抗侧向力。潮湿条件使得路面难以提供足够的摩擦力，从而更容易发生打滑和水滑。相对于弯道在公路系统中所占的比例，弯道发生的致命车祸数量高得不成比例。一段800英尺长的高摩擦路面2007年6月，该部门在南向弯道约800英尺的路段上铺设了HFST，铺设方向与过去事故发生方向相同。
They did not adequately address the underlying friction problem. Curves require more lateral friction than straight sections because vehicles must resist sideways forces while cornering. Wet conditions make it difficult for there to be enough friction, hence making skidding and hydroplaning more likely. Curves account for a disproportionately high number of fatal crashes relative to their share of the highway system. An 800-foot strip of high-friction pavementThe HFST treatment was applied to about 800 feet of the southbound curve in June 2007 in the same direction where the past accidents took place.
这是该部门首次使用HFST，作为试点项目。该处理使用了煅烧铝矾土骨料和环氧树脂。HFST是一层薄薄的高抗滑骨料。普通骨料会被交通磨损而变得光滑，而煅烧铝矾土则因其保持摩擦力的能力而被选用。该处理带来了明显的改善。在HFST处理之前，平均防滑值为24。HFST处理后，平均防滑值约为75。2010年7月，平均防滑值为71。
This was the first time the department had utilized HFST, serving as a pilot project. The treatment used calcined bauxite aggregate and epoxy resin. HFST is a thin layer of highly skid-resistant aggregate. Unlike regular aggregates, which can become polished by traffic, calcined bauxite is chosen for its ability to retain friction. The treatment produced a clear improvement. Prior to HFST treatment, the average skid number was 24. After HFST treatment, the average number was around 75. In July 2010, the average skid number was 71.
处理后湿滑路面事故为零关键结果出现在路面处理之后。美国联邦公路管理局还指出，该路段在2007年处理后的八年内未发生事故。这促使宾夕法尼亚州交通部超越试点项目，于2012年对另外14个湿滑路面事故高发地点进行了处理。在美国联邦公路管理局“每日都重要”倡议的帮助下，宾夕法尼亚州交通部继续增加处理地点的数量。
Zero wet-road crashes after treatmentThe key result came after the road surface was treated. FHWA also notes that the site remained crash-free during eight years after treatment of the road in 2007. This encouraged PennDOT to go beyond the pilot project and treat 14 other spots with high incidences of wet-pavement crashes in 2012. With help from the FHWA’s Every Day Counts initiative, PennDOT continued to increase the number of treated areas.
到2015年底，宾夕法尼亚州交通部已处理了150个地点。宾夕法尼亚州交通部自己后来的评估也发现了同样令人鼓舞的结果。在有足够后续事故数据的47个处理地点中，该机构报告称湿滑路面事故、车辆偏离道路事故、固定物体碰撞事故以及事故总数均显著减少。在最初的611号公路地点，宾夕法尼亚州交通部报告事故频率降低了100%。
By the end of 2015, PennDOT had treated 150 sites. PennDOT's own later evaluation found similarly encouraging results. Among 47 treated locations with enough follow-up crash data, the agency reported significant reductions in wet-road, roadway-departure, fixed-object, and total crashes. At the original Route 611 location, PennDOT reported a 100% reduction in crash frequency.
611号公路表明，公路安全改善并不总是需要重建；有时，修改路面就足够了。这种高摩擦面层处理（HFST）在该小型道路项目上的成功，为全州范围内的安全措施确立了方法。
Route 611 shows that highway safety improvements do not always require reconstruction; sometimes, modifying the pavement is enough. The success of HFST on this small road project set up a statewide approach to safety.