爱荷华州锡达拉皮兹市一座繁忙的桥梁成为了司机的反复麻烦点，尤其是在雨天或结冰时路面抓地力下降。2012年之前的几年里，该地点记录了54多起事故，促使交通官员寻找一种既能提高安全性又不必关闭主要城市州际公路的解决方案。
A busy bridge in Cedar Rapids, Iowa, became a recurring trouble spot for drivers, especially when rain or ice reduced the road surface's grip. In the years before 2012, more than 54 crashes were recorded at the location, prompting transportation officials to look for a solution that could improve safety without shutting down a major urban interstate.
根据联邦公路管理局（FHWA）的说法，爱荷华州交通部（IDOT）于2012年6月在该桥梁上施加了高摩擦面层处理（HFST），使测得的抗滑阻力大幅增加。在随后的一年里，该地点仅记录了四起事故。一座湿滑路面成为安全隐患的桥梁该项目实施于锡达拉皮兹市跨越锡达河的一座五合一桥梁群上，属于380号州际公路的一部分。
According to the Federal Highway Administration (FHWA), the Iowa Department of Transportation (IDOT) applied a high-friction surface treatment (HFST) to the bridge in June 2012, dramatically increasing the measured skid resistance. Within the following year, the site recorded only four crashes.A bridge where wet pavement became a safety problemThe project was carried out on a five-in-one bridge complex spanning the Cedar River in Cedar Rapids, part of Interstate 380.
该桥梁群包含四座桥梁结构和一座大坝，而关注的路段是横跨河流的六车道城市高速公路。该路段日均通行量约8.5万辆，其中包括约7800辆重型卡车。该地点的几个特点要求对牵引力控制给予特别关注。通往桥梁的匝道涉及频繁变道，而车速对于弯道和路面可用的摩擦力来说过高。
The complex includes four bridge structures and a dam, while the section of interest is the six-lane urban highway crossing the river. It carries around 85,000 vehicles a day, including about 7,800 heavy trucks. Several features of the site called for special attention to traction control. Ramps leading to the bridge involved frequent lane changes, while vehicle speeds were high for the curve and the pavement's available friction.
2008年春至2012年春期间，该地点发生了54多起事故，其中包括28起伤亡事故。有8起涉及半挂车。一起特别严重的事故涉及一辆卡车冲出桥梁护栏并在桥下起火。一次道路安全审计发现了另一个警示信号：现有路面的抗滑数值在30多和40多。这很重要，因为路面摩擦力有助于轮胎在制动、转弯和其他操作过程中保持与路面的接触。
Between spring 2008 and spring 2012, the location experienced more than 54 crashes, including 28 injury crashes. Eight involved semi-trailers. One particularly serious incident involved a truck that went over the bridge rail and caught fire below. A road safety audit found another warning sign: skid numbers on the existing pavement were in the 30s and 40s. That mattered because pavement friction helps tires maintain contact with the road during braking, turning, and other maneuvers.
发表在《事故分析与预防》上的研究发现，随着防滑性能的提高，湿路面事故率往往会下降，这凸显了路面抓地力与交通安全之间的联系。
Research published in Accident Analysis & Prevention has found that wet-pavement crash rates tend to decline as skid resistance increases, highlighting the connection between pavement grip and traffic safety.
该处理几乎立即改变了桥面的摩擦力。HFST 与重铺路面的做法不同，它还涉及使用一种聚合物粘结剂，将优质骨料与路面粘结在一起，形成能够提供更高摩擦水平的表面。美国联邦公路管理局（FHWA）将该处理归类为一种安全干预措施，旨在解决因雨雪天气、车速或道路设计导致摩擦力不足地点的摩擦力不足问题。对爱荷华州官员而言，这座桥是一个测试案例，因为对于在寒冷气候下的州际公路桥梁使用 HFST 存在疑虑。
The treatment changed the bridge's friction almost immediatelyHFST differs from the practice of resurfacing a road. It also involves using a polymer binder that bonds the high-quality aggregate with the road surface to create a surface that can offer a higher friction level. FHWA classifies the treatment as a safety intervention that addresses the problem of inadequate friction at sites where friction becomes insufficient due to wet weather, speed, or design of the roadways. For Iowa officials, the bridge was a test case because there were doubts about using HFST on an interstate bridge in a cold climate.
该州不确定该处理在大流量交通和重型卡车通行下会如何表现，因此爱荷华州交通部（IDOT）先在其校园内测试该处理，以评估 HFST 的性能。
The state was not sure how the treatment would behave with high traffic volume and heavy trucks, therefore IDOT first tested the treatment on its campus to evaluate how HFST would perform.
摩擦力的变化是即时的。安装前的测量值在 30 多和 40 多，安装后立即跃升至 90 多和 100 出头。此后几个月这些数值大致保持在同一水平。一年多后，测量值仍在 80 多到 100 出头。这种改善不仅仅是粗糙化路面带来的短暂效果。FHWA 的案例研究显示，仅进行喷砂处理只能使摩擦力暂时提升至 60 多中段，而 HFST 提供了实质性更高且更持久的摩擦力水平。
The change in friction was immediate. Measurements that had previously been in the 30s and 40s jumped into the 90s and low 100s immediately after installation. Those values remained at roughly the same level for several months afterward. More than a year afterward, measurements were still in the 80s to low 100s. The improvement was not just a short-lived result of roughening the surface. FHWA's case study showed that shot-blasting alone produced a temporary increase to around the mid-60s, while HFST provided a substantially higher and more persistent level of friction.
一年内发生 4 起事故，而之前约四年发生 54 起最直观的变化体现在事故记录上。处理后一年内，该地点仅报告 4 起事故，且仅 1 起涉及人员受伤。相比之下，在安装 HFST 前的约四年里，该桥记录了 50 多起事故。这一显著减少帮助说服 IDOT 认定 HFST 不仅适用于这座桥，还可推广应用。
Four crashes in a year, compared with 54 beforeThe most visible change came in the crash record. In the year after the treatment, only four crashes were reported at the site, and just one involved an injury. In comparison, the bridge recorded more than 54 crashes during the roughly four years before HFST was installed. That marked reduction helped persuade IDOT that HFST could be useful beyond this bridge.
警方报告称事故数量减少且严重程度降低，而维护人员随后建议在存在类似安全问题的其他地点采用该处理措施。该项目耗资约 49.4 万美元，覆盖 1.8 车道英里，相当于南北向 I-380 大桥六车道中 0.3 英里的路面。联邦公路管理局（FHWA）预估该处理措施的预期使用寿命为 8 至 10 年，大致效益成本比为 3.8。
Police officers reported fewer and less severe crashes, while maintenance staff later advocated using the treatment at other locations with similar safety problems. The project cost about $494,000 and covered 1.8 lane miles, equivalent to 0.3 miles of roadway across the six lanes of the northbound and southbound I-380 bridge. FHWA estimated an expected treatment life of eight to 10 years and an approximate benefit-cost ratio of 3.8.
尽管如此，爱荷华州的经验并不意味着每次高摩擦面层处理（HFST）安装后的事故减少都能自动归因于路面处理。发表在《建设设施性能期刊》上的一项针对九座桥梁的单独研究发现，高摩擦面层铺设后事故总体呈下降趋势，但也警告称，这种减少不能完全归因于面层铺设。对爱荷华州而言，这座桥梁成为了一个早期示范，展示了聚焦的路面干预如何在不重建结构、不改变州际公路线形的情况下，解决一个棘手的安全问题。
Still, the Iowa experience does not mean every crash reduction after an HFST installation can automatically be attributed to the pavement treatment. A separate study of nine bridges published in the Journal of Performance of Constructed Facilities found an overall downward trend in crashes after high-friction overlays but cautioned that the reduction could not be completely attributed to the overlays. For Iowa, the bridge became an early demonstration of how a focused pavement intervention could address a difficult safety problem without rebuilding the structure or changing the interstate's alignment.