我们信赖路标保障安全。闪烁标志、路面标记和路灯都在试图让驾驶员保持警惕。但如果路面本身需要修缮，该怎么办？这是华盛顿州贝尔维尤市一个下坡路口面临的问题。联邦公路管理局（FHWA）的一份案例研究显示，该市尝试了几种常见的修正措施，均无成效。于是，它在2004年10月更换了路面铺装。该路口的事故减少了78%，与事故相关的成本下降了83%。这个故事说明了当驾驶员必须在坡道上停车时，路面状况有多么重要，同时也有一些值得了解的局限性。
We trust road signs to keep us safe. Flashing signs, road markers, and street lights all try to keep drivers alert. But what if the road itself needs fixing? That was the question at a downhill intersection in Bellevue, Washington. A case study from the Federal Highway Administration (FHWA) revealed that the city tried several common fixes, to no avail. So, it changed the pavement in October 2004. Crashes at the intersection declined 78%, and costs related to crashes declined 83%. The story shows how important a road surface can be when drivers have to stop on a slope, and it has a few limits worth knowing.A downhill approach and fixes that fell shortThe trouble spot was an intersection where drivers came downhill.
下坡路段与收效甚微的修正措施事故多发点是一个驾驶员下坡行驶的路口。该机构指出，路口固有的挑战包括停车视距有限，以及下坡路段制动距离增加。贝尔维尤市并未忽视这一问题。案例研究指出，该市已在坡底设置了大型闪烁警告标志。还设置了路面标记、新路灯和凸起路面标记。所有这些都是为了让该路段更安全。但这些初步措施并未产生预期效果。这是一个重要的教训。标志可以告诉驾驶员减速，但无法在驾驶员需要停车时帮助轮胎抓地。
The agency notes intersections have built-in challenges, including limited sight distance to stop and additional braking distance on downhill approaches. The problem was not lost on Bellevue. The city had already tried a large flashing warning sign at the bottom of the grade, the case study noted. It had also put in road markers, new street lights, and raised pavement buttons. All of them were to make the spot safer. But those initial measures didn’t produce the desired results. That is an important lesson. A sign can tell a driver to slow down, but it cannot help a tire grip the road when the driver needs to stop. What a grippy surface doesIn October 2004, Bellevue applied a high friction surface treatment, or HFST, to the downhill approach to the intersection.
高摩擦路面的作用 2004年10月，贝尔维尤市在通往该路口的下坡路段铺设了高摩擦路面处理（HFST）。案例研究指出所用产品为“Tyre-grip”。这种处理改善了路面的摩擦特性，使车辆能更好地应对视距受限和下坡制动距离增加等状况。摩擦无非是轮胎与路面之间的抓地力。这就像从穿光底鞋换成穿深纹路的鞋。
The case study identifies the product as Tyre-grip. This type of treatment improves the friction characteristics of the pavement, allowing vehicles to better handle conditions such as restricted sight distance and the need for more braking distance on downgrades. Friction is nothing more than the grip between a tire and the road. It’s like changing from slick shoes to shoes with deep treads. The same document also points out that while most HFST projects are on curves, intersections can benefit as well.
同一文件还指出，虽然大多数高摩擦面层处理（HFST）项目位于弯道，但路口同样可以受益。贝尔维尤就是一个很好的例子。该处理措施应用于下坡路口进口段，而非弯道。数据说明什么据联邦公路管理局（FHWA）称，该处理措施使该路口的事故减少了 78%，事故成本降低了 83%。通俗地说，原本 100 起事故会减少到约 22 起。
Bellevue is a good example of this. The treatment was on a downhill intersection approach rather than a curve. What the numbers sayAccording to the FHWA, the treatment reduced crashes at the intersection by 78% and the cost of crashes by 83%. In plain terms, 100 crashes before would shrink to about 22 after. That’s a lot of change for a single intersection.
对单个路口而言，这是巨大的变化。但有必要提醒一下。该摘要未报告原始事故次数或研究时长。因此，这些数字应被视为单一地点的前后对比结果，而非对所有道路的承诺。其他变化，包括交通流转移，也会影响单一地点的事故数量，这也是为什么一个案例不足以得出定论。更广泛的研究显示什么一个案例只是故事，而非证据，因此查看更大规模的研究会有帮助。
But a word of caution is helpful here. The summary does not report the raw crash counts or the duration of the study period. So these numbers should be seen as the before-and-after result of one site and not as a promise for every road. Other changes, including traffic shifts, can also influence crash numbers at a single location, which is why one story is not enough to resolve the question. What wider research showsOne site is a story, not proof, so it’s helpful to look at bigger studies. A 2020 FHWA research report by David K. Merritt, Craig A. Lyon, Bhagwant N. Persaud, and Helga N. Torres studied hundreds of installations in Arkansas, Georgia, Kentucky, Louisiana, Pennsylvania, and West Virginia.
大卫·K·梅里特、克雷格·A·里昂、巴格旺特·N·佩尔索和海尔加·N·托雷斯撰写的 2020 年联邦公路管理局研究报告，研究了阿肯色州、佐治亚州、肯塔基州、路易斯安那州、宾夕法尼亚州和西弗吉尼亚州的数百处安装点。研究团队使用了处理前后的事故数据。他们发现了显著效益，特别是在雨天事故方面。对于弯道，研究人员还发现效益大小与三个因素持续相关：摩擦力提升了多少、道路有多繁忙、以及处理前预期会发生多少事故。
The team used crash data from before and after. They found important benefits, especially for crashes in wet weather. For curves, the researchers also saw a consistent link between the size of the benefit and three things: how much friction improved, how busy the road was, and how many crashes were expected before treatment. However, there’s a fly in the ointment.
然而，美中不足的是，该研究针对的是弯道和匝道，而非贝尔维尤那样的路口。因此，它支持在弯道和匝道上采用该处理措施的总体思路，但无法证实贝尔维尤的数据，也无法显示该处理措施在路口的表现。尽管如此，这两个来源指向同一方向。贝尔维尤的结果令人鼓舞，而更广泛的研究支持在驾驶员最需要抓地力的地方增加抓地力这一思路。
That study was for curves and ramps, not intersections like Bellevue’s. So it backs up the general idea of the treatment on curves and ramps, but it doesn’t confirm Bellevue’s numbers or show how the treatment performs at intersections. Still, the two sources point in the same direction. Bellevue’s result is encouraging, and the wider research backs the idea of adding grip where drivers need it most.