菲尼克斯曾尝试用一种看似简单的方法来对抗极端的城市热岛效应：让街道反射更多的阳光。该市2020年的“凉爽路面试点项目”在8个街区的住宅道路部分路段涂上了一层颜色更浅、反光性更强的密封剂。其目标是减少沥青吸收的太阳能，进而降低夏季高温会使户外表面变得危险滚烫的各个街区的温度。
Phoenix tried a deceptively simple way to fight extreme urban heat: make its streets reflect more sunlight. The city’s 2020 Cool Pavement Pilot Program coated sections of residential roads in eight neighborhoods with a lighter, more reflective seal. The goal was to reduce the amount of solar energy absorbed by asphalt and, in turn, lower temperatures across neighborhoods where summer heat can make outdoor surfaces dangerously hot.
但这项实验揭示了一个不太显眼的权衡。反光路面确实使路面温度大幅降低，但它也将更多的太阳辐射反射回了附近的人身上。对于直接在处理过的路面上行走的行人来说，这意味着尽管路面本身温度下降了，但他们受到的辐射热暴露却出现了可测量的增加。菲尼克斯转向反光街道2020年，菲尼克斯选取了8个街区的部分路段作为试点，每个市议会选区一个。
But the experiment revealed a less obvious trade-off. The reflective pavement did make the road surface substantially cooler, yet it also sent more solar radiation back toward people nearby. For pedestrians walking directly on the treated pavement, that meant a measurable increase in radiant heat exposure even as the pavement itself cooled. Phoenix turns to reflective streetsIn 2020, Phoenix selected portions of eight neighborhoods, one in each City Council district, for the pilot.
该处理被应用于已经需要进行路面维护的街道上，这使得该市能够在不创建单独道路施工项目的情况下测试这种涂料。该市与亚利桑那州立大学的研究人员合作，以检查这种处理如何影响当地环境的几个方面。
The treatment was applied to streets that were already due for pavement preservation, allowing the city to test the coating without creating a separate road-construction program. The city partnered with researchers from Arizona State University to examine how the treatment affected several aspects of the local environment.
据亚利桑那州立大学称，研究人员测量了地表、空气和地下温度，以及平均辐射温度，该温度体现了一个人从周围表面和太阳体验到的组合辐射热。研究小组还监测了路面的反射率随时间的变化情况。最初的实地考察涵盖了大约36英里的住宅街道，并且该研究详细检查了3个街区中经过处理和未处理的区域。研究人员使用了配备温度传感器的车辆、直升机飞行的热成像以及名为MaRTy的移动气象站，来测量行人在地面高度所经历的状况。
According to Arizona State University, researchers measured surface, air, and subsurface temperatures, along with mean radiant temperature, which captures the combined radiant heat a person experiences from surrounding surfaces and the sun. The team also monitored how the pavement's reflectivity changed over time. The initial field campaign covered about 36 miles of residential streets, and the research examined treated and untreated areas across three neighborhoods in detail. Researchers used vehicles equipped with temperature sensors, thermal imaging from helicopter flights, and a mobile weather station called MaRTy to measure conditions experienced at pedestrian level.
路面更凉爽，辐射暴露更热从测试来看，路面表面的优势显而易见。在正午和下午，经过处理的道路温度比传统沥青低10.5度到12度。在日出期间，温差略低，平均为2.4度。温差归因于路面更高的反射率。虽然深色沥青吸收了大部分太阳能，但较浅的物质将其中的一部分反射了出去。地下温度平均也低4.8度。然而，当应用于人类时，同样的特性却造成了劣势。
Cooler pavement, hotter radiant exposureFrom the tests, there was a clear advantage at the surface of the pavement. At noon and in the afternoons, the temperature of the roads with the treatment was 10.5° to 12° cooler than the traditional asphalt. During sunrise, the temperature difference was slightly lower, 2.4° on average. The temperature difference was due to the pavement’s higher reflectance. While the dark asphalt absorbed most of the solar energy, the lighter substance reflected some of it away. Temperatures of the subsurface also had an average of 4.8° cooler. However, the same quality caused a disadvantage when applied to humans.A 2023 study in Nature Communications found that reflective pavement can substantially reduce surface temperatures, but its effect on human heat exposure is more complicated.
发表在《自然·通讯》杂志上的一项2023年研究发现，反光路面可以大幅降低表面温度，但其对人类热暴露的影响则更为复杂。在菲尼克斯，研究人员发现，在正午和下午左右，反光路面上的平均辐射温度更高，因为较浅的表面将更多的太阳辐射反射向路面上的人。这种效应因时间和地点而异，在相邻的人行道上没有检测到显著差异。
In Phoenix, researchers found that mean radiant temperature was higher over reflective pavement around noon and during the afternoon, as the lighter surface reflected more solar radiation toward people on the roadway. The effect varied with the time of day and location, with no significant difference detected on adjacent sidewalks.
该研究还发现，反光路面显著降低了表面温度，而2米空气温度的差异仍然很小，在测量仪器的不确定性范围内。在日出前和日落后，经过处理的路面上的平均辐射温度略低。这些发现表明，反光路面可以在不一定减少行人日间辐射热暴露的情况下冷却路面。更凉爽道路的局限性菲尼克斯的实验说明了为什么降低路面温度并不一定等于减少人们受到的热暴露。
The study also found that reflective pavement significantly lowered surface temperatures, while differences in 2-meter air temperature remained small and within the uncertainty of the measuring instruments. Before sunrise and after sunset, mean radiant temperature was slightly lower over the treated pavement. The findings show that reflective pavement can cool the road surface without necessarily reducing daytime radiant heat exposure for pedestrians. The limits of a cooler roadThe Phoenix experiment illustrates why reducing pavement temperature is not necessarily the same as reducing heat exposure for people.
道路在将其紧上方空间反射更多阳光的同时，温度也可以变得更凉爽。随着涂料随时间老化，这种效应也发生了变化。长达10个月的测量显示，太阳反射率从最初的大约33%至38%下降到19%至30%，尽管它仍然比未处理的沥青更具反射性，后者的反射率约为12%。
A road can become cooler while reflecting more sunlight into the space immediately above it. The effect also changed as the coating aged over time. Measurements over 10 months showed solar reflectivity falling from roughly 33% to 38% initially to 19% to 30%, although it remained more reflective than untreated asphalt, which had a reflectivity of about 12%.More recent research has continued to examine the trade-off.
更新的研究继续审视了这种权衡。发表在《建筑与环境》杂志上的一项2026年研究发现，菲尼克斯的反光路面继续产生更凉爽的表面，但却增加了正午的平均辐射温度，这强化了考虑行人暴露而不是仅仅依赖路面温度的重要性。对于菲尼克斯来说，这个教训并不一定意味着反光路面失败了。相反，实验表明，在哪里以及如何部署凉爽路面才是关键。
A 2026 study in Building and Environment found that reflective pavement in Phoenix continued to produce cooler surfaces, but increased midday mean radiant temperature, reinforcing the importance of considering pedestrian exposure rather than relying only on pavement temperature. For Phoenix, the lesson is not necessarily that reflective pavement failed. Instead, the experiment showed that where and how cool pavement is deployed matters.
行人交通较少的道路可以拥有更低的地表和地下温度，而不会必然增加人类的热暴露。然而，行人交通繁忙的区域将需要遮阳设施或树木，以弥补反射的辐射。最后，这个试点项目成为了菲尼克斯采纳的整体道路维护方法的一部分。因此，菲尼克斯的经验表明，反光路面可以帮助应对城市热岛效应，尽管更凉爽的路面并不一定能让行人感到更凉爽。
Roads with little pedestrian traffic can have lower surface and subsurface temperatures without necessarily increasing human heat exposure. Areas with heavy pedestrian traffic will, however, need shading or trees in order to compensate for reflected radiation. In the end, the pilot project became part of the overall road maintenance approach adopted by Phoenix. Thus, Phoenix’s experience suggests that reflective pavement can help address urban heat, although cooler pavement does not necessarily make pedestrians cooler.