Traffic signs play a major role on the national highway system because they provide users with important information such as warnings, regulations, and directions. To ensure sign visibility at night, the Manual on Uniform Traffic Control Devices (MUTCD) requires transportation agencies to meet minimum sign retroreflectivity levels through a sign maintenance program. To better understand current trends, the researchers conducted an extensive literature search that showed that expected sign life and nighttime inspection are the most used methods, followed by blanket replacement. The literature does not typically discuss how these methods are implemented. Thus, the research team also contacted three of the four largest state-maintained highway systems in the United States (North Carolina, Virginia, and South Carolina) to discuss sign maintenance programs, implementation issues, and best practices. The authors describe in this article the findings and conclusions drawn from these case studies that may help other agencies improve their sign maintenance practices.

中文翻译：

---

三个标志管理项目案例分析

交通标志在国家公路系统中发挥着重要作用，因为它们为用户提供重要信息，例如警告、法规和方向。为确保夜间标志的可见性，统一交通控制设备手册 (MUTCD) 要求运输机构通过标志维护计划达到最低标志逆反射水平。为了更好地了解当前趋势，研究人员进行了广泛的文献搜索，结果表明预期标志寿命和夜间检查是最常用的方法，其次是更换橡皮布。文献通常不讨论这些方法是如何实现的。因此，研究小组还联系了美国四个最大的由国家维护的高速公路系统中的三个（北卡罗来纳州、弗吉尼亚州、和南卡罗来纳州）讨论标志维护计划、实施问题和最佳实践。作者在本文中描述了从这些案例研究中得出的发现和结论，这些发现和结论可能有助于其他机构改进他们的标志维护实践。