Center for Transportation Studies, Department of Civil and Environmental Engineering, Thornton Hall D101, 351 McCormick Road, University of Virginia, Charlottesville, VA 22904, United States.
Center for Sustainable Transportation Infrastructure, Department of Civil and Environmental Engineering, 706 Benedum Hall, University of Pittsburgh, Pittsburgh, PA 15213, United States.
J Safety Res. 2018 Feb;64:121-128. doi: 10.1016/j.jsr.2017.12.016. Epub 2017 Dec 29.
Adaptive signal control technology (ASCT) has long been investigated for its operational benefits, but the safety impacts of this technology are still unclear. The main purpose of this study was to determine the safety effect of ASCT at urban/suburban intersections by assessing two different systems.
Crash data for 41 intersections from the Pennsylvania Department of Transportation (PennDOT), along with crash frequencies computed through Safety Performance Functions (SPFs), were used to perform the Empirical Bayes (E-B) method to develop crash modification factors (CMF) for ASCT. Moreover, a crash type analysis was conducted to examine the safety impact of ASCT on a regional scale and the variation of safety among type of crashes observed.
The results from this study indicated the potential of ASCT to reduce crashes since the Crash Modification Factor (CMF) values for both ASCT systems (SURTRAC and InSync) showed significant reductions in crashes. Average CMF values of 0.87 and 0.64 were observed for total and fatal and injury crash categories at a 95% confidence level, and results were consistent between systems. While a reduction in the proportion of rear end crashes was observed, the change was not determined to be statistically significant. The overall distribution of crash types did not change significantly when ASCT was deployed.
The results indicate that safety benefits of ASCT were generally consistent across systems, which should aid agencies in making future deployment decisions on ASCT.
自适应信号控制技术（ASCT）长期以来因其运行效益而受到研究，但该技术的安全影响仍不清楚。本研究的主要目的是通过评估两种不同的系统来确定城市/郊区交叉口 ASCT 的安全效果。
宾夕法尼亚州交通部（PennDOT）的 41 个交叉口的碰撞数据以及通过安全绩效函数（SPF）计算的碰撞频率被用于执行经验贝叶斯（E-B）方法，以开发 ASCT 的碰撞修正因子（CMF）。此外，还进行了碰撞类型分析，以检查 ASCT 在区域范围内的安全影响以及观察到的碰撞类型之间的安全变化。
本研究的结果表明 ASCT 具有降低碰撞的潜力，因为两种 ASCT 系统（SURTRAC 和 InSync）的碰撞修正因子（CMF）值都显示出碰撞的显著减少。在 95%置信水平下，总碰撞和致命及伤害碰撞类别的平均 CMF 值分别为 0.87 和 0.64，并且两种系统的结果一致。虽然观察到后碰撞比例降低，但变化未被确定为具有统计学意义。当 ASCT 部署时，碰撞类型的总体分布没有显著变化。
结果表明，ASCT 的安全效益在系统之间基本一致，这应该有助于机构在未来的 ASCT 部署决策中做出决策。
