Center for Urban Transportation Research, University of South Florida, 4202 E Fowler Ave CUT 110, Tampa, FL 33620, United States.
Accid Anal Prev. 2011 May;43(3):605-12. doi: 10.1016/j.aap.2010.08.019. Epub 2010 Dec 21.
The safety performance of left-side off-ramps was evaluated by comparing that of right-side off-ramps at freeway diverge areas. Crash records at a total of 11 left-side and 63 similar right-side diverge areas in Florida were collected. Based on the data collected, the traffic conflict study and the cross-sectional comparison of crashes were conducted in this study. Four types of traffic conflicts were identified and counted. The average conflict rates near the ramp area were found to be approximately 10 per 1000 conflicting vehicles. Crash data were compared for the left-side off-ramps with right-side off-ramps by two exit ramp types: one-lane exit and two-lane exit with an optional lane, respectively. The comparisons indicate that the left-side off-ramp did have higher average crash counts, crash rate and percentage of severe crashes, but the difference is only statistically significant for the severe crashes at a 10% level. A crash prediction model for one-lane exit was developed to identify the factors that contribute to the crashes that have been reported for selected freeway segments. The conclusion is consistent with cross-sectional comparison. It is expected that this study could help engineers have a better understanding of left-side off-ramps at freeway diverge area and select the appropriate countermeasures and practical designs.
左侧出口匝道的安全性能通过比较高速公路分流区的右侧出口匝道来评估。在佛罗里达州，共收集了 11 个左侧和 63 个类似右侧分流区的碰撞记录。基于收集的数据，本研究进行了交通冲突研究和事故的横断面比较。确定并计算了四种类型的交通冲突。发现匝道区域附近的平均冲突率约为每 1000 辆冲突车辆 10 次。通过两种出口匝道类型（单车道出口和带可选车道的两车道出口）对左侧出口匝道和右侧出口匝道的碰撞数据进行了比较。比较表明，左侧出口匝道确实具有更高的平均碰撞次数、碰撞率和严重碰撞的百分比，但仅在统计学上对于严重碰撞在 10%的水平上具有显著差异。为单车道出口开发了一个碰撞预测模型，以确定导致所选高速公路段报告的碰撞的因素。结论与横断面比较一致。预计这项研究可以帮助工程师更好地了解高速公路分流区的左侧出口匝道，并选择适当的对策和实际设计。
