The main objective of this study was to evaluate the safety effects caused by altering the lengths of deceleration and acceleration lanes at rest areas on expressways in Korea. Although general conclusions can be found through crash-based safety analysis, to examine more specific optimal conditions considering various traffic conditions, this study proposes a novel framework to explore and evaluate crash-based and simulation-based safety performances. For this purpose, the safety performance function (SPF) and crash modification factor (CMF) were developed to reflect real-world safety impacts. To consider nonlinear trends of the parameters, nonlinearizing link functions were introduced into the analysis. Two types of simulation analyses were conducted to (1) find the combination of surrogate safety measures (SSMs) that best fit with the crash-based safety performance results and (2) determine the optimal lengths of deceleration lane and acceleration lanes for different traffic conditions. The results showed that the best length of deceleration lane of a rest area is between 240 and 260 m, depending on the traffic conditions. The results also indicated that the optimal length of acceleration lane of a rest area is between 385 and 400 m, depending on the traffic parameters. The findings of this study could be used to determine the safety solutions with a micro-traffic simulator.

Autonomous driving technology, in which cars recognise their surroundings and drive by way of mechanical control, has attracted much attention. However, before the introduction of autonomous driving technology, there will be a mixture of autonomous and non-autonomous vehicles, which will require a traffic operation management strategy to ensure the safety and operational efficiency of the mixed traffic flow. In response, an operation plan is proposed here to design and operate a managed lane to minimise friction between autonomous and non-autonomous vehicles in the commercialisation phase of autonomous vehicles (AVs). To evaluate this AV managed-lane operation strategy, effectiveness measurements relation to safety, operation efficiency and the environment were derived by conducting a simulation analysis using Vissim software. Then, a value function was developed that reflects the three measurements and their importance weighting values. Using this approach, the paper provides a strategy of optimal AV managed-lane operation that can increase operational efficiency and safety in expressway on/off-ramp areas.