With the continuous construction of transportation infrastructure, intersection nodes have been increasing rapidly, bringing growing numbers of tunnel- and exit-adjacent sections (TEAS) in mountain expressways in China. With the complex variation in the surrounding environment, drivers always face congestion and confusion on tunnel and the exit connecting sections (TECS) without adequate length, meanwhile excessively long TECS create detours. To better provide a sustainable design strategy for TEAS, based on a certain section of expressway in Shaanxi, China, this paper establishes a theoretical calculation model through analysis. The characteristics of traffic flow and drivers’ light adaptation at tunnel exit are obtained through data collection and driving tests, and the length requirements of the tunnel and exit connecting sections (TECS) are discussed. A VISSIM microscopic simulation model is also built under various design schemes and entropy-based multi-attribute decision making (EBMADM) is used to objectively calculate the weights of the four selected evaluation indexes. Then, the design schemes of the TECS with different lengths have been comprehensively evaluated. The results show the match between the evaluation results of EBMADM with theoretical calculations under existing traffic conditions, which proves the rationality of EBMADM in such problems. For more cases, the results of the EBMADM evaluation show a positive correlation between the length of TECS for the best performing design scheme with traffic volume and diverging ratio.

Frequent consecutive lane changes and the barrier effect produced by trucks can always contribute to rapid access to the capacity bottleneck at expressway exits, thereby reducing operational performance. This paper proposes to retrofit the conventional interchange design to reduce lane changes and compares them with conventional design and passenger vehicle and truck separation (PVTS) design from multiple fields via VISSIM numerical simulation, which is developed and calibrated with traffic data collected on the eight-lane expressway in China at four levels of service (LOS). Comprehensive evaluation (CE) results reveal that the PVTS strategy improves operational performance by 10–20% at multilane expressway exits, while lane separation around interchanges also yields a similar gain. However, ramps on both the left and right sides show less effective improvement and are even negative at LOS-A and LOS-B. All PVTS and improved designs produce a better comprehensive improvement ratio with a LOS decrease, and improved designs achieve optimal performance below LOS-B with construction cost taken into consideration.