Optimal Design Alternatives of Guide Signs for Expressway Segments with Consecutive Dense Exits

The guide signs at expressway play an important role in conveying road information to drivers. To study the reasonable setting of guide signs at expressway with consecutive dense exits, firstly, a bidirectional eight-lane expressway segment model were constructed with three exit ramp scenarios: “single exit”, “consecutive double exits”, and “consecutive triple exits”. Two groups of schemes (standard group and optimized group) for guide signs were set, resulting in 10 different experimental comparison schemes. Secondly, thirty-two licensed drivers were recruited to conduct experimental tests using a driving simulation platform. Then four types of experimental data related to driving operations are collected: participants’ subjective perception, vehicle operation safety, driving maneuvers smoothness, and cumulative eye movement comfort. These data were used to compare and analyze the 10 different design schemes of guide signs, determining the optimal design alternatives for expressway segment with three exit ramp scenarios. The comparative analysis of the experimental data across the three exit ramp scenarios revealed that factors such as ramp spacing, guide signs content, and placement distance of guide signs significantly impact vehicle safety and comfort. There is an inverse relationship between ramp spacing and both vehicle safety and driving comfort. The participants’ visual recognition efficiency is enhanced by optimizing the content and placement distance of the guide sign effectively, further ensuring the safe and smooth operation of vehicles. This study can effectively reduce traffic conflicts at expressway exit ramps and decrease the incidence of traffic accidents. Additionally, it provides solid theoretical support for the design and sustainable development of expressway traffic facilities.