# Evaluation of Adjustment Effects of Highway Guide Signs Based on the TOPSIS Method
## 1 Introduction  
With the rapid development of the economy, the demand for road transportation has surged, accompanied by swift road network expansion. China's highway network,for instance, has grown from 85,000 km in 2011 to 183,600 km in 2023, forming a large-scale and increasingly complex network. This expanding infrastructure has provided a solid foundation for diverse travel modes [1]. As the primary medium for conveying critical road information, highway guide signs are essential in minimizing driver errors and reducing risks. However, statistics reveal that accidents involving traffic signs and markings constitute 60% of all traffic accidents, underscoring how inadequate or inaccurate signage can substantially elevate driving hazards [2]. For instance, missing or unclear signs may lead drivers to miss exits or fail to anticipate sharp curves. Therefore, optimizing the design and placement of highway guide signs is an important issue in current road traffic management [3; 4]. With the further expansion of the highway network, the opening of new or extended highways has altered driving routes, requiring timely adjustments to guide signs along the routes to ensure the continuity of network information. In densely connected highway networks, guide signs not only need to direct drivers to single destinations but also provide multi-level information to prevent missed exits or incorrect turns. These demands place higher requirements on the design and setup of signage [5; 6]. Therefore, it is essential to establish a scientific evaluation method and indicator system to comprehensively analyze the effectiveness of these adjustments. Existing research on the evaluation of traffic signs primarily focuses on the impact of design elements, information load thresholds, and driver characteristics on the effectiveness of traffic sign usage, as well as the methods used to assess traffic sign systems. Studies on design elements often emphasize how features such as color, font size, shape, and contrast influence the visibility and comprehension speed of drivers [7; 8; 9]. Researchers assess the effectiveness of these elements under various conditions, including low light, poor weather, and complex road environments [10; 11]. [PERSON] et al. [12], applying human ergonomics principles, developed an evaluation model encompassing information needs, comprehension, and information load. In terms of setting information thresholds, studies show that excessive information can increase drivers' visual load, potentially leading to adverse driving behaviors and even causing traffic accidents [13; 14; 15; 16]. [PERSON] et al. [17] demonstrated through experiments that traffic signs with varying amounts of information significantly affect driving load. [PERSON] et al. [18] observed a significant reduction in legible reading distance as the information load on variable message signs increased. Notably, when the number of messages reached six, drivers' comprehension accuracy declined sharply. [PERSON] et al. [19] studied the effectiveness of bilingual guide signs (in Chinese and English) for drivers with different language backgrounds on Chinese highways. [PERSON] et al. [20] noted that cantilever signs can accommodate up to five pieces of information, while gantry signs can hold up to nine. Different characteristics, such as age and education, also influence the visibility and comprehension of traffic signs [21; 22; 23; 24]. [PERSON] et al. [25] investigated the effect of personal characteristics and traffic sign design on traffic sign usability and found that four of the five personal characteristics studied (e.g., age, education level, and driving experience) correlated significantly with traffic sign usability. [PERSON] et al. [26] examined the relationship between drivers' personal characteristics and their familiarity with and comprehension of traffic signs.