Lane restriction system to reduce the environmental cost of urban roads

https://doi.org/10.1016/j.trd.2022.103575Get rights and content

Abstract

Separating trucks from passenger vehicles on urban roads is a task that has attracted attention in many countries because of its capacity to improve traffic performance and optimize traffic resources. A lane-restriction system was designed in this study to improve the performance of urban roads and reduce environmental costs, including total fuel consumption and exhaust emissions. As environmental costs are systemic and must be considered in urban road networks, we first determined the critical factors of lane restriction from the perspectives of urban traffic and the environment. We also designed a dedicated vehicle classification, application scope, and evaluation index system considering the environmental costs of an urban road with a lane-restriction system. Two case studies were conducted to verify the effectiveness. The results suggest that the proposed lane-restriction system significantly improves traffic performance and reduces the environmental costs of the urban road network.

Introduction

Many studies have indicated that trucks perform differently from passenger vehicles in various traffic and environmental circumstances (Booto et al., 2021, Perugu et al., 2016), making the system of separating trucks from passenger vehicles, referred to as the separation system, necessary. The separation system, first used on freeways (Abdelgawad et al., 2011, Dong et al., 2019), separates these two types of vehicles and prevents them from disturbing each other on the road. Because of different structures and functions of urban roads and freeways, there are critical differences between urban roads and freeways which may lead to different designs for the separation system. Specifically, because of the existence of intersections, the vehicle speed on urban roads is much lower than that on freeways. Besides, since urban roads are built among human settlements, people pay more attention on the environmental costs of urban roads. Both of them make the traffic impacts and environmental costs of urban roads different from those of freeways. Considering its remarkable contribution to improvements in efficiency and safety, the separation system was recently implemented on urban road intersections and was proven to be environmentally friendly (Ma et al., 2021). However, it only considered separation systems at intersections, and the separation system for road sections and its traffic and environmental impact on the entire network were not considered. Therefore, the present study proposes a lane-restriction management that is specially designed for the separation system on urban road sections considering its systematic traffic impacts and environmental costs, with the aim of enriching separation facilities for the urban freight management and reducing the traffic and environmental costs of urban road systems.

Lane restriction constrains certain types of vehicles within specific lanes to separate their traffic flow. For example, one lane-restriction system separates trucks from passenger cars by their loads and usage types, making them travel in separated freeway lanes to avoid severe truck accidents (Dong et al., 2019). In general, lane restriction separation systems are used on freeways rather than urban roads (Abdelgawad et al., 2011, Fontaine, 2008). However, urban roads have traffic facilities similar to lane restrictions, such as bus lanes and rapid bus transit. According to our research, lane restrictions dedicated to urban separation systems have not been addressed because urban road networks usually involve many aspects that are different from freeways, thus increasing the difficulty and complexity of urban lane-restriction research. Specifically, compared to that on freeways, the lane-restriction system on urban roads faces greater challenges in the model formulation and simulation setting from four aspects. First of all, building a simulation model of an urban road network involves constructing more road sections and a number of intersections with entrance and exit links, which is more difficult than building a freeway simulation model. Second, some studies have shown that urban roads contribute more environmental cost than freeways (e.g., Figliozzi, 2011, Zambon et al., 2016). For example, Figliozzi found that urban road networks emit more carbon dioxide than freeways because of its greater travel demands and level of congestion (Figliozzi, 2011). Since people pay great attention to the environmental cost and urban life quality, the consideration of urban environmental costs brings challenges in evaluating the lane-restriction system on urban roads. Third, different from the cases of freeways where counting equipment counts people’s travel demand, in urban road networks people travel from one building to another and no counting equipment works, which makes the travel demand acquisition more difficult and laborious. Last but not least, the challenges in the simulation setting come from the travel behavior of urban travelers. For example, there are more stringent speed limits for urban travelers. The differences in both model formulation and simulation setting make the result on urban roads different from that on freeways. This study explores the possibility of implementing lane restrictions on urban roads and proposes a framework for urban lane-restriction systems, providing the possibilities of further applications such as dedicated signal control, traffic management, vehicle management, and evaluation systems. For example, a dedicated signal control for heavy vehicles can be applied to a well-designed lane-restriction system. Traffic management and vehicle management will be much easier because of the separation of vehicles, and an evaluation system can be established to assess the lane-restriction system. Moreover, since urban living environments are critical to citizens, urban road environmental costs have recently attracted increased attention (Coulombel et al., 2018, Xue et al., 2015). Therefore, this study also investigates the impact of lane restrictions on the environment and proposes a dedicated vehicle classification and evaluation index system that considers urban road environmental costs.

This study aims to fill the research gap identified in the literature review on separation and lane-restriction systems. The contributions of this study are as follows:

  • We propose a methodology to build a lane-restriction system specifically designed for urban roads and analyze its traffic performance and environmental impacts on the urban traffic system. A framework for urban lane-restriction systems is established, allowing further applications and localized implementations. Road safety, transportation efficiency, road maintenance, and environmental costs of lane restrictions are considered.

  • We present a localized vehicle classification, an application scope, and an evaluation index system for the proposed lane restriction. The vehicle classification considers dynamic performance, physical size, axle load, and psychological pressure, rather than vehicle usage. The application scope indicates the road type and traffic flow components to which the lane restriction is applied. The evaluation index system includes the average speed, delay, lane-changing time, fuel consumption, and vehicle exhaust emissions.

  • We provide a method to evaluate local lane-restriction implementation by using simulation models. The effectiveness of the proposed urban lane-restriction system implemented on an urban road section and an urban road network was assessed. The test results suggest that the proposed lane-restriction system and its supporting facilities significantly improve traffic performance and reduce the environmental cost of the urban road network.

Section snippets

Literature review

Over the past few decades, separation studies have become the focus of many researchers. For instance, Middleton et al. (2005) investigated the economic feasibility of separation systems. Dong et al. (2019) proposed an evaluation method for separation systems at freeway toll stations. However, most separation studies and applications are for freeways and cannot be directly implemented on urban roads because of different traffic circumstances. For example, road accessibility, travel demand, and

Research domain and framework

The lane-restriction system separates trucks from passenger vehicles and allows them to travel in different lanes. Therefore, it is suitable for urban roads with multiple lanes. Fig. 1 gives some examples of the lane-restriction system. Fig. 1(a), 1(b) and 1(c) illustrate three examples that may be suitable for different scenarios.

In this study, we provide a methodology to implement lane-restriction systems on urban roads, which can be applied to most scenarios. For better illustration, we

Impacts of lane restriction on urban roads

First, we determined the impact of the lane-restriction system on urban roads. Environmental costs and transportation impacts, including road safety, transportation efficiency, and road maintenance, are the most significant aspects of concern for urban roads. We briefly analyze these aspects below.

Vehicle classification and application scope for lane restriction on urban roads

Lane restriction is a traffic management measure that constrains specific types of vehicles within specific lanes to separate the traffic flow and must be coordinated with appropriate vehicle classification and application scope. Based on the impacts of urban lane restrictions on urban traffic, we propose the vehicle classification and application scope for lane-restriction systems on urban roads by considering the dynamic performance, physical size, axle load, and psychological pressure.

Evaluation index for lane restriction on urban roads

We employed and modified an index system proposed for urban intersection separation systems to evaluate the performances of lane-restriction systems (Ma et al., 2021). Specifically, since we need not compare the economic efficiency of lane-restriction system and that of other separation systems, the economic indices were deleted. The speed variation was removed and the lane-changing index was highlighted because many urban traffic studies suggest that lane-changing maneuvers has a much greater

Case studies

Vehicles are classified as light and heavy vehicles according to the proposed dedicated vehicle classification for urban lane-restriction systems, whereas the benchmark classification categorizes them as passenger vehicles and trucks according to their loads and usage. We checked the proposed urban lane restriction using these two classifications separately. Further, we assessed the advantages of the proposed classification using a real urban road section and small urban network as two examples.

Conclusions and future expectations

In this study, we proposed a lane-restriction system for urban roads. We first analyzed the impact of the lane-restriction system on urban road traffic. Transportation efficiency, road safety, road maintenance, and environmental costs were considered. As lane restrictions also incorporate supporting traffic facilities, such as vehicle classification and evaluation systems, we further proposed a dedicated vehicle classification considering the dynamic performance, physical size, axle load, and

CRediT authorship contribution statement

Jie Ma: Conceptualization, Methodology, Software, Writing – original draft. Xiaofei Wu: Data curation, Validation, Writing – review & editing. Jiehui Jiang: Visualization, Investigation, Supervision.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Funding: This study is supported by Ministry of Education of the People’s Republic of China Humanities and Social Sciences Youth Foundation (No. 22YJCZH123), the Natural Science Foundation of Jiangsu Province (No. BK20220846), China Postdoctoral Science Foundations (No. 2021M690614; 2021T140112), China Natural Science Foundation (No. 72204078), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX20_0163); and Henan Provincial Science and Technology Research

References (35)

Cited by (0)

View full text