The effects of an edgeline on speed and lateral position: a meta-analysis

doi:10.1016/S0001-4575(03)00090-3

Accident Analysis & Prevention

Volume 36, Issue 4, July 2004, Pages 671-682

https://doi.org/10.1016/S0001-4575(03)00090-3 Get rights and content

Abstract

This paper presents a meta-analysis of studies that have evaluated the effects of an edgeline on speed and lateral position of motorised road users. Together with many other study characteristics, 41 estimates of the effects of an edgeline on speed and 65 on lateral position were extracted from the studies. The results of the evaluation studies show a great variety in effects. Both negative and positive effects on speed and lateral position were found; amongst others, increases in speed up to 10.6 km/h, as well as decreases in speed up to 5.0 km/h, and shifts of the lateral position towards the centre of the road up to 30 cm, as well as shifts towards the edge of the road up to 35 cm. Further analyses resulted in the determination of study characteristics that influence the effects of an edgeline on speed and lateral position. It is concluded that the effects of an edgeline on speed are related to the presence of a centreline. Applying an edgeline to a road without a centreline increases the speed of road users, and replacing a centreline by an edgeline decreases the speed. Results with respect to adding an edgeline to a road with a centreline were unclear. Another conclusion is that shoulder width and road environment contribute to the effects of an edgeline on lateral position. In combination with wide shoulders or buildings and/or trees next to the road, edgelines lead to shifts of the lateral position towards the edge of the road, and in combination with narrow shoulders or open fields, edgelines lead to shifts towards the centre of the road.

Introduction

Since the early nineties, the road safety policy in The Netherlands is strongly influenced by the concept of “sustainable safety”. The objective of sustainable safety is to have a traffic system in which the probability of an accident is very limited. Where an accident cannot be prevented, serious injury should be virtually excluded. A sustainably safe road traffic system has (1) a road infrastructure that has been adapted to the limitations of human capacity through proper road design, (2) vehicles that are technically equipped to simplify driving and to give all possible protection to vulnerable human beings, and (3) road users that have been properly educated, informed, and, where necessary, deterred from undesirable or dangerous behaviour (see Koornstra et al., 1992, Van Schagen and Janssen, 2000, Wegman, 1998 for an elaborate description of the sustainably safe road traffic system).

Road design is regarded as a powerful instrument to influence road user behaviour. Unfortunately, the knowledge about the exact relationship between road design and the behaviour of individual road users is still very limited due to the fact that this relationship has been studied merely by means of small-scaled studies. On the basis of a single small-scaled study, it is often difficult to predict general effects because the study results depend on the circumstances in which the experiments took place (e.g. road type, road environment). Furthermore, the results of a single study usually do not give any insights into the range of possible effects, nor into variables that can influence the magnitude of the effect. In fact, general effects of road design on road user behaviour can only be established on the basis of reviews. However, reviews on the relationship between road characteristics and road user behaviour are hardly available. The available reviews (e.g. Fildes and Lee, 1993, Martens et al., 1997, OECD, 1990) summarise existing studies, but the authors were not able to deduce general effects of moderating variables. To overcome above-mentioned problems with respect to reviews and small-scaled studies, the aim of this study was to increase the knowledge of the effects of environment on road user behaviour by means of a meta-analysis.

An inventory of studies that have investigated the relation between aspects of the environment (e.g. road design, road environment) and aspects of road user behaviour (e.g. speed, lateral position) shows that most studies are aimed at the relationship between road design and speed (e.g. Brenac, 1989, Botterill and Thorensen, 1996, Carlsson and Lundkvist, 1992). Therefore, the relationship between road markings, in specific edgelines, and speed was chosen as subject of the meta-analysis. Since many of the studies that have investigated this relationship have also paid attention to the relationship between road markings and lateral position, this aspect of road user behaviour was included in the meta-analysis as well. This selection was based on several criteria, among which the relevance for road safety research, especially for the concept of sustainable safety, and the number of available studies. Research has shown that marking is the most important road characteristic with respect to the recognition of the road type one is driving on (Janssen et al., 1999, Van Schagen et al., 1998). This is an important finding for the “categorisation” of different road types, which is part of the concept of sustainable safety. Marking can thus be used to make a distinction between different road types. In this way, road users will know on which type of road they are driving and hence what behaviour is expected from them, e.g. the speed at which they are permitted to drive. Aiming at the harmonisation of road markings in Europe, the European project COST 331 is performed. Task 400—a part of this project—reports on the effects of road markings on driver behaviour (Mäkinen et al., 1999). Driving on roads without or with very poor road markings was compared to driving on roads with various types of markings (e.g. continuity, width, retroreflection). The effects of road markings on driver behaviour turned out to be generally small. It was concluded that large-scale field studies with accident data are needed to make a reliable assessment of the safety effects of different types op road markings.

This paper summarises the results of studies that have evaluated the effects of an edgeline on speed and lateral position of motorised road users. See Fig. 1 for an example of an edgeline. The main questions that are discussed in the paper include:

(1)
What are the best current estimates of the effects on speed and lateral position of an edgeline?
(2)
To what extent are the magnitudes of these effects influenced by study characteristics (e.g. research design, width of the edgeline, road environment and shoulder width)?

Section snippets

Retrieval of studies

The studies included in the meta-analysis were retrieved by means of a systematic literature survey. The literature survey was conducted by using the International Transport Research Documentation (ITRD), the computerised databases from several research institutes (e.g. SWOV, TRB and VTI), tables of contents of journals (e.g. Accident Analysis and Prevention, Transportation Research Record and Ergonomics) and reference lists from relevant studies. Keywords that were used for searching the

Publication bias

Inspection of a funnel graph can indicate whether there is publication bias in the dataset (Light and Pillemer, 1984). Publication bias occurs when results that are ‘unfavourable’ (e.g. results showing increases in speed) or not statistically significant are not or sparsely present in the published documents. If any of these forms of publication bias are present, they can affect the shape of the distribution of data points in a funnel graph. The idea of the funnel graph is based on the

Discussion

The aim of this study was to make a contribution to the knowledge of the effects of road design on road user behaviour. With that objective, a meta-analysis of 65 experiments that have evaluated the effects of an edgeline on speed and lateral position of motorised road users was performed. The experiments were carried out in The Netherlands or the United States of America. Regarding several study characteristics (e.g. year of the experiment, research design, pavement width and alteration of

References (27)

I.N.G.L. Van Schagen et al.
Sustainable safety in The Netherlands
IATSS Res.
(2000)
Botterill, R., Thorensen, T.R., 1996. Effects of road width and roughness on vehicle speeds on two way two lane rural...
T. Brenac
Speed, safety and highway design
Réch. Transports Secur.
(1989)
Carlsson, A., Lundkvist, S.O., 1992. Wide Lanes on a Major Road. Road User Effects of Alternative Roadway Painting on a...
Czar, M., Jacobs, D., 1972. Center line marking patterns. In: Roadway Delineation Systems, NCHRP Report 130, pp....
Dart, O.K., 1965. A study of roadside delineator effectiveness on interstate highways. In: Proceedings of the Highway...
De Waard, D., Steyvers, F.J.J.M., 1995. Carriageway Marking in Rural Areas: An Experiment With Edgelines (Wegbelijning...
De Waard, D., Steyvers, F.J.J.M., Brookhuis, K.A., 2000. Visual Information and Driving Behaviour: Results of a Driving...
Fildes, B.N., Lee, S.J., 1993. The Speed Review: Road Environment, Behaviour, Speed Limits, Enforcement and Crashes....
Gifi, A., 1983. HOMALS User’s Guide. Department of Datatheory, Leiden University,...

Hultman, B.A., McGee, H.W., 1972. Evaluation of raised pavement markers on a rural curve. In: Roadway Delineation...

Janssen, W.H., Claessens, F.M.M., Muermans, R.C., 1999. The Design of ‘Sustainably Safe’ Road Categories: Evaluation of...

Jorol, N.H., 1962. Lateral vehicle placement as affected by shoulder design on rural Idaho highways. In: Proceedings of...

Cited by (38)

Self-Explaining Roads: Effects of road design on speed choice
2024, Transportation Research Part F: Traffic Psychology and Behaviour
One of the leading principles for road design is the notion of Self-Explaining Roads (SER). According to this notion, the design and layout of the road environment should automatically elicit behavior that is appropriate for that type of road. The current study investigated the effects of the road environment (i.e., the presence of particular road elements such as the presence/absence of edge lines, and a physical separation between driving lanes) on driving speed choice in the Netherlands for roads in- and outside the city limits (ICL and OCL). A total of 462 participants (all car drivers) were exposed to either 152 ICL or 152 OCL pictures of road environments for either a short (300 ms in Experiment 1, 200 ms in Experiment 2) or long duration (1500 ms) and indicated as fast as possible which speed they would drive given the road environment they viewed. All images were labeled with respect to the presence or absence of particular road elements. A linear mixed model was used to determine the effects of road elements on speed choice and response time. The results showed that the presence of certain road elements impacted the speed chosen. For example, inside the city limits, relative to no bicycle lane, a bicycle lane painted on the road reduced driving speed while a separate bike lane increased the speed chosen. Also, central line markings (relative to no line marking) and a road made of asphalt (relative to pavers) were associated with higher speeds. Outside city limits, having multiple lanes (versus one lane) was related to higher speeds and having two driving directions without separation (versus a one-way road) was related to lower speed choices. Importantly, exposure duration (200 /300 ms versus 1500 ms) only had a marginal effect, indicating that road users generally only need a brief glimpse of the road to be able to decide what speed to drive. Consistent with the principles of SER, we conclude that categorization and the associated speed decision is fast, operating within a single glance and is impacted by the road elements present in the environment. Finally, we believe our method constitutes a valuable tool in road design, as it allows one to efficiently and effectively gauge the impact of various road elements in large population samples.
Interrelatedness of steering and lateral position parameters: Recommendations for the assessment of driving performance
2024, Journal of Safety Research
Introduction: Loss of attention leads to less steady driving within the lane and is one of the main causes of road accidents. To improve road safety, vehicle-based parameters such as steering wheel angle and lateral position are used to objectively assess driving performance, especially in monotonous driving tasks. Method: The present driving simulator study investigated the extent to which eight commonly used parameters are independent indicators of driving performance. Fifteen participants undertook a monotonous highway driving task for 1 h. Four steering angle parameters were examined: average steering angle (ASA), standard deviation of steering angle (SDSA), steering angle range (SAR), and steering reversal rate (SRR); as well as four lateral position parameters: mean lateral position (MLP), standard deviation of lateral position (SDLP), lateral position range (LPR), and the out-of-lane duration. Measurements were averaged across 2-minute epochs. Repeated measures correlation analysis evaluated the similarity between each parameter, and the variance inflation factor test evaluated the multicollinearity of all the parameters. Results: The results demonstrated that some parameters are highly correlated and should not be used together to assess driving performance. It is recommended that the optimal combination is ASA and SAR to assess steering angle, and SDLP and out-of-lane to assess lateral position. Out-of-lane, as a factor directly contributing to road safety, is recommended because it has the least correlation with other parameters. Practical Applications: If implemented, these recommendations may improve the assessment of driving performance in future studies.
Empirical evaluation of change in crash risk due to lane marking reallocation: A case study in Kochi City, Japan
2023, IATSS Research
Lane markings are considered an essential component of a road system. As highlighted in previous studies, they are directly linked to efficiency and safety. The rearrangement or reallocation of lane markings can be an economical way to improve efficiency. However, such changes could influence driver behavior. Thus, there is a tradeoff between efficiency and safety. Through a case study in Kochi City, Japan, this study evaluated the change in crash risk caused by a lane marking reallocation. Video data were collected before and after the implementation of a new road layout (achieved by reallocating lane markings) that was intended to mitigate traffic congestion at a signalized intersection. Based on the video data, PICUD (Possibility Index for Collision with Urgent Deceleration), a surrogate safety index used to estimate collision risk, was estimated for lane changes and conflicts between leading and following vehicles in the through lane. In particular, it was confirmed that the collision risk between a lane-changing vehicle and a leading vehicle in the through lane was reduced due to the reduction in traffic density caused by the new road layout. In addition, the results indicate that the PICUD value tends to decrease (i.e., the crash risk tends to increase) with increasing speed of the following vehicle relative to the leading vehicle. Overall, the improvement in safety after the implementation of the new road layout was marginal and statistically insignificant. Therefore, this study highlights the necessity of incorporating speed control measures, such as speed limits, along with congestion alleviation measures in order to enhance safety.
Gaze and steering strategies while driving around bends with shoulders
2022, Applied Ergonomics
The installation of shoulders on rural roads to create more forgiving roads encourages drivers to cut corners on right-hand bends, but the underlying mechanisms are poorly understood. Since eye movements and steering control are closely coupled, this study investigated how the presence of a shoulder influences drivers' gaze strategies. To this end, eighteen drivers negotiated right-hand bends with and without a shoulder on a simulated rural road. In the presence of a shoulder, participants modified their visual sampling of the road by directing their gaze further inside the bend. At the same time, their lane position was deviated inward throughout the bend and the vehicle spent more time out of the lane. These results suggest that the shoulder influences the visual processes involved in trajectory planning. Recommendations are made to encourage drivers to keep their eyes and vehicle in the driving lane when a shoulder is present.
An ANN-based framework for estimating inconsistency in lateral placement of heterogeneous traffic
2022, Physica A: Statistical Mechanics and its Applications
The lateral placement is the transverse position of a moving vehicle across the carriageway width. Studies on lateral placement have gained importance over time specifically for two reasons; (1) lateral placement data has become a crucial input in most of the traffic flow simulation models, and (2) detection of wheel positions helps in determining the riding quality and the distressed portions on a pavement surface. In the case of heterogeneous traffic flow and loosely enforced lane discipline, the estimation of lateral placement of vehicles deals with additional complexity. In such cases, vehicles take any lateral position left empty by other surrounding vehicles while moving in a mixed traffic stream. This results in an inconsistent lateral trajectory of vehicles. Further, this inconsistency is primarily governed by the subject vehicle type and other prevailing factors of the traffic stream. On this background, the present study forwards a Neural Network-based approach to quantify the inconsistency associated with the lateral placements chosen by different vehicle categories in a mixed traffic situation. In addition, a sensitivity analysis revealed how the inconsistency in lateral placement varies suggestively with the change in traffic and road geometric factors.
On the relationship between road safety research and the practice of road design and operation
2019, Accident Analysis and Prevention
How do the findings of road safety research affect the practice by which the road infrastructure is built and operated? The question is seldom asked. I discuss the complexities of the research-practice symbiosis in the light of two historical anecdotes. These allow me to point out several issues of concern.
My general conclusion is that the relationship, as it evolved over time, is unpremeditated and occasionally dysfunctional. Issues of concern are the lightness with which decisions affecting road-user safety can be based on opinion that is unsupported by evidence, that such opinions can trump inconvenient evidence, that research findings can be willfully distorted or disregarded, that questionable results can be given a ring of consensual truth, and that the questions which research asks and what findings get published are at times influenced by external interest. In sum, the concern is that practice is not sufficiently evidence-based. Road users have a right to expect that decisions substantially affecting their safety take into account fact-based expectation of safety consequences. It is therefore time to endow the research-practice relationship with a premeditated and purposeful structure.

View all citing articles on Scopus

View full text