The impact of perceptual countermeasures on driving behavior in rural-urban transition road segments: A driving simulator study

This driving simulator study investigated the impact of perceptual countermeasures on driving behavior by creating perceptual effects via pavement markings. Two different marking schemes (i.e. Optical Circles and Optical Bars) were tested separately for road transitions between rural and urban areas where the speed limit reduces from 70 kph to 50 kph. The tested treatments were intended to achieve combined perceptual effects (i.e. increase drivers attention, perceptual speed and perceptual road narrowing effect) independently. Data were analyzed for 44 participants (30 men and 14 female). The study results showed that the speed was reduced significantly for both road marking treatments, however, the Optical Circle scenario in which circles with increasing size were implemented was the most effective solution. Moreover, standard deviation of acceleration/deceleration and lateral position were not found to be significant due to the treatments. This indicates that drivers did not decelerate or evade vehicles unsafely when confronting the road markings. The obtained results recommend Optical Circles to policy makers for further evaluation as a low-cost speed management tool.Scopu

Speed perception and actual speed in a driving simulator and real-world: A validation study

Background: Driving simulators have become an effective research tool in traffic safety, but the validity of results obtained in simulated environments remains a debated issue of high importance. Objective: The objective of this study is to validate a fixed-base driving simulator for speed perception and actual speed and to support its application in traffic safety studies. Method: The study consisted of two experiments to test the external and subjective validity of the driving simulator in absolute and relative terms. External validity was framed into two parts i.e. for speed perception and actual speed. In the first part, the external validity was assessed based on the speed perception observations from forty volunteers that participated in the study. Speed estimations for four different requested speeds (50, 70, 80 and 100 kph) were recorded under two conditions: speedometer hidden and speedometer revealed. In the second part, the external validity was assessed based on the comparison of actual speed observations from field and simulator. The subjective validity of the simulator setting was assessed through a questionnaire. Results: Results from both experiments showed correspondence of the driving behavior between the simulator and real-world settings. In general, the profiles for estimated speed and actual speed followed a significantly similar tendency and indicated relative validity in both experiments. Moreover, external absolute validity for speed perception was established on all the requested speeds with speedometer hidden while only for the requested speed of 80 kph with speedometer revealed. Participants' evaluation of the quality and performance of the driving simulator supported the subjective validity of the simulator setting. Conclusion: The fixed-base driving simulator used in this study can be considered as a useful tool for research on actual speed and speed perception.Qatar National Research Fund, Qatar FoundationScopu

Investigating the impact of dynamic merge control strategies on driving behavior on rural and urban expressways – A driving simulator study

Harsh decelerations and abrupt lane changes of drivers on the outer expressway lane in response to merging platoon vehicles from on-ramps increase the crash- and congestion risk on expressways. Several merge control approaches are worldwide implemented. However, there is a gap in knowledge which driving behaviors determine whether a particular merge control approach is best for a rural or urban expressway. This study tests a number of dynamic merge control strategies, such as lane control signalization (eventually combined with variable speed limits (VSL), on a 4-lane urban and rural expressway to measure the behavioral responses of drivers being directly exposed to platoon merging from on-ramps. Subsequently, a comparison was made with the driving behaviors in response to static merge control (e.g. merge warning signs or road marking treatment). The driving behavior of 66 drivers from the State of Qatar was recorded in a driving simulator and analyzed by means of a within-subject repeated measures analysis with univariate statistics. The results suggest that dynamic merge control is more effective for rural expressways considering the higher traffic speeds. The earlier lane changes contributed to smooth maneuvers and gradual speed reductions on the rural expressway and improved safe driving behavior as compared to static merge control. In contrast, the dynamic merge control did not deliver additional safety benefits on urban expressways and can be substituted by a low-cost static merge control approach. Policymakers aiming to improve traffic safety at expressway merging sections are advised to take the speed characteristics of the local expressway into account before implementing dynamic merge control. - 2019 Elsevier LtdThis publication was made possible by the NPRP award [ NPRP 9-360-2-150 ] from the Qatar National Research Fund (a member of The Qatar Foundation ). The statements made herein are solely the responsibility of the author[s]. The authors also would like to thank Wim Ectors for data extraction support.Scopu

Drivers’ estimation of their travelling speed: a study on an expressway and a local road

Correctly estimating the travelling speed is essential for safety on the roads to ensure safer interactions with other drivers and to avoid violations of traffic regulations. Therefore, it is important to create understanding of the pattern of speed perception of drivers and the influencing factors. This study invited 40 drivers to participate in a field experiment measuring speed perception. The experiment was conducted using a test car equipped with high fidelity Global Positioning System (GPS). Data were collected for two settings (hidden versus revealed speedometer) and four requested speeds (50, 70, 80 and 100 km/h). An analysis of variance test was conducted along with separate t-tests and cumulative distributions for each speed independently. The results clearly show that there were significant differences in perceived speed between a hidden and revealed speedometer, between the first and second trial and among all the requested speeds. Participants drove significantly faster for all the requested speeds in the hidden speedometer setting. This shows that participants underestimated their speed. In case of complex situations, drivers may not be able to rely on speedometers and may cause a violation of law, unintentionally. Therefore, it is recommended to jurisdictions to consider these results while making decisions regarding speed management. - 2019, - 2019 Informa UK Limited, trading as Taylor & Francis Group.This publication was made possible by the NPRP award (NPRP 9-360-2-150) from the Qatar National Research Fund (a member of The Qatar Foundation).Scopu

Drivers� crossing behaviour between express and local lanes with soft separation: A driving simulator study

In different countries, hard separation is adopted as a technique to separate express and local lanes. However, in case of an incident, especially on the express lane, traffic jams can occur as there is no escape route. Emergency services are then required instantly to remove the obstruction. In some cases, even traffic diversion needs to be organized leading to time loss and which may possibly also affect the traffic in adjacent lanes. In this paper, an alternative flexible geometric design approach called �soft separation� is evaluated having less side-effects in case of such calamities. A virtual environment using a driving simulator is used to evaluate 4 different types of soft separation. More specifically, driver behavior and driver temptations to cross different types of soft separation on the express lane are studied. These include: (1) a solid double line (2) cross hatch marking (3) tubular delineators and (4) vegetation / grass strip. Moreover, for each of the soft separation types, drivers were exposed to two different traffic conditions. In the first traffic condition, other vehicles in front did not cross the separation from express to local lanes whereas in the second condition, they did so. Results indicate that tubular delineators and the vegetation strip are more effective in restricting drivers to cross the separation. Implications for road design practice are given. � 2018, Gioacchino Onorati Editore. All rights reserved.Higher Education Commission, PakistanScopu

Investigating the Impacts of Graphical Route Information Panel Layouts on Drivers’ Comprehension and Response Time

Graphical route information panels (GRIPs) are an alternative to conventional text-based variable message signs to address different traveler information needs. Since drivers are traveling at higher speeds on the motorways, they have to quickly comprehend and correctly respond to the graphical information displayed on a GRIP. Design elements like the shape of the route map, the meaning of colors indicating congestion and the font sizes of main and minor destinations along the route can influence the comprehension times of drivers. In this study, GRIPs with two purposes (congestion information and event destination information) were presented to 49 Belgian drivers in a computer-based task. All GRIPs were presented on an abstract and naturalistic motorway network shape. Half of the GRIPs were presented with congestion-related colors (red-only or red–orange), and the other half were presented with additional destinations being displayed in different or same font sizes to facilitate drivers visual search on the GRIP. Firstly, travel information statements were presented to the participant, followed by a displayed GRIP layout. Afterward, the participant had to indicate as fast as possible whether the subsequently shown GRIP confirmed the same travel statement. The subjects’ response accuracy and response times were recorded to assess drivers’ quick comprehension of the graphical content. The results of a repeated-measures ANOVA revealed that for GRIP displaying congestion, the red-color element (and not the map shape) significantly reduced drivers response times. A survey among participants also revealed a preference for two-color congestion information, if shown on an abstract map shape. An abstract map shape in combination with different font sizes for major and minor destinations improved drivers’ comprehension and response times to the GRIP, whereas different destination font sizes displayed on a naturalistic map had the contrary effect. The results highlight the importance of graphical design elements with respect to the information purpose.This publication was made possible by an NPRP Award (NPRP 9-360-2-150) from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors. Furthermore, the authors would like to thank Pieter Verslype for collecting the data.Scopu