Evaluation of techniques to improve the legibility of bilingual Variable Message Signs

This study evaluated a number of techniques that could be employed to reduce the amount of time drivers spend searching and reading bilingual signs. Using a tachistoscope, monolingual and Welsh bilingual participants were presented with various configurations of bilingual signing. The amount of information was varied (i.e. the number of lines) and a number of language-differentiation techniques were implemented. These techniques attempted to aid the perception and recognition of the relevant language and relied either on manipulating the position of the two languages, or by using demarcation (colour, font etc.). With regards to the amount of information presented, it was found that the reading response time for a single line of relevant text within a two-line bilingual sign was not significantly different to the reading response time for a one-line monolingual sign. Thus, participants were able to extract the relevant language from the bilingual sign with no decrement in performance. However, reading response time for a message of two lines of relevant text in a four-line bilingual was significantly longer than the reading response time for a two-line monolingual sign. Thus the amount of information (even if irrelevant) impacted on their performance. With regards to the positioning techniques, grouping the lines by language resulted in a decreased reading response time compared to when the text was grouped by content. In addition, positioning the user’s dominant language at the top of the sign improved reading times for both one and two-line messages on bilingual signs. All the demarcation techniques were successful in reducing reading times on four-line bilingual signs, and it was found that having established a particular pattern of presentation, an unexpected change significantly increased reading time

Surrogate in-vehicle information systems and driver behaviour: Effects of visual and cognitive load in simulated rural driving

The underlying aim of HASTE, an EU FP5 project, is the development of a valid, cost-effective and reliable assessment protocol to evaluate the potential distraction of an in-vehicle information system on driving performance. As part of this development, the current study was performed to examine the systematic relationship between primary and secondary task complexity for a specific task modality in a particular driving environment. Two fundamentally distinct secondary tasks (or surrogate in-vehicle information systems, sIVIS) were developed: a visual search task, designed such that it only required visual processing/demand and an auditory continuous memory task, intended to cognitively load drivers without any visual stimulus. A high fidelity, fixed-base driving simulator was used to test 48 participants on a car following task. Virtual traffic scenarios varied in driving demand. Drivers compensated for both types of sIVIS by reducing their speed (this result was more prominent during interaction with the visual task). However, they seemed incapable of fully prioritising the primary driving task over either the visual or cognitive secondary tasks as an increase in sIVIS demand was associated with a reduction in driving performance: drivers showed reduced anticipation of braking requirements and shorter time-to-collision. These results are of potential interest to designers of in-vehicle systems

Safety implications of a pedestrian protection system - the driver's point of view

Pedestrians can sustain fatal injuries, even in low-speed collisions. Active pedestrian protection systems, such as an Active Bonnet, have been shown to mitigate the outcome of a collision. The study reported here aimed to discover whether such a system could have any negative impacts on the driver. One of the characteristics of the Active Bonnet is that, when deployed, it partially occludes the driver’s visual field. This driving simulator study quantified the amount of disruption to normal driving when the system is deployed, for drivers of three different heights. Curved and straight sections of road were simulated and occlusion time varied between 0.5 seconds and 4 seconds. In general, drivers’ reaction to the deployment of the bonnet was to decrease their speed; this was most noticeable for drivers at the lowest eye-height both in the straight and curved sections of road. On straight sections of road, drivers were able to maintain vehicle speed and lateral control for up to three seconds of partial occlusion of the visual field. For curved sections, this upper threshold was found to be only two seconds, reflecting the higher workload in the curved sections. When occlusion was lifted, drivers tended to then deviate in lane – a possible “panic” effect. As drivers became more familiar with the system, they applied the brakes less. In conclusion, according to the scenarios tested in this study, drivers appear to be able to cope with partial occlusions of two seconds or less and there is some evidence that a panic reaction can be lessened by familiarisation

Are You Used To It Yet? Braking Performance and Adaptation in a Fixed-base Driving Simulator.

During braking-to-stop manoeuvres in a fixed-base driving simulator, the paucity of visual and vestibular cues can lead to driver misperception and produce different patterns of braking response between real and simulated driving. For these reasons, drivers must adapt their behaviour in a simulator to affect a comfortable and efficient braking manoeuvre. Such behavioural adaptation is likely to have negative consequences by increasing a driver’s attentional demand. In this study, 48 participants underwent a series of braking-to-stop manoeuvres in an instrumented vehicle on a test-track. Each participant was instructed to drive at 40mph. A set of traffic lights, on occasions, changed to red as the vehicle was 58m from the lights. Deceleration profiles provided the baseline data. The same scenario was modelled in a fixed-base driving simulator. Two groups, each of 24 participants, one familiar with the simulator from previous investigations and one with no prior simulator experience, underwent the simulated traffic light scenario ten times. This paper suggests a method of objectively assessing driver braking performance between the real and simulated environments. Results appear to suggest that in as little as five or six practice stops drivers can adapt their simulator driving style to closely match that observed in a real vehicle on a test track. However, any process of adaptation from prior exposure to the simulator is short-lived

Image Characteristics and Their Effect on Driving Simulator Validity

Due to financial and computational limitations, the image quality presented in driving simulators is often a trade-off between resolution, pixel density and field of view. The current study examined this trade-off by investigating the effect of image resolution and horizontal field of view on the validity of the Leeds Driving Simulator. There were three levels of pixel density: low (3.6 arc min per pixel), high (2.6 arc min per pixel) and real world, and four levels of field of view: narrow (50°), medium (120°), wide (230°) and real world. Results seemed to show that widening the field of view improved the validity of speed choice and lane position between simulated and real world driving conditions, whilst there was no significant effect of image resolution

The Effects of an Eco-Driving Interface on Driver Safety and Fuel Efficiency

Real-time, in-vehicle guidance on eco-driving is likely to produce substantial improvements in vehicle fuel economy. However, the benefits of such in-vehicle systems should be achieved without impairing driver safety. A simulator study evaluated both visual and haptic eco-driving feedback systems, which provided advice on gas pedal usage. Hill driving scenarios with variable traffic density were used to test drivers’ prioritization of safe and fuel-efficient driving. A visual, second-order display and a haptic force feedback gas pedal created the smallest errors in gas pedal usage and so maximized fuel efficiency. The visual display increased time spent looking away from the road, implying reduced driver safety. Participants were worse at eco-driving in more demanding, high traffic conditions. Drivers appeared to prioritize safety over eco-driving, however safety margins were shorter in the high density traffic condition, despite the degradation in eco-driving performance. The findings suggest which modality could be most appropriate for presenting in-vehicle eco-driving guidance, and hint that these systems should advise drivers based on the prevailing traffic conditions

Deal or no deal: can incentives encourage widespread adoption of intelligent speed adaptation devices?

Given the burden of injury, economic, environmental and social consequences associated with speeding, reducing road traffic speed remains a major priority. Intelligent speed adaptation (ISA) is a promising but controversial new in-vehicle system that provides drivers with support on the speed-control task. In order to model potential system uptake, this paper explores drivers’ preferences for two different types of ISA given a number of alternative fiscal incentives and non-fiscal measures, using a stated preference approach. As would be expected with such a contentious issue, the analysis revealed the presence of significant variations in sensitivities and preferences in the sample. While a non-negligible part of the sample population has such strong opposition to ISA that no reasonable discounts or incentives would lead to them buying or accepting such a system, there is also a large part of the population that, if given the right incentives, would be willing or even keen to equip their vehicle with an ISA device

Bilingual Variable Message Signs: A Study of Information Presentation and Driver Distraction

Research on static bilingual signs has confirmed increasedreading times compared to their monolingual counterparts; however there islittle empirical research on bilingual Variable Message Signs (VMS). Thestudy reported here evaluates the effect of various bilingual VMSconfigurations on driver behaviour and safety. The aim of the study was todetermine whether or not the visual distraction associated with bilingualVMS signs of different configurations (length, complexity) impacted ondriving performance. The results suggest that four-line bilingual VMS signscomprising 2 lines of text in each language are read by both monolingualand bilingual drivers in a manner that more closely approximates a two-linemonolingual sign. This being the case it is likely that the deployment offour-line bilingual signs on Welsh motorways is unlikely to result in asignificant reduction in safety

The Effectiveness of Safety Campaign VMS Messages - A Driving Simulator Investigation

This report outlines an off-road trial of the effectiveness of Safety Campaign Messages (such as “Watch Your Speed”) sometimes displayed on Variable Message Signs (VMS) throughout the U.K.’s motorway network. Eighty drivers took part in the driving simulator study. It primarily investigated the effectiveness of the individual messages and how their presence affected driver behaviour towards more critical Tactical Incident Messages (TIM), such as those that might warn of an impending hazard. Both the content and concentration of the Safety Campaign Messages were varied. The Safety Campaign Messages in themselves were not especially beneficial, in that drivers did not significantly modify their driving style purely on the advice of the messages. However, witnessing the odd VMS carrying such a message appeared to improve driver alertness to the context of the VMS and consequently response to a TIM became more timely under these conditions. Yet, if the frequency of Safety Campaign Messages was overly high, drivers became jaded with the VMS content and their ability to act appropriately to a TIM degraded