Christer Ahlström


Picture of Christer Ahlström

Christer Ahlström works with acquisition, processing and analysis of data, with particular interest in biomedical engineering aspects of driver inattention and driver sleepiness. He especially enjoys bridging the gap in interdisciplinary collaborations involving technology, medicine and behavioral science.

Education:

PhD in Biomedical Engineering, Linköping University.

MSc in Computer Science and Engineering, Linköping University.

Research results from Christer


Changes in glance behaviour when using a visual eco-driving system: A field study

While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate...

Evaluation of methods for the assessment of attention while driving

The ability to assess the current attentional state of the driver is important for many aspects of driving, not least in the field of partial automation for transfer of control between vehicle and driver. Knowledge about the driver's attentional...

Local changes in the wake electroencephalogram precedes lane departures

The objective of this exploratory study is to investigate if lane departures are associated with local sleep, measured via source-localized electroencephalography (EEG) theta power in the 5-9 Hz frequency range. Thirty participants drove in an...

Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes, it is important to understand driver related contributing factors. The overall aim of the Vehicle Driver Monitoring project was to advance the understanding of two such factors; sleepiness and cognitive distraction. The...

Minimum Required Attention: A Human-Centered Approach to Driver Inattention

Objective: To propose a driver attention theory based on the notion of driving as a satisficing and partially self-paced task and, within this framework, present a definition for driver inattention.Background: Many definitions of driver inattention...

Cyklisters interaktion med extrautrustning, infrastrukturen och andra trafikanter: En...

How cyclists interact with the infrastructure, and how they integrate the handling of additional tasks, is dependent on the surrounding traffic situation and the cyclists’ characteristics. To study these relationships, a semi-controlled field study...

The severity of driver fatigue in terms of line crossing: a pilot study comparing day-...

Introduction: The overall aim of this study is to compare day-time driving with night-time driving looking at line crossings during self-reported sleepiness and long blinks. The hypothesis is that high levels of self-reported sleepiness (KSS 9) and...

Design and analysis of semi-controlled studies

Semi-controlled studies provide a hybrid approach in between controlled experiments and naturalistic driving studies. As in controlled experiments, the researcher can assign participants to groups, select the route and define the tasks, but the...

A comparison of driver sleepiness in the simulator and on the real road

For safety reasons as well as for experimental control, driver sleepiness experiments are often run in simulators. The aim of this study is to compare the development of driver sleepiness in an advanced driving simulator experiment with real road...

Evaluation of methods for the assessment of attention while driving

The ability to assess the current attentional state of the driver is important for many aspects of driving, not least in the field of automation. Knowledge about the driver’s attentional state is necessary for the assessment of the effects of...

Bicyclists‘ speed adaptation strategies when conducting self-paced vs. system-paced...

The increasing prevalence of mobile phone usage while cycling has raised concerns, even though the number of cyclists involved in accidents does not increase at a comparable rate. A reason for this may be how cyclists adapt travelling speed and task...

Evaluation of methods for the assessment of minimum required attention

The empirical methods eye tracking while driving, visual occlusion while driving, think aloud while driving, expert judgement in the laboratory and think aloud while watching video are evaluated for their usefulness to assess driver attention in...

Video-based observer rated sleepiness versus self-reported subjective sleepiness in real...

Observer-rated sleepiness (ORS) based on video recordings of the driver’s face is often used when analysing naturalistic driving data. The aim of this study is to investigate if ORS ratings agree with subjective self-reported sleepiness (SRS).Forty...

Interface design of eco-driving support systems: Truck drivers’ preferences and...

The aim of the study was to investigate the perceived usefulness of various types of in-vehicle feedback and advice on fuel efficient driving. Twenty-four professional truck drivers participated in a driving simulator study. Two eco-driving support...

Bicyclists’ visual strategies when conducting self-paced vs. system-paced smartphone...

Visual distraction among cyclists interacting with their mobile phones is a growing concern. Yet, very little research has actually investigated how cyclists apply visual strategies and adapt task execution depending on the traffic situation. The...

Continuous versus intermittent presentation of visual eco-driving advice

Automatic eco-driving advice has the potential to improve fuel economy and reduce emissions. However, providing eco-driving information to the driver will inevitably draw attention away from the driving task. The objective of this research is to...

Landscape heritage objects' effect on driving: a combined driving simulator and...

According to the literature, landscape (panoramas, heritage objects e.g. landmarks) affects people in various ways. Data are primarily developed by asking people (interviews, photo sessions, focus groups) about their preferences, but to a lesser...

Cognitive workload and visual behavior in elderly drivers with hearing loss

The purpose was to examine eye tracking data and compare visual behavior in individuals with normal hearing (NH) and with moderate hearing loss (HL) during two types of driving conditions: normal driving and driving while performing a secondary...

Experiencing moose and landscape while driving: a simulator and questionnaire study

Animal vehicle collisions (AVC's) have large economic, medical and ecological consequences but have rarely been studied with respect to driver behaviour. The aim of this study was to investigate different AVC-relevant landscape settings (vegetation...

Sleep-related eye symptoms and their potential for identifying driver sleepiness

The majority of individuals appear to have insight into their own sleepiness, but there is some evidence that this does not hold true for all, for example treated patients with obstructive sleep apnea. Identification of sleep-related symptoms may...

Secondary Task Workload Test Bench – 2TB: final report

The main aim of this study was to investigate a selection of commonly used performance indicators (PIs) that have been reported to be sensitive to distraction and workload. More specifically, the PIs were tested for their ability to differentiate...

Simulator validation with respect to driver sleepiness and subjective experiences: final...

In the previous project SleepEYE, which aimed at developing tools for driver sleepiness detection, two experiments were carried out. In the first experiment, 18 drivers conducted two driving sessions on a motorway: one during daytime (alert) and one...

Driver acceptance and performance with LDW and rumble strips assistance in unintentional...

In this ViP project the focus of investigation was whether drivers more readily accept either rumble strips or an in-vehicle lane departure warning system (LDW) in unintentional lane departure situations. The results show that acceptance was high...

Fit-for-duty test for estimation of drivers’ sleepiness level: Eye movements improve the...

Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye...

Crash Barriers and Driver Behavior: A Simulator Study

Objective: The study examines how drivers experience a conventional W-beam guardrail (metal crash barrier) along both sides of narrow versus wider roads (single carriageway with 2 lanes) in terms of stress, feelings, and driving patterns and whether...

A gaze-based driver distraction warning system and its effect on visual behaviour

Driver distraction is a contributing factor to many crashes; therefore, a real-time distraction warning system should have the potential to mitigate or circumvent many of these crashes. The objective of this paper is to investigate the usefulness of...

Effects of electronic billboards on driver distraction.

OBJECTIVE: There is an increase in electronic advertising billboards along major roads, which may cause driver distraction due to the highly conspicuous design of the electronic billboards. Yet limited research on the impact of electronic billboards...

Dangerous use of mobile phones and other communication devices while driving: A toolbox...

The use of mobile phone and similar devices while driving has been a topic of discussion and research for several years. It is now an established fact that driving performance is deteriorated due to distraction but no clear conclusions can yet be...

Why Sweden should not do as everybody else does

Sweden is the only country in Europe that does not outlaw handheld phone use while driving. This puts some political pressure on Sweden. The Swedish Government commissioned VTI to conduct a literature review on the effects of mobile communication on...

Validating speed and road surface realism in VTI driving simulator III

New simulator models concerning vibration, noise and graphics have been designed and implemented in the VTI Simulator III. The objective of this study is to validate this simulator in terms of road surface realism. Twenty-four drivers participated...

Processing of eye/head-tracking data in large-scale naturalistic driving data sets

Driver distraction and driver inattention are frequently recognized as leading causes of crashes and incidents. Despite this fact, there are few methods available for the automatic detection of driver distraction. Eye tracking has come forward as...

The impact of tunnel design and lighting on the performance of attentive and visually...

The crash risk in tunnels is lower than on the open road network, but the consequences of a crash are often severe. Proper tunnel design is one measure to reduce the likelihood of crashes, and the objective of this work is to investigate how driving...

Åtgärder mot trafikfarlig användning av kommunikationsutrustning under körning: en...

This report outlines possible means to reduce the dangerous usage of mobile phones and other communication devices while driving, while at the same time preserve the positive effects. The suggested countermeasures cover several areas and are...

Countermeasures against dangerous use of communication devices while driving –: a toolbox

This report outlines possible means to reduce the dangerous usage of mobile phones and other communication devices while driving. An important aspect of this commission was to demonstrate alternatives to legislation. The suggested countermeasures...

Measuring driver impairments: Sleepiness, distraction, and workload

Snow was falling heavily when Sarah was driving on a slippery road to her cousin’s country cottage. It was dark outside, and the visibility was poor. She had planned to arrive before sunset, but the rental service had made a mistake, and it took...

Can we trust driver behaviour assessment?: Examples from research in simulators and in...

It is very common to compare mean values of driving performance indicators (PI) like mean speed, the standard deviation of lateral position, time headway, mean glance duration, and many more, in order to investigate possible differences between...

Camera-based sleepiness detection: final report of the project SleepEYE

Two literature reviews were conducted in order to identify indicators of driver sleepiness and distraction. Three sleepiness indicators – blink duration, blink frequency and Perclos – were implemented in the camera system.The aims of the study were...

Rumble strips in centre of the lane and the effect on sleepy drivers

The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective...

Mobile telephones and other communication devices and their impact on traffic safety: a...

VTI was commissioned by the Swedish Government to compile relevant research on mobile phone and other communication device usage whilst driving. Thus, a sub-set of those activities that can distract a driver in traffic are treated in the...

Inverkan av elektroniska reklamskyltar på trafiksäkerhet: en studie på E4 i Stockholm

The present report presents four studies that were conducted with the aim to evaluate how electronic billboards (ERS) affect traffic safety. Study 1 is a literature review to examine how billboards impact road safety. The conclusions from the review...

Comparison of eye tracking systems with one and three cameras

When using eye movements to determine the state of a car driver it is important that the eye tracker is robust, unobtrusive, inexpensive and fully automatic. The objectives of this study are to compare the performance of a one-camera system with a...

Review of real-time visual driver distraction detection algorithms

Many incidents and crashes can be attributed to driver distraction, and it is essential to learn how to detectdistraction in order to develop efficient countermeasures. A number of distraction detection algorithms have been developed over the years,...

Detecting sleepiness by Optalert: final report

Many crashes with heavy vehicle can be attributed to driver sleepiness or driving impairment due to sleepiness, and it is important to find methods to predict those situations and counteract this problem. The Optalert fatigue management system...

Räfflor i mitten av körfältet: ett försök i Skaulo

The aim with the study was to evaluate the effects on road user behavior when using milled rumble strips in the centre of the lane on a road 6.5 meters wide. The evaluation included measurements of speed and lateral position. Measurements were done...

Predicting visual distraction using driving performance data

Behavioral variables are often used as performance indicators (PIs) of visual or internal distraction induced by secondary tasks. The objective of this study is to investigate whether visual distraction can be predicted by driving performance PIs in...

Performance of a one-camera and a three-camera system

Driving and operating a vehicle is to a great extent a visual task. In driver behaviour studies it is therefore important to be able to measure where the driver is looking. Today this can be done unobtrusively and remotely in real-time with camera...

The relationship between glance direction and eye tracking quality based on data from a...

It has been shown that distraction is a major factor contributing to road casualties. Detecting and limiting driver impairment could improve road safety. With the introduction of unobtrusive gaze-tracking systems gaze based real-time algorithms can...

Considerations when calculating percent road centre from eye movement data in driver...

Percent road center (PRC) is a performance indicator which is sensitive to driver distraction. The original definition of PRC is based on fixation data extracted from eye movement recordings, but it has also been suggested that PRC can be determined...

Issues related to the driver distraction detection algorithm AttenD

Driver distraction is a contributing factor to many crashes and a real-time distraction warning system has the potential to mitigate or circumvent many of these crashes. The objective of this paper is to thoroughly describe the distraction detection...

Comparison of two eye-gaze based real-time driver distraction detection algorithms in a...

Driver distraction is a field which has received increasing attention in the last years, especially after it became evident that distraction is a major factor contributing to road casualties. Monitoring, detecting and limiting driver distraction...