Category Archives: driving simulator

Can a simulator be used in driving tests?

In a driving test (also known as a driving exam) a person’s ability to drive a motor vehicle is tested. It is required to pass the test in order to obtain a driver’s licence. Usually, a driving test is separated into two parts: a road test, to assess driving ability, and a theory test, to test the knowledge of traffic rules and regulations.

The theory test usually is standardized and the same for all people who apply for the test. This makes the test fair. The situation for the road tests is totally different, however. In some countries the road test is restricted to testing the ability to control the vehicle. This concerns a maneuverability test that consists of driving through a set of traffic cones, reversing around a corner and making emergency stops. In other countries, the test consists of driving in traffic in various situations. The situations to which the student is exposed can differ widely. Some students perform the test in a complex urban traffic environment, while others enter and exit a highway a few times. Also, the interrater reliability is often very low, meaning that some examiners are more strict than others. This situation can make passing a road test look like a lottery.

It is often questionable whether the road test really tests the ability to drive a vehicle. Driving a vehicle entails much more than simple being able to control the vehicle. You have to be able to drive safe as well. You have to be able to anticipate on potentially dangerous situations, recognize road signs and know how to apply the rules of the road.

With a car driving simulator, driving tests can be made more fair. You can use a driving simulator to give every person the same test. This should preferably be a standardized test in which all relevant situations are included. Also, the problem of inter-examiner reliability is solved because the simulator software will rate driving behaviour consistently and apply the same norms for all students.

It will probably be a long way before driving simulators are used to test driving ability and replace the current road tests, but I think it will be a big step forward in terms of fairness and quality.

Differences in quality of driving schools

There are hugh differences in quality of driving schools. It is difficult to pinpoint exactly which factors determine whether a driving school is good or bad. There has been a lot research into factors that determine the quality of driver training, and the most consistent finding is that the amount of practice in relevant driving tasks is a very important factor. Lack of driving experience is probably the most important reason why young drivers fail for their driving exams or are overrepresented in the accident statistics. This would suggest that driving schools with an excellent track record generate more driving experience in their students, although this has not been investigated properly. This finding suggests that it is generally not a very good idea to apply for courses that promise passing the exam within only one week (crash courses). It also suggests that a learner permit where young drivers are supervised by an experienced driver and have to practice a lot while they are only allowed to drive in favourable circumstances (for example only during daylight) is probably a good idea. It has never been proved that supervision by professional instructors results in better drivers or higher pass rates at exams, compared to supervision by parents. All in all, extensive practive before the driver exam is taken appears to be the most important factor.

But it is clear that quality of the driving school is an important factor that affects the choice of a driving school by a learner driver. In most countries it is difficult for a customer to find out which driving school is the best. In the Netherlands, around 7750 driving schools were registered in 2012. All driving instructors have to be licenced and all have followed extensive training to become a registered instructor. In order to apply for your driving test, on average 40 lessons (one hour per lesson) are required in a learner car on public roads. The instructor determines when the learner driver drives good enough to have a good chance to pass for the exam. Still, year after year the average pass ratio for the driver test (first time) is 50%.

In the Netherlands the pass ratios of driving schools are publicly available via the website of the examination institute (CBR). These numbers are available to the public and are used by learner drivers to choose a driving school. A number of driving schools have consistent high scores while other driving school consistently perform poorly on pass ratio. What is a good driving school is a matter of definition ofcourse, but lets define a good driving school as a driving school where more than 75% of all students pass the first time they do the driving test. Over a large sample of driving schools, around 12,5% of all driving schools can be qualified as ‘good’, according to this definition. If we define a poor driving school as one where only 25% of all students pass for their exam the first time, then around 17,5% of all driving schools can be considered ‘poor’. 70% of all driving schools are then ‘average’.

The ‘good’ driving schools generally attract a lot of learner drivers. They do well economically, while the ‘poor’ driving schools struggle to survive, in general, in this very competitive market. Ofcourse there will always be a normal distribution of pass ratios where there will be relatively good and relative poor driving schools, but a pass percentage lower than 25% is low according to Dutch standards, where a pass ratio of 50% is considered ‘normal’. These driving schools can benefit strongly by using a car simulator to increase the level of practice and task automation in their students. This increases the quality of driver training for these driving schools because the simulator curriculum promotes task automation and extensive practive in relevant driving tasks. It is expected that this will increase the pass ratio and thus attract more customers.

Driving simulator applications

Car driving simulators are used for various purposes. The first thing that comes to mind when thinking about driving simulators is driver training. Most simulators are used for initial driver training in driving schools. See for more information an article about driving schools and one about the suitability of a driving simulator for driver tests. Other driving training applications are:

  • simulators for police training. Police training on public roads is often difficult because of regulations concerning the use of optical and sound signals (siren and flash light). Simulators can be very useful then because they allow policemen to practice driving with police siren. Other drivers often respond unexpectedly when a policecar approaches fast and with sound signals.
  • simulators for emergency services. Ambulance and fire engine drivers can also practice in a simulator in the use of optical and sound signals. A simulator offers excellent opportunities to practice driving in traffic and apply the rules for ‘priority vehicles’, while learning how to cope with other traffic.
  • training of hazard perception. Inexperienced drivers are often deficient in their recognition of hazards. A simulator can offer special training scenarios of unexpected situations that don’t occur often in the real world.

Apart from driver training, other driving simulator applications are:


Distracted driving simulator

Distracted driving is, next to DUI (driving under the influence), one of the main causes of car driving accidents. Distracted driving is the act of driving while engaged in other activities—such as looking after children, texting, talking on the phone or to a passenger, eating, or reading—that take the driver’s attention away from the road. All distractions compromise the safety of the driver, passengers, bystanders and those in other vehicles (definition from Wikipedia). Distracted driving is now considered as an epidemic: only in the US, in 2012 more than 3000 were killed in distracted driving crashes.

Driving a vehicle requires a considerable amount of attention. This is expecially so for young, inexperienced, drivers, who still need controlled attention while driving a car. Sharing their limited attentional resources with other tasks, such as texting or using a cell phone, goes at the expense of driving performance. Expecially when the eyes are taken off the road for more than 3 seconds will result in severly increased accident risk.

Young drivers typically overestimate their driving skils and their ‘multitasking’ ability. They often think they can do two things simultaneously: driving and texting. However, multitasking is only possible when both tasks don’t require controlled attentional resources, such as eating while walking. Texting definitely requires attentional resources and driving a car most definitely requires controlled attention for young drivers. This is the reason that distraction affects young drivers stronger compared to experienced drivers.

In order to make young drivers more aware of the effects of distracted driving on accident risk, a test drive in a driving simulator can be a convincing eye opener.

Clinical applications in a driving simulator

Car driving simulators are particularly known for their use in driver training, police training, and also for their application in DUI simulation and demonstrating the effects of driver distraction. However, a driving simulator can be also be succesfully applied in a number of clinical applications, especially fear of driving, evaluation of fitness to drive and rehabilitation in a clinic.

Treatment of fear of driving

For clinical psychologist who treat various anxieties and phobias and use exposure therapy to treat their clients, a simulator can be an instrument in the treatment of fear of driving or driving phobia. Exposure therapy involves the exposure of the patient to the feared object or context without any danger, in order to overcome their anxiety. Giving exposure therapy to people with fear of driving in a real car in traffic is difficult in practice: the real risk of accidents is high and always involves a licenced driver instructor as well as a therapist which makes the therapy sessions expensive and difficult to arrange. Also, the environment is in real car in the real word is impossible to control, which is definitely not what a therapist wants. Exposure therapy in a driving simulator to treat fear of driving gives the therapist a controlled virtual environment in which the client is exposed to the anxiety inducing situations without any danger. Virtual reality is used more often to treat phobias.

Evaluation of fitness to drive

Fitness to drive for older drivers and drivers with neurological disorders, after CVA or sleep disorders is typically done by general practitioners using paper and pencil tests, blood samples and eye measurements. However, a simulator can make the fitness to drive test more ecologically valid: it resembles the driving tasks and testing can be done in a structured environment with the same test for all clients. While a simulator may someties be less suitable for the assessment of driving behaviour in older people, because of the increased risk of simulator or cyber sickness in this population, the incidence of simulator sickness can be reduced substantially, when a number of precautions are being taken in the design of the tests. Simulator tests can be a valuable addition to the set of diagnostic instruments to evaluate fitness to drive.

A special branch of clinical applications is the use in a test battery of neuropsychological tests. In a research simulator setup, clinical tests can be developed, for example to evaluate if patients with sleeping disorders are at risk of falling asleep while driving.

Driver rehabilitation and occupational therapy

A driving simulator program can offer a number of practice to people in occupational therapy for the purpose of driver rehabilitation. Especially, turning at intersections, reacting to unexpected events and negotiating fourway intersections and roundabouts can be trained in this group. The goal of driver rehabilitation is to aid individuals with disabilities or age-related impairments maintain independent driving and transportation. This maybe done through the use of specialized mobility equipment and training.


Virtual reality in a car driving simulator

In a VR system, a computer generated world is displayed by means of a helmet mounted display (HMD). A headtracker measures the position of the head and the direction the subject is looking at. The images are then presented to both eyes separately, from the viewpoint of the head in the direction the head is facing. Since images are presented to both eyes stereoscopically, the subject experiences depth which enhances the experience. Since the eyes are covered in most VR systems, the subject is unable to see the actual surroundings: only the virtual world is experienced and this greatly enhances immersion.

VR systems have been around since the seventies of the 20th century. The availability to the general public has been low because of the high cost and technical insufficiencies, for example, narrow field of view, inaccurate and slow headtracking that increases the lag between headmovements and graphical updates, and poor resolution. The more expensive systems are used in military training. However, the VR technology has not become popular in games or simulators. An important reason for that, apart from the cost, is the cybersickness that often occurs while using a HMD.

The Oculus Rift is the most recent development in VR that promises a larger field of view, high resolution, fast headtracking and less cybersickness for a very affordable price. It is tempting to use a quality low cost VR system like that in a driving simulator for driver training. It would reduce the cost of the simulator because a complex and expensive projection system is not required. You would have a very natural 3D vision with real stereoscopy. The experience of realism would be higher compare to regular driving simulators. Driver training in a VR simulator could potentially be more attractive for young learner drivers than traditional driver training because of the experience it can provide.

A regular driving simulator is similar to a Virtual Reality system, except for the helmet mounted displays (HMD’s) and head tracking. In both types of system, a computer generated world is presented to the driver and the driver interact with this world. In the case of a driving simulator, you drive through the computer generated world as if you are seated in a real car and you interact with other traffic participants and the road infrastructure in a very realistic but also safe way. A driving simulator is perfect for young inexperienced drivers. They hardly ever experience simulator sickness.

Simulator sickness is similar to the cybersickness experienced in VR systems, but it differs in some respects as well. Simulator sickness is very much related to the absense of motion which causes a mismatch between what you see and what you (expect to) feel. Since only experienced drivers have learned the experience of motions that occur, for example during lateral and longitudinal accelerations, they experience a mismatch between what they see and the lack of motions (in a fixed base simulator). This increases the risk of simulator sickness in older and more experienced drivers, while the risk is very low in young and inexperienced drivers. Simulator sickness also increases with higher immersion and with projections over a larger horizontal field of view. For example, a three-display (120 degrees horizontal field of view) simulator results in a higher incidence of simulator sickness compared to a simple one-display system. Also, a system with 180 degrees of larger projection screens gives a higher risk of simulator sickness compared to 23 inch monitors. In a regular driving simulator, the rendering of the graphics is static: on the left, middle and right displays the images are always from the perspective of the position of the head facing forward. So, to see what is left of you, you look to the left display. If you want to see what is in front of the car, you look at the middle display and if you want to look to the right, you check the right display. In other words, your ego reference is pretty much fixed. You sit in a virtual car and as the vehicle moves through the world, you move with it and your absolute position in the vehicle is fixed.

In a VR system this can be very confusing. There’s the motion of the vehicle which results in a different position and viewing direction in the virtual world, and there’s also the motion of the head which results in a different position and viewing direction in the virtual world. My point is that these two motions and directions are very difficulty to unravel by the brain in a VR system.

We have done tests with VR systems connected to the driving simulator, most recently with the Vuzix Wrap 1200VR, and we found consistently:

  • driving in a VR system results in cybersickness very quickly, especially when you look around (left and right) while the car is driving. Especially the headaches can be quite pervasive.
  • driving in a VR system is very hard, especially steering is difficult. For example, when you look to the left while you are driving, there’s a strong tendency, which is almost impossible to suppress, to steer to the left as well. So, your steering follows the direction your head turns and this is a persistent effect that makes driving difficult. It’s very difficult to stay in your lane or on the road.

Maybe these effects will not occur in a sophisticated system as the Oculus Rift. However, I doubt that, because the effects are so overwhelming.

Form my experience I would say that, for driving, the HMD as used in VR is not very well suited, because of the risk of cybersickness that comes with the use of HMD’s and because of the difficulty of the brain to separate the effects of vehicle movement and head movements:

  • the vehicle moves through the world, controlled by the steering wheel and pedals of the driver.
  • the driver looks around in the environment by turning the head (head tracking)

These two types of motions in combination give a high risk of cybersickness in a VR system and make steering very difficult. The brain is not very well able to distinguish these movements. It would be interesting to study these phenomena in more detail and to see if and how these problems can be solved. Maybe these effects are not so pervasive in a FPS game, where you ‘walk’ slowly and use other means to move forward (instead of a steering wheel and pedals). In the mean time, I seriously doubt if VR is suitable for driver training in a driving simulator.