to carry out a broad survey of potentially effective road safety measures. The term potentially effective is used deliberately. It denotes any safety measure that there is reason to believe will reduce the number of accidents or the severity of injuries.
The term “potentially” is used in order to include new safety measures in the screening process. If a safety measure is new, in the sense that it has not been used before, its effects on safety cannot be known on the basis of evaluation studies in the traditional sense of the term. This applies to several applications of intelligent transport system technology. It is, for example, technically feasible to introduce a speed governor in all motor vehicles that makes it impossible to drive faster than the speed limit. The effects of such a system on accidents are so far not known, but possible effects on speed are known. The effects on speed give reason to believe that such a system would be effective in reducing the number and severity of accidents. The reason for believing so, is based on general knowledge about the relationship between speed and accidents.
The process of screening of potentially effective road safety measures for
inclusion into a formal assessment of their safety potential, cost-effectiveness and benefit-cost ratio is carried out in two stages:
1 The first stage is to prepare a list of road safety measures that is as exhaustive as possible. An exhaustive lists includes all known measures that have
improving road safety as one of their objectives.
2 The second stage is to screen these measures for inclusion in a formal
assessment of their safety potentials, cost-effectiveness and benefit-cost ratio by means of a set of screening criteria. These criteria are formulated below.
A broad survey of road safety measures is presented in the Traffic Safety
Handbook (Elvik, Mysen and Vaa 1997). The measures covered by this book has been taken as the basis for preparing an exhaustive list of road safety measures.
The Traffic Safety Handbook covers 124 measures. In order to make sure that all potentially effective road safety measures are included, a few measures not explicitly described in the book have been added. The measures that have been added include:
A Vision Zero speed limits
This measure includes introducing Vision Zero speed limits to the road system, but without altering the layout of the roads. It is not assumed that there will be perfect compliance with the new speed limits. It is assumed that mean speed will correspond to the speed limit, which implies a compliance of about 50%. This is
virtually the same as the current compliance with speed limits in Sweden. A ten fold increase in police enforcement has been assumed. A reclassification of all public roads, as indicated in point B below, will serve as the basis for setting new speed limits.
B Reclassification and reconstruction of roads according to Vision Zero Vision Zero implies certain standards for the design of roads. This measure comprises a reclassification of all public roads in Sweden according to the classification system developed as part of Vision Zero, and reconstructing the roads that need reconstruction in order to meet the designs standards developed within the framework of Vision Zero. More specifically, the following changes are assumed to be implemented:
- All motor traffic roads (370 km) will be reconstructed to motorways.
- 280 km of national road with AADT > 8,000 and speed limit 90 or 110 km/h will be reconstructed to 13m roads with a wire median guard rail.
- Wire median guard rail will be provided on 3,500 km of road with a width of 13 m and a speed limit of 90 or 110 km/h.
- 13,600 km of urban road with low traffic volume will be reconstructed according to the design principles for 30 km streets in Vision Zero.
- 9,000 km of urban road with moderate to large traffic volume will be reconstructed according to the design principles for 50/30 streets in Vision Zero (comparable to environmentally adapted through roads).
- 9,000 km of urban access roads with very low traffic volume will be
reconstructed according to the design principles for walking speed streets in Vision Zero.
C New safety standards for motor vehicles
The following new safety standards for motor vehicles have been included in the survey of potentially effective safety measures:
- Requiring self-levelling headlamp systems for new cars from a certain date (retrofitting older cars with this kind of system is not realistic).
- Requiring a seat belt reminder in new cars from a certain date. This a device that gives a warning signal if a seat is occupied and the seat belt is not fastened.
- Requiring an ignition interlock system for seat belts in all new cars from a certain date.
- Introducing new requirements for front design and bumpers on light cars, in order to reduce injuries to pedestrians who are struck by cars (Lawrence, Hardy and Lowne 1993).
- Requiring an energy absorbing structure in the front of heavy cars, in order to reduce the severity of injuries in head on crashes (Riley, Farwell and Burgess 1987, Jones 1987).
D Integrated application of intelligent transport systems technology
The following applications of intelligent transport systems technology have been considered:
- Requiring an automatic accident warning device on all new cars from a
certain date. This is a device that automatically sends a signal to an emergency warning centre when the car is involved in an accident where the airbag is deployed. The car can then be located more quickly by means of, for example, Global Positioning Systems (GPS).
- Requiring a crash data recorder in all new cars from a certain date. This is a small computer that records, for example, braking, steering wheel movements, and the use of direction indicators during the last few seconds before an accident. Information is deleted continuously and stored only in case an accident occurs (Wouters and Bos 1997).
- Requiring an ignition interlock device in the car to detect whether the driver is drunk. The device could take the form of a breathalyser unit, into which the driver would be required to blow in order to be able to switch on the ignition (Glad 1996).
- Requiring intelligent cruise control on new cars from a certain date. An intelligent cruise control device would warn the driver if the forward distance to other vehicles becomes too short.
- Requiring an intelligent speed adaptation system in cars. Such a system would probably have to be fitted in all cars from a certain date. Different designs of the system can be imagined. As a means of driver support, the system would give a warning if the speed limit is exceeded, but not otherwise act to prevent speed limit violations. As a fully integrated control system, the system would overrule driver attempts to exceed the speed limit, by means of a speed governor.
It will be assumed that these applications can be introduced both on an individual basis and jointly as an integrated application of all systems.
E Reforming driver education
Plans have been made to reform the system of driver education and training in Sweden for private cars (Grummas Granström 1998). Although not all details of these plan are ready, it is assumed that a new system will contain one or several of the following elements:
- It will be possible to start driver training at the age of 16 (as today), but the licensing age remains 18.
- A minimum number of kilometres of driving will be required before the driving test can be taken.
- A graduated training system will be introduced. The driving license itself will, however, not be graduated.
- Possibly some special regulations for novice drivers, for example a zero BAC limit.
- Possibly a system rewarding accident free driving, for example the type of insurance scheme introduced by Gjensidige in Norway (Vaaje 1991).
F Vehicle impoundment for drinking and driving
The possibility of using vehicle impoundment to prevent unlicensed driving has been included, based on recent experience in the United States (DeYoung 1999).
5.2 Criteria for Inclusion of Measures in a Formal Assessment of