DISCUSSION

EMERGENCY BRAKING TESTING

The Effectiveness of the ETBS can be shown by calculating the residual speed of the vehicle if it was not fitted with the system. If the residual vehicle speed is calculated for each of the speeds in Table 5.2 under the test conditions, we get the following:

• When decelerating from 80km/h, the ETBS equipped vehicle would reach 20km/h 5.1 metres before the vehicle without ETBS. The vehicle without ETBS would be still travelling at 35.2km/h.
• When decelerating from 60km/h, the ETBS equipped vehicle would reach 20km/h 1.5 metres before the vehicle without ETBS. The vehicle without ETBS would be still travelling at 25.2km/h.
• When decelerating from 40km/h, the ETBS equipped vehicle would reach 20km/h 0.5 metres before the vehicle without ETBS. The vehicle without ETBS would be still travelling at 21.5 km/h.

WHAT DO THESE SPEED DIFFERENTIALS MEAN IN TERMS OF REDUCTION IN INJURY?

The results obtained by Ashton and Mackay1 (1979) show that in an impact with a pedestrian at a speed of 35km/h (standard vehicle), there is still a possibility of fatal injury occurring to a pedestrian, a 65% chance of serious injury and about 32% chance of slight injury. While at an impact speed of 20 km/h (ETBS equipped vehicle), the injuries are most likely to be slight with only a 10 to 15% risk of being severe.

Similarly the work of Richards2 (2010) shows a 10% risk of fatal injuries and a 60% risk of serious injury for a pedestrian hit at 35 km/h (19.5 mph) for the standard vehicle stopping from 80 km/h. While at an impact speed of 20 km/h (12 mph) for the ETBS equipped vehicle stopping from 80 km/h, the injuries are most likely to be slight with only a 20% risk of being severe. In a pedestrian impact involving braking from speed, the vehicle with ETBS gives a significant reduction in injury risk.

The Emergency Vehicle Driver Training for United States Fire Administration states that “the emergency vehicle driver must possess fine coordination in controlling his vehicle and reacting to traffic problems. He cannot drive faster than traffic permits, nor should he drive faster than his ability to stop in an emergency.

Excessive speed, reckless driving, failing to slow down or obey signals, disregarding traffic rules and regulations, and failing to heed warning signals are often prime factors in such emergency vehicle accidents. It is in this area that the ETBS has the potential to assist the emergency vehicle driver by speeding response times and reducing braking distances.

1. Ashton SJ, Mackay GM (1979) “Some characteristics of the population who suffer trauma as pedestrians when hit by cars and some resulting implications”. Proceedings of the 4th IRCOBI Conference.

2. Richards DC. (2010) “Road Safety Web Publication No. 16: Relationship between Speed and Risk of Fatality: Pedestrians and Car Occupants”, Department of Transport, London.