Vehicle Condition

Condition of Vehicles involved in accidents between 1996 and 2001

Condition of vehicles involved in acidents between 1996 and 2001

Noted Trends

*Primary Trend:

*.Poor tyre maintenance

*Secondary trends:

*.Extensively worn tyre treads and friction material

*.Body badly rusted, extensively worn tyres, brakes and suspension/steering

*.Tyres that do not conform to RTA 29/1998

*Extensively worn tyres, brakes and suspension/steering.

*Dangerous Procedures Noted

by Experts

*brake tubing cut off and clamped;

*brake shoes removed;

*mechanical brake disconnected;

*brake calipers secured with wire;

*vicegrip used as a steering device; and *over inflated tyres as a means to save on fuel.

Unroadworthy vehicles with questionable CRWs involved in accidents between

1996 and 2001

CRW = Certificate of Roadworthiness

Recommendations: Vehicle Maintenance

 The vehicle industry as a whole would have to be part of any reformation attempt.

 The importance of preventative maintenance should be mediated alongside all other pertinent road safety messages, such as "don't drink and drive" or "speed kills."

 Maintenance role players, such as mechanics or tyre dealers, form perhaps the most important relationship with the vehicle owner.

Driver condition

Driving while either intoxicated or drunk is dangerous and drivers with high blood alcohol content (BAC) are at increased risk of car accidents, highway injuries and vehicular deaths

Alcohol is estimated to be a factor in 20-30% of all accidents.(1) In a review of English-language literature over the past 45 years, Hingson and Howland established that:

o 13-37% of non-fatal falls

o 21-47% of drownings

o 9-86% of burn deaths

are alcohol-related. (2)

Also alcohol-related are:

o 25% of accidents at work (3)

o 14% of all road accident deaths (4)

o 30% accidents involving pedestrians. (5)

Honkanen points out that the alcohol consumption patterns of a population are reflected in injury patterns. Injuries among the population groups who consume most (e.g. non-professional men of working age) are most likely to be alcohol-related; so are injuries at certain times (nights, weekends) and in certain places (restaurants and streets).

Accidents of different conditions

Wet and rainy conditions impact driver, vehicle, and roadway. These effects cause a reduction in speed or density (car-following headway) or both which, in turn, cause a reduction in highway capacity. This paper is a synthesis of 26 studies relating wet conditions to speed and capacity.

If the results from all reviewed studies after 1980 with original data from freeways are averaged assuming equal weights, then, the average speed reduction is 4.7 mph in light rain (11 studies) -

HCM2000 suggests 6.0 mph which is similar to FHWA's 10% reduction - and 19.6 mph in heavy rain (2 studies) - HCM2000 suggests 12.0 mph which is higher than FHWA's 16% reduction. The average capacity reduction is 8.4% in light rain (7 studies) and 20.0% in heavy rain (1 study).

The impact of rainy conditions on highway capacity is important. Much additional research is needed for reducing the wide variance of observations in past studies. A methodology is needed for capacity and LOS analysis of freeways, intersections and arterials that accounts for wet conditions as part of typical conditions.

EXPECTED EFFECTS OF RAIN ON PREVAILING CONDITIONS

Light intensity, rain, fog, ice, and snow are significant for highway capacity . The

main impedance factors due to rain are :

* The presence of a water film on the surface of the pavement.

* Reduced visibility and light scattering.

* Rain drops, spray and road grime on vehicle windscreens.

Rain affects roadways, vehicles and drivers. The main effects of rain on roadways are

the reduction of friction between tire tread and road surface, and the reduction of pavement skid resistance. Water film thickness can vary from damp or visibly wet to a depth of several millimeters. Reduction of pavement skid resistance is a combined result of factors such as the thickness of water film on the surface, pavement texture, tire

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