Sleep-related vehicle accidents (No.22)

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CHAPTER 3
M5 Junctions 5-8 Worcestershire

SUMMARY

For the two-year period commencing 1 January 1997 we analysed all road traffic accident (RTA) records held by West Mercia Constabulary for the portion of M5 between Junctions 5 and 8, in Worcestershire. This 18.7 mile section is illuminated.

There were 108 RTAs involving slight injury, serious injury, or death, to which West Mercia Police were summoned. Sixteen were probable sleep-related vehicle accidents (SRVAs), and six were possible SRVAs, making 22 in all and comprising 20% of the total RTAs. Although only 5% of total daily traffic flow occurs during late night/early morning hours, almost one third of these SRVAs happened then.

About half of these SRVAs were caused by cars. SRVAs were about twice as likely to result in death or serious injury compared with other RTAs on this road. Most (82%) of the drivers were men, and half were under 31 years of age. About half the drivers came from skilled occupations (manual). About one third of these accidents occurred on a Saturday.

INTRODUCTION

We carried out a comprehensive data collection and analysis of road accident records for the M5 (Junctions 5-8) held by West Mercia Constabulary, for the two-year period 1 January 1997 to 31 December 1998.

We were only concerned with accidents which involved injury; that is, fatal injury, serious injury or slight injury. The source of our data was Accident Report Forms completed by the Police Officer attending the scene of an accident.

The documentation with the Accident Report Forms examined for this Road Audit included witness statements (with statements of the driver deemed responsible for the cause of the accident), and other evidence such as tachographs, photographs and correspondence relating to the RTA.

ROAD CHARACTERISTICS

This 18.7 miles of motorway is policed by West Mercia Constabulary. It stretches from Junction 5 at Wychbold, approximately two miles north east of Droitwich, to Junction 8, just south of Strensham Services, where the M50 joins the M5.

Southwards from Junction 5, the motorway is straight for a short distance and then bends around the eastern outskirts of Droitwich. It continues through rural land for approximately 2.8 miles, skirts to the east of Worcester, and then continues straight, on a due south east gentle curve, through rural land for approximately 8.4 miles to Junction 8.

This section of the M5 is lit throughout the entire stretch. Between Junctions 6 and 8 this comprises high pressure sodium cut off lanterns (white light). Between Junctions 5 and 6 it is low pressure SOX lighting (orange light). This is to be upgraded to the higher pressure sodium lighting.

The road surface is of rolled asphalt. The width of both carriageways is approximately 36 feet. Each is separated into three equal width lanes. The main carriageways are bordered on either side by reflective rumble strips, plus the usual red/yellow reflective cats-eyes. There are emergency hard shoulders, approximately 11 feet wide, and two feet marginal strips. In parts, there is a grass verge varying in width descending to a drainage gully. A central reservation with a safety fence separates northbound and southbound traffic. Emergency phones are located on both carriageways at approximately one mile intervals.

The M5 motorway is subject to the national speed limit for motorways, 70 mph. However, goods vehicles over 7.5 tonnes maximum laden weight are subject to a maximum speed limit of 60 mph. Legislation requires that speed limiters are set no higher than 85 km/h (53 mph). Powered speed should not exceed 90 km/h (56 mph).

Services

Northbound and southbound services are at Strensham, just north of Junction 8, the southerly point of this Road Audit. These facilities are open 24 hours, have accommodation available and HGV overnight parking.

Northbound, the next motorway service area is at Frankley, Birmingham, just south of Junction 3, approximately 30 miles from Strensham Services. Southbound, the next motorway service area is just north of Junction 14 (Michaelwood), approximately 40 miles south of Strensham and nine miles north of the M4 Junction, Bristol.

RESULTS

During this two-year period, West Mercia Police were called to 108 RTAs involving injury or death on the main carriageways of the M5 between Junctions 5 and 8.

  • 57.4% (62) of the 108 RTAs were northbound; 41.7% (45) were southbound (the direction was unknown for one RTA)
  • 20.4% (22) of the 108 RTAs were SRVAs; 72.7% (16) of these were probable; 27.3% (6) possible
  • Of these SRVAs, 54.5% (12) were northbound and 45.5% (10) were southbound. 75% (9) of the 12 northbound SRVAs were probable, and 25% (3) possible. 70% (7) of the 10 southbound SRVAs were probable and 30% (3) of the 10 southbound SRVAs were possible; this gives rates of 0.6 SRVAs per mile northbound, and 0.5 per mile southbound.

Severity of RTAs and SRVAs

Table 3.1: Severity of RTAs and SRVAs, M5 1997/1998

Severity

RTAs (%)

Possible or Probable SRVAs (%)

Fatal

3 (2.8%)

1 (4.6%)

Serious Injury

27 (25%)

10 (45.4%)

Slight Injury

77 (71.3%)

11 (50%)

Unknown Injury

1 (0.9%)

 

Total No. of RTAs/SRVAs

108 (100%)

22 (100%)

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