Safe Speed Forums

Who can forget the TRRL’s 1967 report on the ‘experimental’ 70mph speed limit imposed by the hapless Tom Fraser and endorsed by non-driving Barbara Castle?

The statistics were worthless. Proposals to make one carriageway of the M1 subject to the limit and the other not, to rule out statistical anomalies, were rejected because they might not have come up with the right answer. As it was, Lord Chesham, chairman of the RAC, said of the TRRL’s report on the four-month experiment: "Never have so many statistics been compared with so many variable yardsticks."

Only comparisons in favour of the limit were used. "As well as being given some curious figures on public opinion, we are told that casualties were fewer than ‘would have been expected’. This devalues the report from the realm of the scientific to one of prophecy and guesswork," said Lord Chesham. The TRRL admitted: "The number of motorway accidents and casualties available for study, even over several years, is relatively small and often inadequate for the detailed studies necessary to reach definite conclusions."

Casualty rates had been falling for six years because the proportion of motorcycles, with high accident rates, had been coming down.

"The numbers killed or seriously injured as a proportion of total casualties varied between 38% and 57% between 1960 and 1965. During the trial period it was 53%." So it was well within the five-year range. A 10% reduction in accidents on 73 miles of motorways fitted precisely with the trend.

Accident rates on all roads had fallen. There was no demonstrable improvement on non-motorways, since hardly any traffic on them exceeded 70mph.

Mrs Castle’s response was to reduce the limit to 60mph. The Roundheads had won.