I have no wish to become involved with "The Progress Report", but I think
those who have been circulated the US Professor's article should have
chance to see this GB Professor's view of the matter
SPEED MANAGEMENT: WHY, HOW. AND THE ROLE OF SPEED LIMITS AND THEIR
ENFORCEMENT?
(Text that forms part of other contributions by the author on this topic;
December 2004)
Richard E Allsop, Centre for Transport Studies, University College London
1 Why speed management and why this usually means moderating speed
Speed brings great benefits in the form of shorter travel times for people
and goods (and sometimes enhancement of the experience of travel) at
substantial cost, especially in terms of accidental death, injury and damage.
We all share in the benefits from speed (even those who rarely or never use
a private vehicle) and we all bear some share of the costs. The benefits
from speed are probably neither more nor less fairly shared across society
than many other kinds of welfare - but the sharing of the costs in terms of
accidents is unfair in two distinctive ways:
· many of the costs are borne by those who do not
benefit most directly from speed, notably those who walk and cycle most; and
· massively disproportionate costs are borne by the
minority who are killed or seriously injured in accidents and by their
close associates.
Prevailing speeds are determined by the choices made by drivers and riders
on each stretch of road as they find it. They get much of the benefit of
higher speed immediately for themselves and their associates in terms of
earlier arrival, and possibly the pleasure of going faster. They do bear
some of the cost themselves (mainly increased running costs and risk to
themselves and their associates) but they are known to underperceive these
costs. They do not themselves bear any of the human costs of accidents to
others, or much of the resulting damage to the environment. For these
reasons, there is a tendency inherent in the road traffic system for all of
us to go faster than is good for ourselves or society.
All this means that responsible government of any party must seek to
influence speed, and in many respects to moderate it, and this means
influencing the choices not just of a less responsible minority, but of all
of us as users of motor vehicles, even those of us who may be tempted to
think of ourselves as the most responsible, even altruistic, of
citizens. We are all liable to drive or ride at speeds inappropriate to
the circumstances, and the ultimate aim of speed management is to achieve
appropriate speeds by all drivers and riders in all circumstances.
2 How speed can be managed
Technology is already beginning to offer the long term prospect of
achieving this ultimate aim of speed management, without unnecessary
restriction upon the more capable drivers or riders of the best equipped
vehicles, by means of an intelligent on-board speed regulator. This would
limit the drivers or riders choice of speed at any instant by imposing an
appropriate maximum in accordance with the prevailing local road
environment, the capability and condition of the vehicle, and the current
level of performance of the driver or rider. But this is looking ahead
many years, and even all but the first steps towards it are some years away.
In the meantime, the main ways of managing speed are to influence
driversand ridersindividual choices by:
· education, training and public information education
about the factors that determine what speed is appropriate, training in
judging appropriate speed while driving or riding and controlling the
vehicle to achieve that speed, and public information to inform education
and maintain awareness in the educated;
· adapting the layout and appearance of the roads so
that on each length of road the speed that looks and feels appropriate to
most drivers and riders is indeed appropriate in the circumstances;
adapting the capability of vehicles so that speeds
beyond the range that is acceptable on public roads are no longer available
to people driving or riding there; and
· using traffic law to regulate driversand riderschoice
of speed for the time being mainly by posted speed limits that apply at all
times to the relevant stretches of road (though limits that differ
according to time of day or traffic conditions are beginning to be used).
The rest of this contribution is concerned with the fourth the role of
speed limits and their enforcement in speed management.
3 The role of speed limits and their enforcement
Imposing a speed limit on a stretch of road does not address the aim of
achieving appropriate speeds directly. It does so indirectly by setting a
maximum permitted speed, in the reasonable expectation that speeds chosen
having regard to the imposed limit are more likely to be appropriate than
would be the case if the limit were higher (or if there were no limit at
all, as was the case on many roads in Britain until 1965). Where there is
a speed limit, speed higher than the limit is described as excess speed,
and it is driving with excess speed that constitutes an offence. Driving
with inappropriate speed within the limit constitutes an offence only if
the speed is so inappropriate as to amount to careless, inconsiderate or
dangerous driving within the meaning of the Road Traffic Act 1991.
The relationship between excess speed, as defined and addressed by imposing
a speed limit, and inappropriate speed, which speed management ultimately
seeks to address, may be illustrated by the following table, which shows
the resulting four possibilities in respect of the speed chosen by a driver
or rider in given circumstances.
Speed within the limit
Appropriate speed No problem
Inappropriate speed Not addressed by the limit
Speed above the limit (excess speed)
Appropriate speed Law nevertheless requires speed to be reduced for
the common good
Inappropriate speed Addressed by the limit to the extent that bringing
speed below limit makes it less inappropriate
A speed limit could be a completely effective means of speed management
without requiring anyone to travel more slowly than is appropriate in the
circumstances only if all speeds fell in the upper left or lower right hand
cells of the table and all drivers and riders complied with the
limit. This will clearly never be the case, but extent of approximation
to it may be a useful criterion in judging how reasonable an existing or
proposed limit is for a given stretch of road and its traffic. In other
words, a reasonable limit is one such that speeds below it are appropriate
and speeds much above it are inappropriate for most drivers and riders in
most circumstances, so that not too many are denied the right to travel at
higher but nevertheless appropriate speeds, and not too many speeds within
the limit are nevertheless inappropriate though there will always be some
of these, notably when weather or other conditions call for greater caution
than is usual for that stretch of road.
Clearly then, speed limits cannot address all kinds of inappropriate speed,
but this fact is no reason for failing to use them to full effect to deal
with the kinds of inappropriate speed that they do address namely speeds
that are usually inappropriately high for the stretch of road concerned.
If speed limits are to be effective and respect for them as traffic law is
to be maintained (or, where it has been lost, regained), they need either
to be largely self-enforcing (like 20 miles/h limits made so by road
layout), or perceived to be enforced.
According to the principles set out in the North Report (Department of
Transport and The Home Office 1988), enforcement should be
proportionate: it should bear hard upon the blatantly irresponsible
offender, whilst responding to occasional infringements by basically
law-abiding drivers with penalties that they are able to see as sharp but
justified reminders keep their driving up to the mark.
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