Memorandum by the Institution of Highways
and Transportation (RTS 38)
ROAD TRAFFIC SPEED
1. Improving road safety is one of the cornerstones
of the IHT. Reducing avoidable death and injury that excessive
or inappropriate speed brings with it is fundamental. Consequently
we welcome the Committee's Inquiry into this important issue.
Types of Speed
2. There are two things upon which we can
all agree. Firstly, the faster you drive, the harder you crash.
Secondly, speeding drivers kill and injure other road users in
avoidable (or, at least, avoidably severe) accidents. But this
does not only relate to excessive speed (exceeding the legal limit)
but also, and often with more serious consequences, inappropriate
speed (driving at a speed that is inappropriate for the prevailing
circumstances, even though it may be within the legal limit).
Accordingly, we believe the scope of the Inquiry should cover
both excessive and inappropriate speed.
Types of Impact
3. Road traffic speed has social, economic
and environmental impacts.
4. Each accident generates substantial costs
in terms of resources, lost production, health care, social benefits
and, of course, in personal pain, grief and suffering. The risks
of accident, injury and death rise with speed, at all speeds.
They rise faster as speed increases. The more severe the consequences
being analysed (ie accident, injury or death), the faster risk
rises with speed.1
5. But accidents and casualties should not
be the only concern. There is a quality of life dimension too.
High speeds create severance, fear, intimidation and perceptions
of danger, particularly when different types of road users mix
in close proximity. It is harder to quantify than accidents but
nevertheless a factor that affects people's daily lives. In terms
of research knowledge the Press Notice mentions the very high
pedestrian casualty rate. This should also refer to cycle casualty
6. Road accidents have been estimated to
cost the country over £16,000 million per year. But road
traffic speed, or more accurately, faster journey times bring
with them economic considerations and some benefits from time
savings. We know that journey time falls with increasing speed,
but falls more slowly as speed increases. Thus there are diminishing
returns from increased speed in terms of journey times. Yet there
are rapidly rising risks associated with increasing speed. Thus,
there is a balance to be struck between the social and economic
considerations and that balance should include the environmental
7. The environmental impacts per vehicle
kilometre travelled depend on speed. Emissions of oxides of nitrogen,
which contribute to acid rain, increase with speed, at all speeds.2
Emissions of particulates and carbon monoxide, which contribute
to respiratory problems, increase with speed at higher speeds,
but at lower speeds they decrease as speed increases.2
8. Catalytic converters have lower levels
of emissions after the first few kilometres of travel from cold,
but emissions of oxides of nitrogen and carbon monoxide still
increase with speed at higher levels.
9. Emissions of carbon dioxide, which are
proportional to fuel consumption and contribute to global warming,
decrease as speed increases at lower levels but increase with
speed at higher speeds (2).
10. Traffic noise (primarily engine and
transmission noise) decreases as speed increases at lower speeds.
However, noise increases roughly as the square of the speed at
higher speeds (at which it consists mainly of tyre noise).
Urban and Rural Considerations
11. Road traffic speed raises different
issues in urban and rural situations. We urge the Committee to
take due account of the different issues and consequences in their
Inquiry. Over the past decade, the proportion of total accidents
and casualties in rural areas has increased, particularly the
most serious accidents where speed is a major contributory factor.
Furthermore, rural roads are expected to carry the brunt of future
traffic growth. The Press Notice refers to the consequences of
illegal and inappropriate speed for urban design. We urge that
the Committee also considers the consequences for rural design
where techniques to manage speed need to be sensitive to local
civic and environmental conditions.
12. Special attention is required concerning
roads between villages. In our Guidelines on Rural Safety Management
(3) we argue for a whole route approach to speed and safety management.
The primary aim is to ensure consistency of perception and design.
The Guidelines also make recommendations concerning the development
of a rural road hierarchy, which are referred to in the Secretary
of State's report to Parliament on the subject, November 2001.
The IHT is holding a major seminar on 12 February 2002 on Rural
Road Speed Management and we do hope the Committee can be represented.
In any event, we would be delighted to report back the key findings
to the Committee in oral evidence.
13. This brief review of the major impacts
arising from road traffic speed demonstrates that, broadly speaking,
all the impacts except journey time argue against the highest
14. This section briefly outlines some important
considerations that the Committee could usefully consider.
15. Choice of speed in the prevailing circumstances
is a matter for the individual motorist. In a "free society"
choice of speed is, rightly or wrongly, seen as an issue of personal
freedom. It is an emotive topic. Thus it is important to present
speed management policy effectively and demonstrate clear grounds
for regulations and limits where selected.
16. However, as far as society's reaction
to speed goes, it could be argued that perceptions are some 15
years behind the drink-drive issue. Something like 95 per cent
of all drivers admit to exceeding speed limits. Thus the climate
of public opinion, and perceptions of risks and impacts are important
17. There is evidence to suggest (4 and
5) that a large proportion of drivers and pedestrians think that
speeds are generally too high. Most drivers see speed as a principle
source of danger and recognise a range of advantages of speeds
being lower. Thus the climate of public opinion may well be favourable
to speed management policies, but more effort is needed to raise
awareness of the risks and impacts, and change behaviour, to the
extent seen in the drink-drive campaign. Affecting behaviour is
the key to success.
18. Road design and classification are important.
In short, speed limits need to match the function of the road
and, broadly speaking, be seen by road users as being about right
for the circumstances. Roads need to look as though motorists
should drive along them at the appropriate speed. This should
be an important aspect of any speed management hierarchy.
19. In the urban context there are useful
lessons to cascade from the Gloucester Safer City project. In
the rural context we strongly urge that a similar demonstration
project be carried out to demonstrate the benefits of a whole
route approach to rural safety management, the main elements of
which are set out in our Guidelines (4).
20. There is a particular gap in knowledge
and practice concerning speed management on high capacity routes.
21. There is no accepted measure of risk
associated with pedestrians. There is no data on pedestrian accidents
per distance walked.
22. There is little, if any, objective way
of analysing accidents in rural villages as they are not identified
in the data where there is no speed limit.
23. Enforcement is one of the so-called
three "E"s of road safetyengineering, enforcement
and education. As such it is an important component of speed management.
However, as police resources are stretched, traffic enforcement
is not as high a priority as some police forces might otherwise
24. As far as speed is concerned, it is
impossible to separate enforcement from the use of speed (or,
more appropriately, safety) cameras. This area of speed management
has come in for substantial criticism and there is undoubtedly
room for better policy presentation. The public has not "bought-into"
the policy or the technique partly based on the perception that
the prime motivator is raising revenue and that cameras are deliberately
inconspicuous. This is not the case, but perceptions count. We
urge the Government to be resilient but to ensure that the policy
is seen to be targeted at casualty reduction, perhaps, in certain
circumstances, in association with additional vehicle actuated/responsive
signs that advise motorists of their speed in advance of a safety
camera. The safety camera is a valuable deterrent. Its use should
be targeted and used flexibly to generate the greatest accident
reductions. Reliable and cost-effective techniques to measure
speed over whole routes, rather than at specific locations, should
be developed and rolled-out more widely to tackle the tendency
for drivers to step on the brakes when they see the camera ahead,
and speed up again as soon as they have passed it.
25. Pedestrian railings were criticised
in the Committee's Inquiry into Walking in Towns and Cities. Barriers
and railings should not be a tool of first resort, but they do
have an important role in appropriate circumstances, particularly
on high speed roads or roads where the traffic environment can
not be "humanised" to the extent that they become unnecessary.
26. We urge that there should be focused
monitoring of road safety investment and outcomes in Local Transport
Plans. In particular, if the Government's road safety targets
are to be achieved, and road traffic speed is a contributory factor,
the implication of the move to the Single Capital Pot for local
authority capital investment will need to be monitored.
27. The Committee could usefully consider
the penalties associated with driving and speeding offences to
determine if they are appropriate and sufficient to act as a deterrent.
28. The Institution of Highways and Transportation
(IHT) represents over 10,000 professionals working in highways
and transportation in the public and private sectors. It promotes
professional excellence as the leading learned society dealing
with urban and regional transport systems and infrastructure at
all stages of the project life cycle. We would be delighted to
present oral evidence and answer questions if the Committee would
find it of value.
29. The key documents dealing with speed
and safety policy more generally are referenced in A Road Safety
Good Practice Guide, DTLR, 2001, and will not be repeated
30. This submission draws on the following
paper by Professor Richard Allsop OBE of University College London,
a member of the IHT's Road Safety Panel:
Allsop R E (1999), Understanding the impacts
of speed, PACTS Conference, London, February 1999.
Director of Technical Affairs
1. Andersson G and Nilsson G (1977), Speed
Management in Sweden, Linköping; Swedish National Road
and Transport Institute VTI.
2. Mitchell C G B (1993), Influencing
speed and its environmental benefitsvehicle design. PACTS
Conference, London, March, 1993.
3. Rural Safety Management (1999), IHT.
4. Kallberg V-P, Allsop R et al (1998).
Recommendations for speed management strategies and policies.
MASTER Deliverable D12.
5. Kallberg V-P, Allsop R et al (1998),
Strategies and tools for speed management on European roads.
European Transport Conference Loughborough, 1998.