Policy instruments (3) - Transport Policy and Planning in Great Britain - page 229

Table 14.1 Recommended speed limits for single-carriageway roads in rural areas* (source: Adapted
from DfT Circular 01/2006 Appendix D)

Speed limit
(mph)

Roads with predominant traffic flow
function

Roads with important access or recreation
function

60 Most high-quality strategic A and B

roads
Accident threshold below 35 injury
accidents per 100m vehicle km**

Only for best C and unclassified roads
with a mixed (partial traffic flow)
function
In the longer term should be assessed
against upper-tier criteria

50 Lower-quality A and B roads with

relatively high number of bends,
junctions or accesses
Accident threshold above 35 injury
accidents per 100m vehicle km at
higher speeds**
Also for consideration where mean
speeds are below 50 mph

Lower-quality C and unclassified roads
with a mixed function where there
are a relatively high number of bends,
junctions or accesses
Accident threshold below 60 injury
accidents per 100m vehicle km**

40 Roads with high number of bends,

junctions or accesses, substantial
development
Where there are strong environmental
or landscape factors or presence of
vulnerable road users

Roads with predominantly local, access
or recreational function, or if part of
a recommended route for vulnerable
road users
Accident threshold above 60 injury
accidents per 100m vehicle km**

30 The norm in villages

* Limits to which traffic authorities are encouraged to move over a period of time, subject to their
meeting local needs and considerations.
** When the assessment framework (Appendix E) is being used

Since 1991 police authorities have been able to use photographic evidence
uncorroborated by a police officer to bring charges against motorists exceeding the
speed limit. The subsequent introduction of speed cameras has provoked prolonged,
often hysterical coverage in the national press. Evaluation of the first three years of
a national safety camera programme begun in 2000 indicated that the number of
vehicles exceeding the speed limit at over 200 fixed camera sites had dropped by 71%
(DfT 2004g). At all 2,300 sites monitored there was a 33% reduction in personal
injury collisions representing 870 fewer KSI (killed or seriously injured) per year.
However although the general impact of cameras in reducing speeds and collisions
in their vicinity has been demonstrated, the selectivity employed in choice of sites
and other factors makes assessment of their overall effectiveness difficult to determine
(LTT 405 and 434).

14.7 Traffic calming and street management
'Traffic calming' is a term used to refer to a collection of mainly engineering techniques
which alter the character or appearance of the highway and have the effect of reducing
the speed of motor vehicles. These techniques are typically employed to improve safety
amongst vulnerable road users, sometimes in combination with local reductions in
the speed limit as mentioned in the previous section. They may also be used as part of
schemes to discourage through movement by all or certain classes of traffic on minor
roads (i.e. to deter 'rat-running') and thereby add to the quality of the local environment.