Supplementary memorandum by DTLR (TYP
Tim Matthews of the Highways Agency, in his
letter to you of 1 March, suggested that DTLR was better placed
than the Agency to answer your question about the effect on travel
times of a 5 per cent reduction in congestion. I am responding
to that question and I apologise for the delay in doing so.
Results from the Department's National Transport
Model show that, in 2000, the average speed on the Highways Agency's
inter-urban network was 80.6 kilometres/hour (44.7 seconds/kilometre).
With the 10 Year Plan in place, average speeds are forecast to
rise to 81.6 kph (44.1 s/km). Although this change appears small,
you should bear in mind that, without the Plan in place, speeds
in 2010 are forecast to fall to 77.6 kph (46.4 s/km). The Plan
therefore delivers an improvement of 2.3 s/km, not 0.6 s/km.
With the Plan, motorway speeds in 2010 are forecast
to be 54.6 kph in outer conurbations and 101.3 kph in rural areas.
(89.2 kph overall). Without the Plan, the figures are 48.2 kph
in outer conurbations and 96.3 kph in rural areas (83.0 kph overall).
In outer conurbation motorways, the Plan delivers improvements
of 8.7 s/km, whereas in rural areas (where congestion is much
less to begin with) the improvement is only 1.9 s/km.
Dissagregating these figures into peak/off-peak
will require extra computing time, which we are, of course, happy
to undertake. Such figures will show that the gains during the
peak are considerably greater than the overall figures presented
here. I will write again shortly.