Travel in London Travel in London

4. Performance of the transport networks
Table 4.11
Area and
time period
Central AM
peak
Central
inter-peak
Central PM
peak
Inner AM
peak
Inner interpeak
Inner PM
peak
Outer AM
peak
Outer interpeak
Outer PM
peak
Average vehicle delay (minutes per kilometre) by functional sector of
London. Working weekdays, by time period. TfL’s ‘network of interest’.
2008/09 vs. 2014/15.
2008/09
average
delay (18
month
period)
2014/15
average
delay (18
month
period)
% change
1.5 1.7 17%
1.8 2.3 23%
1.6 2.1 31%
1.2 1.4 19%
1.0 1.2 12%
1.5 1.8 20%
0.7 0.8 19%
0.5 0.5 5%
0.8 1.0 23%
Source: TfL Surface Transport, Outcomes Delivery, based on data from Trafficmaster.
4.13 Journey time reliability for general road traffic
Introduction
TfL’s assessment of road network performance for MTS is primarily based on the
concept of journey time reliability, which is one manifestation of smoother traffic.
TfL’s journey time reliability metric considers the relationship of actual measured
journeys (using ANPR cameras) to a nominal average journey time that is
representative of motor vehicle journeys by road in London. This is measured
quarterly on a road corridor basis, covering most of the TLRN major road network in
London, and is aggregated to a London-wide index for the purpose of MTS
assessment (figure 4.7).
MTS trend
Against a current working target of 87 per cent of road journeys in London to be
achieved within five minutes of the nominal 30-minute average journey time,
recorded performance since the start of this measure in 2009 has mostly been
between 88 and 90 per cent. Seasonal factors are evident in the graph, for example
with JTR peaking at 90.3 per cent in the summers of 2009, 2011 and 2013. There is
little evidence of a clear trend in this indicator, although the recent tendency has
been very slowly downwards, indicating a marginal deterioration in reliability. Note
that, due to the widespread alterations made to the operation of the major road
92 Travel in London, Report 8