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4. Performance of the transport networks
network instability, increases at a greater rate, and journey times are therefore more
variable, the closer that traffic demand is to the carrying capacity of the network.
Figure 4.6
3.0
Average vehicle delay (minutes per kilometre) by functional sector of
London. Working weekdays, by time period. TfL’s ‘network of interest’.
Average delay (minutes per kilometre)
2.5
2.0
1.5
1.0
0.5
0.0
Central AM peak Central inter-peak Central PM peak
Inner AM peak Inner inter-peak Inner PM peak
Outer AM peak Outer inter-peak Outer PM peak
Source: TfL Surface Transport, Outcomes Delivery.
Average delay has shown a similar pattern to average speeds, with the time series
remaining relatively stable to late 2013, after which there has been a sharp increase
in all parts of London. Table 4.10 summarises the comparisons in terms of annual
averages, and Table 4.11 shows a comparison of 2008-09 and 2014-15 (based on
18 month periods in each case).
Figure 4.6 shows that, similar to trends in average speeds, the greatest increases in
average vehicle delay between 2014 and the first half of 2015 are all in the central
area. In the interpeak period, average vehicle delay increased by 18 per cent and by
10 per cent in the AM and PM peak respectively. Delay increased by 9 per cent in
the AM peak for both inner and outer London, however there was a slight decline in
delay in the PM peak for inner and outer London, at 1 per cent and 3 per cent
respectively.
Looking at the comparison between 2008/09 and 2014/15 (table 4.11), there have
been large increases in average traffic delay, particularly in the PM peak. The
greatest increase in the PM peak is in the central area, where average traffic delay
has increased by more than 30 per cent. The increase in traffic delay during the
interpeak in outer London is much lower than all other sectors and time periods in
London, increasing by only 5 per cent between 2008/09 and 2014/15.
90 Travel in London, Report 8