Strikes are a commuting disaster, but what delays your daily Tube journey?

tube coming to station-2The Tube strike hitting London today will bring chaos to the city as millions who rely on the Underground to get to work resort to cars, bikes and unfamiliar bus routes to navigate their journeys.

Industrial action brings the system to a halt and has a catastrophic impact on the statistics TfL uses to measure the performance of the Tube. But away from strike days how is that performance measuring up, and what lies behind all those delayed trains and long waits in tunnels? Urbs decided to find out.

The good news is that the performance in terms of delays is getting better – 56% better looking at the average for 2003 to 06 compared to the last 3 years according to Urbs analysis – but as everyone seems to know anecdotally, some lines are better than others.

We looked at the statistics on delays for the past 10 years in what TfL calls the London Underground Performance Almanac. The key measurement is called Lost Customer Hours. This benchmark is calculated by multiplying the delays in minutes by the number of passengers. TfL records all delays over 2 minutes.

TfL uses the financial year from April to March and splits the year in 13 equal periods for performance measurement. Back in 2003/04 the average number of Lost Customer Hours (LCH) per period was 4 million. By last year it had come down to 1.7 million.

Put another way, in 2003/04 the Tube had a total of 52.2 million LCH, and in 2014/15 22.6 million. As it is quite hard to get your head around that number of hours, a year is 8,760 hours. An 80-year lifetime (current average London male life expectancy) is 700,800 hours. So delays have reduced from 74 London lifetimes to 32.

This may be good to know next time you feel you have waited a lifetime for a Tube, but what causes delays when it is not striking drivers?

Most lost hours are caused by problems with the train fleet, signals and what TfL calls customer actions. As our multi-coloured chart shows, the red, pink and black blocks representing these causes feature strongly every year.

Tube Causes LCH

The chart also shows the impact of one-off events such as strike action in 2010/11 and 2013/14, marked in orange, and the security clampdown following the 7/7 bomb attacks in 2005/06, marked in blue, which contributed 10.4 million LCH that year.

One-off events cause major disruption but their impact comes in precise peaks. The orange in the chart below shows how industrial action contributed to Lost Customer Hours last year, but the consistent problems were the red, pink and black blocks of fleet, signal and customer caused delays.

Tube LCH 2014-15

While overall performance has improved some lines are doing better than others. The Northern Line is most improved, though many of its regular users will tell you that it needed to be. The Central line has made the least progress in 10 years.

Tube delay improvement

In the past 12 months the Central Line has continued to struggle at times and delays have increased recently on the Jubilee Line.

Tubes lines delays 2014-15

The disruption of strike action is severe but mercifully short-lived. The longer term causes of delay are the key variables in any mass transit system – its trains, reliability of infrastructure and passengers. Next time you’re stuck take heart and remember, the trend is for fewer delays.

Source data

See also

Passenger data reveals busiest stations where Tube strike will hit hardest

Crime down nearly a third in 5 years on buses, Tube and trains

How TfL may be key to success for Apple Pay in the UK