The impact of public transportation strikes on use of a bicycle share program in London: interrupted time series design.

OBJECTIVE: To investigate the immediate and sustained effects of two London Underground strikes on use of a public bicycle share program. METHODS: An interrupted time series design was used to examine the impact of two 24 hour strikes on the total number of trips per day and mean trip duration per day on the London public bicycle share program. The strikes occurred on September 6th and October 4th 2010 and limited service on the London Underground. RESULTS: The mean total number of trips per day over the whole study period was 14,699 (SD=5390) while the mean trip duration was 18.5 minutes (SD=3.7). Significant increases in daily trip count were observed following strike 1 (3864: 95% CI 125 to 7604) and strike 2 (11,293: 95% CI 5169 to 17,416). CONCLUSIONS: Events that greatly constrain the primary motorised mode of transportation for a population may have unintended short-term effects on travel behaviour. These findings suggest that limiting transportation options may have the potential to increase population levels of physical activity by promoting the use of cycling.