Monday, September 26, 2011

Bay Area Traffic

Commuting for work in bay area is tough during peak office hours, freeways like 101, 880 can test anybody's patience. I commute to work everyday driving for about 25 miles each way, drive times can range anywhere from 30 minutes to 1 hour depending on the time of day.

I know by personal experience that it did feel a little easy driving in 2008 and 2009 during the peak of subprime mortgage crisis. This would suggest unemployment rate inversely affects the traffic congestion, higher unemployment and less people have a workplace to commute to.

To validate this lets look at the traffic congestion trend for the last 20 years (1990-2009) and the unemployment trend during the same period.

Using the traffic congestion data available at the Urban Mobility Information at Texas Transportation Institute, I plotted two measures - Travel Time Index and Annual Delay per Auto Commuter. Travel Time Index is the ratio of travel time in the peak period to travel time in free-flow. A value of 1.30 indicates a 20-minute free-flow trip takes 26 minutes in the peak. Annual Delay per Auto Commuter is the yearly sum of all the per-trip delays for those persons who travel in the peak period (6 to 10 a.m. and 3 to 7 p.m.). See charts below:

Below is a chart that shows the unemployment rate in the counties of Santa Clara and San Francisco using the data available at California Employee Development Department:

The traffic congestion trend almost inversely followed the unemployment trend. This raises curiosity as to what economic events caused these sharp surges and drops. Saving and loan crisis and the housing bust led to recession of 1990-1991. Coupled with high gas prices due to gulf war the unemployment rose sharply. From 1995 to 2000 we see a drop in unemployment during the dot com bubble. March 2000 marked the dot com bubble burst with a sharp decline in the stock market and high unemployment particularly in technology sector thus impacting bay area. By 2004 economy started to turn around until we saw the subprime mortgage crisis of 2008.

No comments:

Post a Comment