Thanksgiving I-5 and I-405 Traffic Congestion Analysis: When to Drive North

Holiday travel is always a bit more.....congested. While the season brings friends and family closer, this comes at a cost of travel. Some have short distances to cover, while others much further distances. Regardless travel is typically required. For those travelling in the Southern California region, the following graphs maybe beneficial in determining when to make their journey.

The following graphs show a wealth of information to help analyse when an appropriate departure time maybe. The following contour plots show different color's to represent varying speeds. The X-axis shows time of day, while the Y-axis shows a distance (in this case a post-mile on the highway). These graphs are tailored specifically for travel originating in Irvine and travelling north. The focus is mainly on the Los Angeles region which is so well known for it's snarling traffic. Here is an example of the I-405 northbound freeway for Thanksgiving eve from 2009.

I-405 Speed Contour (2009) Source: AAA

From this plot we can see that speeds are below 30 mph until about 18:00 near the 12 postmile. Also we can see additional bottlenecks further down the roadway around the 55 postmile. A trajectory departing from postmile 0 would be optimal to leave after 18:00 to avoid traffic congestion.

We can also produce these contour plots for the I-5 northbound freeway for the past 5 years to see if there is a general travel pattern for thanksgiving travel. These plots have distance on the Y-axis from the El Toro Y in south Irvine to the End of the Los Angeles County line in the north. Speed is indicated on the right hand side of the image with yellow and white meaning 60 mph or more.

I-5 Speed Contour (2007) Source: AAA

I-5 Speed Contour (2008) Source: AAA

I-5 Speed Contour (2009) Source: AAA

I-5 Speed Contour (2010) Source: AAA

I-5 Speed Contour (2011)   Source: AAA

Based on these spatio-temporal plots, we can say that it is better to leave Irvine after 7:00 pm  to keep speeds above 50 mph for most of the travel north on I-5. There still seams to show congestion while leaving LA county line, but it will be minimal considering what those ahead of you went through. The typical pattern from these 5 plots show a significant decrease in congestion compared with the massive slow down in 2009 to the 2010 and 2011 speed contour plots. The congestion appears to form as early as 10:00 am.

Happy Thanksgiving, and drive safely.

Speed Contour Plot Credit: AAA - Ankoor's Amazing Analysis.