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.

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405 Closure - Carmagedon in Southern California - 7/15 to 7/18, 2011

This Weekend an epic closure of the 405 freeway in Southern California plans to shut down. This article attempts to revel the details of the closure to help in planning your movement/travels this weekend! So lets go over the Five W's to get an idea about what is going on!

Who: The I-405 Freeway
What: 10 mile section closed for 53 hours
Where: The 405 Freeway, from the 101 to Highway 10
When: 10 pm on Friday July, 15 2011 - 5 am on Monday July 18 2011
Why: As part of a $1 Billion dollar reconstruction project, which includes the instillation of a HOV lane and a sound wall as well as upgrading on and off ramps to the freeway.


Some Pictures taken on Friday (7/15/2011) afternoon of the area are included here to show the equipment and future project areas. The first two is of Wilshire Blvd overpass over the 405 and the other picture is near Mulholland Drive.
 


A map of the 10 mile segment can be seen below.

Section closed for Carmagedon

It has been mentioned that, "if you think you think you're going to bypass the closure by some secret canyon route, you and a million other people have the same idea," said Andrew Neiman a L.A. police Lt. Some PR advocates of the closure have gone so far as to make T-shirts of the event, almost to a point of mockery.

While most articles are predicting [1, 2, 3] major delays, some say that the warnings may be so successful that traffic will be light as they were during the 1984 Summer Olympics. Well just have to wait and see how this all turns out, hopefully drivers plan accordingly and arrive at their destination safely.

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405 Northbound - Monday V.s Friday Traffic Comparison

Looking at the 405 Northbound Highway between Sand Canyon Ave and Jeffery Ave on Monday May 1st and Friday May 4th 2009, I found that this particular highway segment was interesting to look at, due to heavy traffic volumes in both the Am and Pm hours.
View Larger Map

Comparing the morning and evening times for Monday and Friday, we can draw some heavy conclusions about when people are leaving and getting on the road. The data has been collected from loop detectors on the highway, which I extracted using PEMS. I then looked at the Flow (vehicle/time) and speed(mph). The data is grouped into 5 minute intervals for the highest resolution avalable from PEMS. Before we look at the data plots, I would like to say that the more flow on the highway, resulting in more cars on the highway, which should reduce our speeds. Keep this in mind when looking at the graphs. The Flow was calculated as an average of all the lanes, thus giving one line in the graph, rather then four flow lines for four lanes. I left each of the lane speed data in there respective colors to give insight into the faster and slower lanes (More on this in another article).

Monday Flow and Lane Speeds

Key: Purple - Average Flow over all the lanes. Blue - Lane 1 (Inside lane next to divider). Red - Lane 2. Yellow - Lane 3. Green - Lane 4 ("trucking lane").

Friday Flow and Lane Speeds

Key: Purple - Average Flow over all the lanes. Blue - Lane 1 (Inside lane next to divider). Red - Lane 2. Yellow - Lane 3. Green - Lane 4 ("trucking lane").


Key: Blue - Monday. Red - Friday.

Here it seams the data is telling quite a compelling story. The flow on each of these days, rises quite rapidly in the morning time, but notice that the peek flow occurs 40 minutes apart on each of these days (6:45am on Monday and 7:25am on Friday). I believe this 40 minute time gap can best explained by the majority of cars on the road ways are people going to work. Mondays are a great day to kick off the week, and it seams most people try to start the week off right by trying to get to work early or on-time. Another interesting point of note, is the leaving times in the afternoon on both these days. On Monday we see people stay off the roads for a bit longer then on Fridays. Mondays peek Flow is seen at 5:10 pm. Friday however, we see a triple peek; Once at 2:45 (slackers), 3:40 (conservative effort workers) and again at 5:20 ('Over time' Workers). Overall the peeks occur earlier on Fridays then they do on Monday. The peeks are also more amplified on Friday, then they are on Monday.

Notice: the leave time in general is much more scattered, as people can usually leave there "work" at a more flexible time, then when they must arrive.

Assumptions: This is only for one highway, at one location on the highway, during one Monday and one Friday, However this is going to be true in all highways all across the world.

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