Thousands of getaway travelers will spill onto Washington area highways this week, heading out of town for the long Memorial Day weekend. Those in the know will think twice before hitting the road Thursday afternoon.

 

Traffic analysts at the TPB recently examined historical traffic information on area freeways in the days leading up to Memorial Day weekend. The biggest takeaway was that traffic is consistently worse on Thursday than on Friday, running counter to a common perception that the Friday before the holiday weekend is the worst time to travel. This confirms the findings of a similar analysis last year which first showed the trend.

 

 

In each of the last five years, Thursday afternoon saw worse traffic overall than Friday. The average Travel Time Index, a measure of travel delay, ranged from 1.5 to 2.0 in each of the years studied. That means that on average it took 50% to 100% longer to reach one’s destination than on a day with no traffic. On some routes at certain times of day, the TTI soared to more than 4.0. (See hourly TTI tables at end of article.)

 

 

The TPB’s researchers say this Thursday-before-the-holiday phenomenon is caused by two overlapping travel trends. One is that Thursday afternoons are already the most congested time during a typical, non-holiday week thanks to regular rush-hour commute traffic. The other is holiday travelers looking to get an early start to the weekend by leaving on Thursday. Together, the two trends add up to unusually bad traffic.

 

The researchers found two other noteworthy trends in their analysis.

 

One is extreme year-to-year variability in the magnitude of traffic back-ups on Thursday afternoon, which makes it hard to predict how bad traffic will actually be. In 2014, for example, the Thursday before Memorial Day turned out to be the worst traffic day of the entire year. In 2015, Thursday was still bad, but at its worst point was still only about half as bad as 2014.

 

 

The researchers aren’t exactly sure why this variability is occurring, but say that disruptions caused by traffic crashes, road construction, or unusual weather are amplified with so many more people on area roadways.

 

The other trend is that, in some years, Wednesday is even worse than Thursday, making the mid-week day an equally bad choice for hitting the road for the holiday weekend.

 

Friday isn’t exactly a breeze, though

 

Although Thursday is usually worse than Friday, travelers can still expect significant back-ups on the last day before the holiday weekend. According to the analysis, the average regional TTI still routinely tops 1.5 on Friday afternoon.

 

Another key Friday trend is that back-ups get started earlier in the day. The analysis showed that traffic usually begins to ramp up around 11:00 A.M., with the worst conditions setting in mid-afternoon and lasting until about 6:00 P.M.

 

The best times to travel are late Thursday and early Friday

 

So when should travelers try to get away? The latest analysis shows that late Thursday night and early Friday morning are the least congested times on area freeways. Pretty consistently for the last five years the Thursday afternoon rush has ended around 8:00 P.M., with traffic not picking up again until around 11:00 A.M. on Friday. That leaves a 15-hour window when traffic is virtually non-existent, though much of that time is overnight—not exactly the most desirable time to travel.

But remember: every route and every year is different

 

Regional averages don’t tell the whole story. Some routes see heavier traffic than others. Crashes, construction, and other disruptions can lead to unusual or unexpected delays. Weather also plays a role. Day-of weather conditions can affect traffic in real-time while weekend forecasts can impact how many people head for outdoor destinations like the beach or mountains.

 

To help break things down, the TPB’s researchers compiled a set of animated maps and detailed tables showing hourly traffic conditions on the region’s seven major “getaway” routes over the last few years. The maps and tables help paint a more complete picture of traffic patterns and how they vary year to year. Individual travelers may be able to use these tools to get a better sense of the best times to plan their escape.