Traffic Payout

Travel numbers from Thanksgiving 2008 show more drivers may have made a weekend out of it. Compared to 2007, travel decreased slightly on the Friday after Thanksgiving, while increased – in some cases close to 40 percent – on the Sunday of Thanksgiving weekend.

Prior to the holiday weekend, WSDOT posted information on typical cross-state holiday travel on its Web site and its travel predictions were very close to actual traffic counts for Wednesday through Saturday.

Sunday was a different story. Here’s what we found:

• Compared to 2007, many drivers stayed in Eastern Washington over the weekend.
• On I-90 over Snoqualmie Pass, close to 180,000 made the trip Wednesday through Sunday, an increase from 2007 of just 2,150 vehicles (1.2 percent).
• Westbound travel was down 12,900 (12 percent) on Friday, but up 25,200 (13 percent) Sunday.

Snoqualmie is typically very busy for Thanksgiving. Another busy Turkey Day spot is Washington’s only section of I-5 with just two lanes in each direction - the area just south of Olympia through Lewis County. We have projects going on to widen it.

Here’s the 2008 numbers for I-5 south of Olympia:

• For the entire weekend, close to 350,000 vehicles traveled here (Wednesday through Sunday), an increase of just four percent from 2007.
• But looking at the numbers from Sunday alone indicate there were 68,600 cars on the road here, 16,000 (30 percent) more than in 2007.
• Sunday's southbound travel was up 19 percent and northbound travel up 41 percent.

Okay, so here’s the big question…why? Forty one percent is a big number – why and what were you all doing Sunday? One thing we do know it wasn’t the weather. It was pretty good all over. Fog and frost slowed Snoqualmie Pass traffic in the early morning hours, however the weather did not cause serious problems or long delays for holiday travelers.

By the way, for those who like numbers, it looks like we were right on in Tacoma. On the SR 16 Tacoma Narrows Bridge toll plaza, we correctly predicted between 60 and 75 percent of drivers would use the manual toll lanes during peak travel times (6-11 p.m.) on Thanksgiving Day. It seems five-mile backups were reported at times, with wait times up to 40 minutes. To help these drivers, the Washington State Patrol temporarily opened the HOV lane to all electronic toll payers with Good To Go! accounts. Besides the Thursday rush, there were no backups reported for the remainder of the weekend.

Question of the day:
Why are there two temperatures listed for Stevens Pass? Where are they taken at? I can see 1-2 degree difference in them but sometimes there is 5 or more degrees difference.

Answer:
There are three temperatures displayed on all of the mountain pass pages. The temp in the yellow "Pass Report" box next to the picture of whatever pass you're looking at is what is radioed in to our various Traffic Management Centers from the thermometer on the maintenance supervisor's pickup. That's the air temperature in the shade on the roadside wherever he or she is when they call in the pass report and set the traction restrictions, if any. As a result, the location could vary a mile or more from the summit, depending on the pavement conditions the supervisor has encountered as he/she makes the assessment. That's a call that takes place every 4 hours from November through March. It means that at 1 p.m., you're looking at a temperature that is an hour old. Below the camera image is a blue box labeled "Current Weather". A road weather information station provides that data every few minutes to the web page. The thermometers measure the air temperature and the pavement temperature at the summit of the passes. These are also subject to the influences of any permanent location - sunshine - a bird perching on a sensor or even a vehicle stopped on top of the pavement sensor.

Yesterday, for example, Stevens showed a temperature of 37 for the noon pass report, but by 1 p.m., the current weather box showed an air temperature of 48 and a pavement (surface) temperature of 53. A half hour later, when the sun went back behind the clouds, the temps had dropped to 47 and 51, respectively.

The Blewett pass page showed a similar pattern - 42 degrees in the pass report box and in the current weather box, 52 - air, 42 - surface at 1 p.m.

I checked Snoqualmie, Satus, etc. and Loup Loup (37-37-37) was the only one that showed all three matching, and then only for about fifteen minutes.

You might think we ought to eliminate the temp in the pass report box to eliminate confusion - and we would except that the info in the yellow box is what also appears on several other of our web pages, the 5-1-1 phone system and Highway Advisory Radio's, and NOAA's web site which is what Associated Press uses to provide its member's "news". All of those systems are automated and when conditions do change rapidly, forcing us to change the traction restrictions sooner than the standard "every four hour" schedule, then all of those change, too. It really wouldn't make much sense to update the mountain pass reports every 3 to 10 minutes because the temperature changed a degree or two - and if someone is looking at the pass pages, between the picture, the pass report and the current information, they ought to be able to decide if they want to go or not.