MileCheckHow often are chains or traction tires required on Washington's passes?
Counted through Oct 29, 7 AM Pacific ยท from WSDOT's pass reports, saved every hour since Sep 26
So far this season, traction tires were advised on five Washington passes on October 28 and required on three passes on October 28 and 29.
These counts start September 26 and run through the time above. We update them as more restrictions are posted.
What did each pass show?
Each number is the count of hourly reports in which WSDOT's restriction line for that pass read closed, traction tires advised, or traction tires required. One hour is one report. All times are Pacific.
| Pass | Closed | Traction tires advised | Traction tires required | First posted |
|---|---|---|---|---|
| Snoqualmie Pass (I-90) | 0 | 6 h | 0 | Oct 28, 4 AM |
| Stevens Pass (US 2) | 0 | 10 h | 0 | Oct 28, 3 AM |
| White Pass (US 12) | 0 | 16 h | 1 h | Oct 28, 3 AM |
| Blewett Pass (US 97) | 0 | 6 h | 0 | Oct 28, 4 AM |
| Chinook Pass (SR 410) | 20 h | 0 | 4 h | Oct 25, 5 PM |
| Cayuse Pass (SR 123) | 17 h | 24 h | 0 | Oct 25, 8 PM |
| SR 410, Crystal Mountain to Greenwater | 21 h | 0 | 4 h | Oct 25, 4 PM |
| Mt. Baker Highway (SR 542) | 66 h | 0 | 0 | Oct 25, 4 PM |
The advised column counts hours at advised only. A pass that requires traction tires was advised first, and those hours are in the required column. WSDOT's "traction tires required" line on White Pass, Chinook Pass and SR 410 also said chains are required on vehicles over 10,000 pounds gross weight.
When did it happen?
- October 25 and 26. WSDOT listed Cayuse Pass, Chinook Pass, SR 410 from Crystal Mountain to Greenwater and the Mt. Baker Highway as closed, for between 17 and 24 hours each. The Mt. Baker Highway was listed as closed again from October 27 at noon, with 42 hourly reports so far.
- October 28. Traction tires advised from about 3 AM on Stevens Pass (10 hours) and White Pass (16 hours advised and one hour required), from 4 AM on Snoqualmie Pass and Blewett Pass (6 hours each), and from 6 AM on Cayuse Pass (24 hours).
- October 29. Traction tires required on SR 410 near Crystal Mountain from about midnight and on Chinook Pass from about 4 AM, 4 hours each in the reports so far.
What does this not tell you?
- These early-season counts do not show how often restrictions are posted over a full winter.
- WSDOT posts one restriction line for each pass. It does not separate eastbound from westbound in this report.
- We saved 724 of 783 possible hourly reports. The 59 hours we did not save are not counted, so some totals may be low.
- Loup Loup Pass SR 20, North Cascade Hwy SR 20 and Wauconda Pass SR 20 showed "no current information available" for most or all of the period, so they are not in the table.
- These are past restrictions. Check the current WSDOT pass report and the signs on the road before you drive.
What about Colorado and Montana?
Their feeds post notices rather than a line for each pass, so we count postings, not hours. Colorado posted its Traction Law (Code 15) 9 times on I-70, SH-9 and US-550, on Oct 14 and Oct 24. Montana posted "chains required for towing units" 14 times on I-15, I-90, MT-200, US-12 and US-287, on Oct 11, Oct 23, Oct 26 and Oct 28. California's chain control records in our log all carry one label and one start day, so we cannot tell separate events apart and leave them out.
Where do I check before I drive?
- WSDOT mountain pass reports, the source for this page.
- Do I need chains in Washington? What each level means and the fines, with sources.
- Washington road conditions right now, with closures and cameras.
- Snoqualmie Pass driving conditions and Stevens Pass.
- Which Washington roads close for winter?
How is this counted?
MileCheck saves WSDOT's mountain pass report every hour. For each pass we read the restriction line and count the hours at each level. The method and the script are in the MileCheck repository as scripts/chain-stats-wa.py. The page is refreshed at month end and after a big storm.