Vehicles per minute on State Route 20 for a mid-day portion of Labor Day 2020.
By Gerald Smith
Perceptions of visitor numbers to the Methow Valley over the recent holiday weekend could easily generate both positive and negative reactions by the end of Labor Day.
The coronavirus restrictions that impacted tourism during the early weeks of the pandemic are officially still in effect, but one might doubt the compliance based on cursory observation. To help evaluate the magnitude of the human stream coursing through the valley at the end of the long weekend, a vehicle number count was conducted for comparison with previous data recorded by the Methow Valley News.
• Methods of data collection: A vehicle count was carried out between 10 a.m. and 4:15 p.m. on Labor Day, Sept. 7, from a Mazama location along State Route 20 near milepost 179. During each hour, manual counting of vehicle numbers and direction was recorded for a 15-minute period beginning at the hour (10-10:15 a.m., for example). These 15-minute periods were taken as representative of each hour. Vehicle flow rate was calculated as the number per minute. In addition, during the first period a video of the roadway was recorded and later used to determine the variability of the count minute-to-minute.
Results and discussion
Labor Day was sunny with dry road conditions and moderate wind in the Mazama area. Relatively heavy traffic numbers were observed throughout the day with about 77% being westbound. The 11 a.m. hour had the greatest vehicle numbers with 166 total during the 15-minute period.
Assuming the full hour had a similar flow rate to the first 15 minutes, approximately 664 vehicles passed during that hour. On average there were 11.1 vehicles per minute, which is less than 6 seconds between vehicles. For comparison, traffic data reported for Labor Day in the Methow Valley News previously has always been lower. For example, 325 vehicles per hour in 2019, 502 in 2017 and only 212 in 2015 (with the latter two measurements made by Bob Spiwak from near milepost 185).
The accompanying chart shows the average traffic flow rate across the recording hours. By late afternoon, the count had dropped to about 57% of the peak value at 11 a.m. Within any measurement period, there were waves of closely spaced vehicles and then quiet periods with widely spaced vehicles. For example in the 10 a.m. hour, as many as 19 or as few as 5 vehicles passed within a minute.
Combining the seven periods of 15 minutes each, a total of 904 vehicles were counted. When counting across full hours, this translates to about 3,600 vehicles passing through the Mazama site. Using the Federal Highway Administration estimate of vehicle occupancy (1.7 occupants/car), one can estimate the number of people traveling through the Methow valley on Labor Day (1.7 occupants per vehicle times 3,600 vehicles). This estimate of 6,120 vehicle occupants is similar to the permanent valley population of about 6,000 people.
Of course, there was uncounted traffic both before and after the 10 a.m. to 4 p.m. data reported here. It is likely that visitor numbers more than doubled the Methow Valley population during the Labor Day holiday.
With Okanogan County in Phase II of coronavirus reopening as determined by the state and county public health officials, it is clear from this estimation of holiday traffic that the general public on both the west and east sides of the Cascades is now ignoring public health guidance which requests that only essential travel be undertaken.
