The Interstate 5 Bridge ranks as the nation’s 29th worst bottleneck on a top 100 list and the worst in Washington, according to American Transportation Research Institute findings issued Tuesday.
The 2019 Top Truck Bottleneck List assesses the level of truck-oriented congestion at 300 locations on the national highway system. The analysis, based on truck GPS data from nearly 1 million heavy-duty trucks, uses customized software and analysis methods, along with terabytes of data from trucking operations to produce a congestion-impact ranking for each location, the institute said in a news release.
The institute’s findings show that traveling on the I-5 Bridge between 9 p.m. and 5 a.m. traffic flows at 50 mph to 55 mph. Traveling outside that window, as any veteran I-5 Bridge driver knows, and you’re taking your chances. The slowest average speeds, the institute says, are at about 8 a.m. with an average speed between 30 mph and 35 mph and at 6 to 7 p.m. with an average speed of 35 mph. The overall average speed on the span is 41.2 mph.