The morning commute on State Route 520 has become increasingly congested but the exact cause remains somewhat of a mystery.
Drivers have been reaching out to KIRO Radio in the last few months to ask why the westbound approach from I-405 has become so crowded during the morning commute.
KIRO Radio traffic reporter Chris Sullivan began noticing heavier traffic on the map between I-405 and Medina in late Fall. That congestion occurs between 7:15-8:30 a.m.
Travis Phelps with the Washington State Department of Transportation says traffic volumes there have been steadily increasing.
“Between 2012 and the present day, traffic volumes on westbound 520 during the morning commutes has actually jumped up by about twenty-four percent,” Phelps said.
That is kind of odd, considering that tolling began on State Route 520 in December of 2011, and drivers have been avoiding the bridge over Lake Washington to skip the toll. But what’s interesting about this increase in volume is that the bridge has seen its biggest jump in the last 12 months.
“Five percent of that increase has happened just within the last year,” Phelps explained. “That five percent was the straw that really broke the camel’s back and that’s where we’re starting to see those really big slowdowns starting to last a little bit longer.”
Phelps doesn’t have a reason for why drivers are returning to the toll bridge, but they are.
“Oddly enough though we haven’t seen a very big spike in traffic volumes across the I-90 floating bridge,” he said.
State Route 520 does usually have the faster travel time, despite the toll.
Maybe drivers are warming up to tolling.
The new 520 bridge opens to the public next month. That might smooth the drive through Medina, but it will likely cause more backups mid-span going westbound where the bridge will transition from three lanes to two approaching Montlake.
“There may be a little bit of a shakeout period once the new bridge does open, but [drivers] will pick up on the changes in traffic patterns,” Phelps said.
Despite the increase during the morning commute over the last five years, overall volume on the bridge is still down 20 percent from pre-toll levels.