Bellevue Studies Traffic Cameras To Improve Road Safety

BELLEVUE, WA — Bellevue city officials are sharing some lessons learned from a lengthy analysis of traffic camera videos that began last August.

Bellevue teamed up with Transoft Solutions to study 5,000 hours of footage from high-definition traffic cameras at 40 city intersections. Using additional software, the study measured traffic volumes, travel speeds, and "near-crash traffic conflict indicators," then used artificial intelligence algorithms to help identify emerging safety issues. The results were published in three reports this week.

The city recorded 172 crashes at 37 intersections during the study, broken down in this table:

In one report, the city also examined three hotspots identified during the study:

• 124th Ave. NE & NE 8th St.
  • Highest number of "interactions and critical conflicts."
  • Second-highest risk.
  • A change in left-signal phasing decreased conflicts by 60 percent.
• Bellevue Way NE & NE 8th St.
  • Highest pedestrian volume and second-highest number of "critical pedestrian conflicts."
  • A study of the videos found "clear pedestrian phase violations" and drivers choosing to cross the intersection in the "dilemma zone," between a light turning from yellow to red.
• 108th Ave. NE & NE 4th St.
  • Highest cyclist conflict rate.
  • Analysis showed most frequent conflicts were between cyclists and pedestrians in the crosswalk — due either to cyclists trying to beat the light or pedestrians crossing out of phase.

The city said its findings showed "near-crash events" captured on video were an accurate predictor of where future crashes might occur.

In a news release, the city summarized four other lessons gleaned from the reports:

• People riding bicycles are at greater risk than vehicle occupants: bike riders represented 0.1% of observed road users, pedestrians were 2.6% and drivers accounted for 97.3%. However, bicyclists were 10 times more likely to be involved in a conflict than drivers.
• Motorcyclists traveled at higher speeds and generated more critical conflicts than any other road user.
• More than 10% of drivers were speeding; half of them were traveling at more than 11 mph over the posted speed limit. Speeding incidence rates were relatively uniform on weekdays with a noticeable decrease around peak (commute) hours.
• 20,000 critical conflict interactions were observed among the 8.25 million road users recorded during one week.

According to the World Health Organization, incidents on the road rank among the leading causes of death across the globe, and the United States typically records more than 40,000 traffic-related deaths each year. In Bellevue, the Vision Zero initiative strives to eliminate deadly and serious-injury by 2030.

"Our City Council has long been committed to road safety and to Vision Zero," said Andrew Singelakis, Bellevue's transportation director. "To achieve this goal, we need a data-driven approach and our video analytics partnership gives us that."

Read an executive summary of the city's findings here.

Find all the reports on the Vision Zero project page.