I-5 leading into downtown Seattle. ( Photo: Shutterstock )

You don’t have to be a rocket scientist to know that downtown Seattle traffic can be a nightmare. But it takes a mix of data science and transport engineering to figure out exactly what kind of vehicles are clogging the streets.

In a novel study, the Seattle Department of Transportation and the UW’s Urban Freight Lab are counting and analyzing truck traffic into the central city. The objective, said SDOT senior civil engineer Christopher Eaves, “is to get an idea of what our commercial health is downtown.”

Video from SDOT’s “Truck/Passenger Vehicle Cordon Count” project captured all traffic entering and leaving the downtown area on about 15 major and minor truck routes. The footage was taken in October at 48-hour and seven-day intervals and handed over to the lab earlier this week.

The Lab will count the vehicles and provide a detailed analysis of vehicle types, such as delivery trucks, construction vehicles, service vans and more.

“We know traffic is heavy; we know it’s busy,” Eaves said. “But this is the first time we know of anywhere where we’re evaluating those trucks’ use, so we can understand what is coming in and take the first steps to correlate why.”

The analysis gets into the nitty gritty. Barbara Ivanov, director of the Urban Freight Lab, said a student group has designed a typology to determine what kind of commerce is associated with the trucks – e.g., flower delivery, cupcake vans. The 48-hour and weekly viewing intervals allow the city to differentiate commercial traffic loads by day and time.

Eaves said the city is coming into a period of “maximum constraint,” with multiple megaprojects coming on board in next few years. These include the new Alaskan Way Tunnel, which will be tolled and may divert some traffic to the streets; expansion of the Trade Center above I-5; and the closure of the transit tunnel to all buses.

“These projects are going to change how people and goods come in,” Eaves said. The study will give the city baseline information about commercial movement in the city, and guide an update of the city’s freight master plan. The Lab will issue its complete findings in a report to be released Spring 2019.