At last count, the metro area had 110 authorized park-and-ride locations where commuters can leave vehicles for the day and hop on transit (or carpool) to get to work, sporting events or anywhere else they need to go.

Lots of people use them. According to the Met Council's 2015 Regional Park-and-Ride System Report, there were 19,340 vehicles in the lots when the annual survey was taken in late September and early October 2015. That represented a 5.9 percent increase from the 18,265 users counted in 2014 and the highest in the past five years. At the same time, it wasn't significantly higher than the low-water mark of 18,104 set back in 2012, meaning usage has remained fairly flat between 2011 and 2015.

For the record, the regional park-and-ride system has 33,907 spaces and about 57 percent of them are used on an average day. That's down from the high of 79 percent in 2006 when there were far fewer parking spots available. The annual survey tracks facility use to identify emerging travel patterns by park-and-ride users across the Twin Cities region. It also is used by planners to determine where to put new facilities and update service.

And that's where another study conducted by University of Minnesota Department of Civil, Environmental and Geo-Engineering Prof. Alireza Khani could come in useful. While much has been written as to why commuters use park-and-rides, Khani wanted to know what factors influence where they decide to park. Knowing those answers may come in handy when future decisions are made on which park and rides to keep, where to build new ones and where to expand transit service and amenities to maximize ridership.

A natural assumption is that commuters use the lot or ramp closest to their home or one that will minimize the time spent on a bus or train. But "choosing a park-and-ride location is really complex," Khani said.

From his research, Khani identified five key findings. Generally park and ride users' decisions come down to the time it takes to get to the park and ride, the frequency and types of service (regular route, express or limited stops) available, how much time the transit portion of the trip will take, and whether it will require a transfer. They strongly dislike transfers.

Demographics also factor in, Khani found. For instance, passengers who were over 35 didn't mind transit trips that took longer while younger riders were motivated by shorter trips. Transit riders with higher incomes were not as concerned with how frequently buses or trains ran, while lower-income passengers were. Nonwhite transit users preferred to use a freeway to access a park and ride while whites preferred using city and local streets. Amenities such as ample parking spots, lights and security features that made riders feel safe also play into the equation.

"For different characteristics, we have different behaviors," Khani said. "Many factors go into their decision. That makes it harder for planners."

About Hwy. 169

Cold and snowy weather has prompted MnDOT to push back the closure of the Nine Mile Creek bridge on Hwy. 169 from Tuesday until Jan. 17. Readers have asked if ramps to Bren Road and Lincoln Drive will remain when the bridge closes. Yes, they will. Drivers will be able to use Hwy. 169 between Crosstown and Bren Road and I-394 and Lincoln Drive, too.

Follow news about traffic and commuting at The Drive on Got traffic or transportation questions, or story ideas? E-mail, tweet @stribdrive or call Tim Harlow at 612-673-7768.