Curious as to where a snow plow is on this snowy Friday?

The city of Ann Arbor's online snow plow tracking system allows you to follow the salt trucks on their routes.

From the online portal

The online portal, called AVL Web Tracking, works optimally on the Internet Explorer browser as it was designed for corporate use, said Kirk Pennington, field operations supervisor.

To find where the snow plows have been, click the "Map Contents" tab on the left to expand the options, and then click on the "History Layers" field. The map will show the most recent eight hours of data.

Heavy snow began about 6 a.m. Friday. The city of Ann Arbor had its five night shift trucks spread salt on city roads from 4 a.m. to 6 a.m. Friday, Pennington said.

The city of Ann Arbor also staffs a call-in snow desk during snow events to respond to resident questions. It can be reached at (734) 794-6367.

Between 6 and 9:30 a.m. Friday, eight trucks were spreading salt and clearing snow from city roadways, Pennington said. After 9:30 a.m., a total of 10 plows were on city streets.

The city's salt crews give first priority to clearing freeway exit roads, including Plymouth Road, Barton Drive, Miller Road, Jackson Road and Washtenaw Avenue, Pennington said.

One truck is assigned to clearing downtown Ann Arbor, which concentrates its efforts on Division, Main, State, William and Liberty, Pennington said.

"Everything is based on traffic volume," Pennington said.

Because of the intensity of the snowfall Friday morning -- a rate of about three-fourths of an inch per hour -- the salt that was spread on Ann Arbor roads was not immediately effective, Pennington said.

Each salt truck driver has a route that's 2.5 hours long -- meaning he won't cross the same section of pavement twice for 2.5 hours. The drivers are instructed to maintain at least one through lane of traffic on the streets. Pennington said that doesn't necessarily mean the drivers will hit bare pavement.

The city can change the timing of traffic signals at 18 intersections for snow and ice events, Pennington said.

Four of those intersections are on Glen Avenue near the University of Michigan medical campus at Ann Street, Catherine Street, Fuller Street and East Huron Street.

Buses have a tendency to get stuck in snowy conditions on the Glen Avenue hill leading towards East Huron Street when they stop at traffic lights on the hill, Pennington said.

Police have the option of enacting a special traffic signal timing at that light to allow for better traffic flow up the hill -- but they didn't trigger the special signal Friday, Pennington said.

"Any time snow is causing delays on the hills they request that the timing be changed," Pennington said.

City of Ann Arbor crews salted that section of Glen Avenue twice Friday at 7:24 a.m. and 8:20 a.m., Pennington said.

Amy Biolchini covers Washtenaw County, health and environmental issues for AnnArbor.com. Reach her at (734) 623-2552, amybiolchini@annarbor.com or on Twitter.