Street Snow Removal


A short video of hard working staff plowing in formation during a recent snow storm. Note the additional "plow wing" on the lead truck that lets the operators plow a few more feet of roadway each pass. The wing can be raised and stowed out of the way with the push of a button. Three of the four trucks have a live bottom system, which spreads ice slicer before the rear wheels for better traction while a third truck in line has a vbox spreader at the rear of the truck.

Our Task

There are 303 lane miles of primary street routes (like Colorado Boulevard) in Thornton. There are 193 secondary route lane miles and an additional 741 lane miles of streets totaling 1,238 lane miles. Snowplows will continuously plow all Primary routes to keep roads open, followed by secondary routes as weather permits. Depending on the severity of the storm, the actual miles plowed and sanded are significantly more than the above average figure, since multiple plow passes are required on the roads.  

​​​​​​The city divides storms into three classes and responds accordingly. 

  • Class I - A storm that lasts less than 12 hours; snow accumulations of less than 4 inches.
  • Class IIA storm that lasts more than 12 hours; snow accumulations between 4 and 8 inches.
  • Class III A storm that lasts more than 24 hours, snow accumulations greater than 9 inches.

In the event of any snowstorm, the city's first commitment is to clear the primary routes, then secondary routes — and keep them cleared. In the case of a Class III storm (and only in this case) the city will also bring on contract equipment to clear all 741 lane miles of residential streets.

To see if your street is on a Primary or Secondary plow route, please see our snow route map located in the right hand corner of this page.

​​Streets - First Attention  

Priorities - The first priority for city plows are the primary routes: the major arterial streets such as Colorado Boulevard, Washington Street, 104th Avenue, 120th Avenue, and 136th Avenue. Next to be plowed are the secondary routes which include local collector streets, school zones, and fire station zones. ​Residential streets are only plowed for a Class III storm as defined above.

​During a StormIn a Class I or Class II storm, city crews will plow only selected streets identified as Primary and Secondary routes. Primary and Secondary routes make up 496 lane miles of Thornton's street system. In a Class I storm, Primary routes are treated within three hours of the snow beginning to accumulate on roadways. Secondary routes will be cleared of snow and ice after the primary routes are completed.

Tertiary Routes - In the event of a storm, which meets the Class II definition plus a prolonged period of freezing temperatures, a decision is made to plow Tertiary routes which include an additional 55 miles of neighborhood streets.  These routes are cleared by Street Operations personnel once the primary and secondary streets are cleared and treated.  These routes will receive one pass down the middle of the street, not a curb-to-curb street clearing.

During Class II and Class III storms, snowfall may be so heavy that only Primary routes can be maintained in a passable condition until the storm abates. When Primary routes are clear, then Secondary routes are plowed.  Residential streets are only plowed during Class III storms. 

Residential Streets and Plowing Shifts  

Residential Streets - After residential streets are plowed, residents will not necessarily see bare pavement. The emphasis for residential streets is to create a single passable lane down the middle that can be navigated by passenger vehicles equipped for winter travel. 

Blocked Driveways - During heavy snowfalls, problems arise for residents when mounds of snow left on the sides of streets may block driveways, these are also known as wind rows. Although a concerted effort is made to avoid this, it is not always possible. Residential streets are plowed down the center of the street in an effort to avoid covering sidewalks, parked cars, and blocking driveways. The city of Thornton does not remove or haul away snow as part of this program, and it is the resident's responsibility to clear these wind rows.

Snowplow Deployment and Shifts - When the snow hits, all of our crews and equipment work 12-hour shifts and in the event of a Class III storm, the city also has its contractors working to remove the snow.