Snow and Ice Response

425 miles of city streets and 73 miles of multi-use paths are regularly plowed by the city and its partners when it snows. The goal of the program is to support multimodal travel and accessibility for all people by focusing on equity, safety, mobility and customer service before, during and after it snows.

When the city’s transportation system is impacted by snow and ice, our highest priority is to ensure safety and maintain emergency response capability. The interactive snow map shows which routes are cleared first by storm-size.

The storm size response framework divides streets maintained by the Transportation & Mobility Department into three priorities based on specific criteria. First priority street segments are high traffic streets and streets that serve critical highway and arterial emergency response routes and/or high ridership transit route stops. Second priority street segments are all remaining transit routes and critical emergency response routes, heavily-used alleys, and streets steeper than a 6.5% grade. Third priority street segments are streets with grades between 4% and 6.5%.

Plowing frequency depends on many factors including, street priority level, storm intensity and traffic volumes. Designated turn lanes on first priority streets will receive some ongoing service but will not be fully cleared until after snow stops. Generally, service frequency is as follows:

Priority 1 – traveled lanes will receive service every two to four hours throughout snowfall during all storm sizes.

Priority 2 – traveled lanes will receive service every three to five hours throughout snowfall during medium and large storms.

Priority 3 – traveled lanes will receive service every six to eight hours throughout snowfall during large storms.

Like other Front Range communities, the city does not typically plow residential streets.

There are several reasons the city does not typically plow residential streets and sidewalks after every storm, including:

• The resources and staff required to cover the scope to clear 100s of miles of side and residential streets is well beyond the current snow and ice response budget. Funding this level of response would take resources away from other essential city services.
• Many local roadways are narrow and large city trucks can only clear a single center lane, causing large amounts of snow to be piled against parked cars and creating snow walls across driveways. This can make it tough for people to access their vehicles or the road.
• Most residential streets are driven on prior to resources being available and plow trucks will only be able to clear loose snow and apply de-icer to intersections. Packed snow can remain on off-route streets even after trucks have plowed the street.
• In most cases, vehicle activity and the sun make residential roadways functional before city snowplows can get to them.
• Adding route mileage to clear snow from residential streets would also see more environmental impacts of increased snow and ice response – air quality, emissions, water quality and storm water infrastructure. Our level of response must be balanced with the city’s commitment to its climate goals .

Like most communities, city property owners, managers and tenants are required to keep sidewalks adjacent to their property clear of snow and ice within 24 hours after snow stops. See additional information in the section above.

It is the responsibility of the adjacent property owner, manager and tenant to clear a five-foot path on curb ramps within 24 hours after it stops snowing.

There are over 80 miles of multi-use path systems and 73 of them are cleared edge to edge once per day during and immediately after it snows by the city and its partners. For the remaining paths, it is the responsibility of the property owner, manager and tenant to clear the full width of the path, or a width of at least five feet on paths abutting their property within 24 hours after it stops snowing.

Bus stops are typically located within city right-of-way and are not considered part of the sidewalk nor subject to city code (BRC 8-2-13). Approximately 20% of over 550 bus stops in the city are cleared of snow through maintenance agreements between the city and RTD based on available resources. RTD and CU Boulder clear snow at 100 bus stops, city contractors at 40 locations and Shovel-A-Stop program volunteers at about 47 locations. View the section above for additional volunteer opportunities.

View the map of bus stops cleared by the city, RTD, CU and volunteers.

The city and its partners clear 73 miles of multi-use paths to prioritize multimodal transportation. Multiple passes of these areas are typically needed before they are completely clear of loose snow. Each pass takes approximately 12 hours.

Additionally, the city clears 179 miles of the on-street bike network. The interactive snow map shows which routes are cleared first by storm-size.

The storm size response framework divides streets maintained by the Transportation & Mobility Department into three priorities based on specific criteria. First priority street segments are high traffic streets and streets that serve critical highway and arterial emergency response routes and/or high ridership transit route stops. Second priority street segments are all remaining transit routes and critical emergency response routes, heavily-used alleys, and streets steeper than a 6.5% grade. Third priority street segments are streets with grades between 4% and 6.5%.

Shoveled areas, which include select curb ramps, median refuge islands and bus stops, are cleared by city contractors.

View the map of bus stops cleared by the city, RTD, CU and volunteers.

Four segments of the on-street bike network were added as an operational feasibility trial and are viewable on the interactive map. These gaps were highly requested for snow clearing during community engagement and will better connect the network of lower-stress on-street bike facilities that are accessible during the winter. Due to staffing limitations, these segments will be cleared at the end of snow response operations for medium and large storms. Identified segments for the operational feasibility trial include:

• Connection between 19th Street and 26th Street via Upland Avenue and Tamarack Avenue – provides low-stress connection that avoids construction on 19th Street
• 15th Street south of Iris Avenue – provides continuity to 13th Street Greenstreet and complements new enhanced crosswalk at 15th Street and Iris Avenue
• Juniper Avenue east of 26th Street – provides access to Elmer’s Twomile Path
• Old Tale Road and Gapter Road – provides continuity in the low-stress bike network east of Foothills Parkway and access to US 36 regional bikeway

Learn more and provide feedback on the pilot routes.

In heavy storms, snow can be pushed from streets and bike lanes onto sidewalks. This is understandably frustrating for adjacent property owners and people rolling, biking and walking but it is impossible to avoid with heavy snow accumulation. When there is no area between the sidewalk and the street, staff must choose between fully clearing a travel or bike lane and impacting an adjacent sidewalk. Typically, staff try to open vehicle and bicycle lanes as much as possible, while keeping sidewalks as clear as possible.

Sometimes snow may block driveways after city plows clear streets and paths. This can happen when storms produce large amounts of snow. This is especially true when the snow holds a lot of moisture, as it can create large balls of wet snow that move away from plows.

The city will continue the practice of plowing snow to the edge of the street to provide the clearest travel for bicycles and vehicles, which can sometimes leave a windrow or row of snow in front of driveways. There are tens of thousands of driveways on Boulder plow routes, making it nearly impossible for drivers to stop and clear each driveway entrance for two main reasons. First, safety is a concern, as plows have limited rear visibility, and clearing each driveway would require the driver to back up, putting children, animals and other vehicles at risk. Second, for the city to provide the most efficient and cost-effective snow response, continuous movement is required.

During winters when Boulder gets a large volume of snow, packed snow and ice will remain on off-route streets even after trucks have plowed the street. Plows and snow clearing equipment are designed to move snow from one place to another rather than remove it entirely. If Boulder experiences significant snow followed by several days of below freezing temps, the result can be layers of packed ice, and the city's equipment can’t break up packed ice.

Snow crews often must conduct multiple passes of areas before they are clear of loose snow. Even after multiple passes, normal travel conditions cannot always be maintained during winter storms and snow occasionally may be present, especially when temperatures remain below freezing for extended periods of time.

Plow drivers position the blade to clear snow from city streets during and after storms. The optimal weight of down pressure is set to manufacturer recommendations to avoid vehicle and roadway damage. The blade may appear to be above the street surface, but this is actually the plow riding on top of packed snow. Sometimes plows will keep their blade up to avoid removing anti-icing materials recently applied from another driver when traveling to and from their assigned routes.

City code (B.R.C. chapter 8-5) prohibits work in the public right of way without a permit, and the city does not issue permits for private parties to plow public streets. The one exception to this rule is the Knollwood subdivision because of how their annexation into the city was structured. The ordinance is intended to regulate work activities within the public right of way, and to protect the integrity and operation of the transportation system.

Yes. There is no city code provision that prohibits an HOA from plowing a private street.

When conditions allow, streets and multi-use paths are pre-treated to help reduce the buildup of snow and ice. Snow crews may also apply an anti-icer before a storm to minimize icy road conditions. If a storm starts as rain for multiple hours, pretreatment is ineffective because rain dilutes it and washes it off roadways.

While pre-treatments help reduce buildup of snow and ice, they do not prevent it entirely. Sometimes snow melts across the road and causes intermittent icy spots, snowfall rates are too intense for de-icing materials to be effective, or the effectiveness of de-icers has been reduced by snowfall before a plow truck can get back to that spot.

Depending on the weather, the city uses several types of anti-icers and de-icers:

• Salt Brine is a pre-treatment that helps reduce buildup of snow and ice
• Ice Slicer RS, a granular de-icer, is made up of complex chlorides that dissolve over time
• Meltdown Apex, a liquid de-icer, is a magnesium chloride solution, a plant nutrient and soil stabilizer that is less corrosive than other de-icing products

The city strives to sweep all primary and secondary streets and on-street bike lanes within three days of the end of a snowstorm to remove any surplus materials.

The city uses several types of anti-icers and de-icers, including Salt Brine, Apex Meltdown and Ice Slicer RS. All products are designed to minimize the impact of snow and ice on vehicles and work as freezing-point depressants. Using these products helps minimize impacts to air quality, as no sand or other traction materials are used, which can increase air particulate pollution.

The department’s 15 large plows all use modern diesel engines that meet state air quality requirements and are fueled by biodiesel.

The city has a total of 21 snow and ice control vehicles:

• 15 heavy vehicles for snow removal on major streets. This includes one “winged” snowplow to help move more snow away from streets in a single pass.
• Four small vehicles to clear bike lanes, collector roadways and priority residential streets
• Two small vehicles and a specialized piece of equipment dedicated to multi-use paths

Snow crews are split into two 12-hour shifts and perform snow and ice control around the clock until the storm event is over. Then, crews operate on a typical 8-hour schedule.

• On-road operators and fleet mechanics are on 12-hour shifts. Shift changes occur at noon and midnight.
• Off-road operators are on 12-hour shifts. Shift changes occur at 4 a.m. and 4 p.m.

Funding for the city’s Snow and Ice Program comes from the city’s Transportation and Mobility budget. Visit the city’s budget webpage to learn more.