KC Streetcar Constructors Prepare for Winter Weather

It’s that time of the year again! We are officially in cold weather season. Within the construction industry, 40 degrees or lower is considered “cold weather.” Pouring concrete is one of the most susceptible types of work impacted by cold weather, but why is that? 

Concrete, and the pouring process, is especially sensitive to dropping temperatures because the typical chemical reactions that strengthen the concrete slow down and could lead to weaker concrete. When the average daily temperature drops below 40 degrees, concrete must be installed in accordance with ACI 306-16 Cold Weather Concreting. This is key to ensure the concrete is strong and durable.

KC Streetcar Constructors (KCSC) uses a variety of tools and techniques so crews can continue to work in frigid temperatures. To be able to continue pouring concrete in colder temperatures, ground heaters are used to warm the subgrade, or the surface that has been prepared for track installation. Additionally, laser thermometers are used to confirm that the subgrade is warm enough to pour concrete. 

Prepping for cold weather begins before the concrete arrives on site. The concrete plants use heated water to ensure that the concrete is between 50- and 70-degrees Fahrenheit when arriving onsite. At times, the plant may add an accelerator to the materials to allow the concrete to set quicker and generate more internal heat.

After pouring the concrete, crews quickly spread-out special blankets to keep the concrete warm while it cures. Sacrificial internal thermometers are used to verify that the concrete temperature is maintained during the curing process. External thermometers are also used to ensure the blankets and heaters retain enough heat. The concrete blankets are weighed down to protect the new concrete from the elements and to allow the heat to stay in place. The blankets are left for at least three days, depending on the amount of concrete poured, for example a sidewalk versus a track slab. Ground heaters are used to keep the temperature under the blankets at least 50-55 degrees Fahrenheit to allow the concrete to properly set. 

KCSC quality team members go the extra mile to ensure the team is prepared for cold weather conditions. A few weeks before the temperatures dipped below 40 degrees, the quality team delivered “cheat sheet” note cards to members of the KCSC team. These notecards represent each of the six types of concrete pours on the project: ductbank, track slab, station platforms, overhead catenary system foundations, roadway, and driveway/sidewalk/curb/gutter.  

Each cheat sheet notecard contains a table indicating what the concrete temperature needs to be based on the outside air temperature. The note cards also contain information for how long concrete needs to remain covered for each pour type and at which temperature needs to be maintained. 

In addition to the cold weather work plan, KCSC also prepares Main Street Extension work zones ahead of a snow or ice event. This includes salting metal plates and pedestrian bridges throughout the construction areas to prevent slick spots. 

KCSC crews operate in all-weather conditions unless it is unsafe to do so for our workers and the traveling public. All crew members are given insulated gloves and jackets ahead of the winter season and outdoor heaters are on site for the daily morning meetings. To keep KCSC crews safe, work may be postponed or suspended during extreme conditions or extreme temperatures.

As KCSC crews bundle up for a few cold months on Main Street and at the Singleton Yard Maintenance Facility, please continue to drive safely! Help keep work crews safe as they build this transformational project.

Stay warm and safe this winter, Kansas City!