A typical winter brings 46 inches of snow to the Hartford, Conn., area. Skiers, snowboarders, and other winter-weather enthusiasts love it, but not during the workweek if they must negotiate slippery sidewalks and parking lots to get to their jobs.
“We are always concerned about our employees slipping and falling in our parking lots and walkways during the winter months,” says David Billard, facilities engineer for Pratt & Whitney. Internationally known for innovation in aircraft engine manufacturing, Pratt & Whitney opted for an innovative approach to this safety challenge as well.
Management installed a new technology called SafeLane Surface Overlay. The system is designed to keep ice away and people safer in the parking lot and pedestrian walkways leading up to their engineering building.
“We have high expectations that this will prevent employee injuries resulting from the winter weather,” says Billard. “If the technology performs as well as expected, we plan to add the overlay to more of the walkways and parking lots on our East Hartford campus.”
SafeLane overlay is made up of a patented combination of epoxy and aggregate rock. The material acts like a rigid sponge, storing anti-icing chemicals inside, and then automatically releasing them as ice and snow develop. The overlay helps prevent frost or ice from ever forming, resulting in a safer surface.
Developed at Michigan Tech University, the technology was licensed to Cargill in 2003 and has met with an enthusiastic response. SafeLane overlay was first made available to state departments of transportation for bridges, overpasses, dangerous intersections or stretches of roads, entrance and exit ramps, and approaches to toll barriers.
By the winter of 2005-06, the overlay had been installed on seven bridges and two ramps (on grade), both concrete and asphalt surfaces, for a total of nine test sites in six states.
The nine sites had a combined average of 35 winter weather-related accidents per year before the overlay and none after its installation, according to an analysis commissioned by Cargill, by leading ice and snow control expert Wilfred Nixon, president of Asset Insight Technologies and professor of engineering at the University of Iowa.
The results led to requests for commercial and airport applications of the technology and the introduction last year of SafeLane CA-48 Overlay. This system has all the same anti-icing and anti-skid benefits of its original, but usues a smaller aggregate well-suited for sidewalks, pedestrian walkways, parking lots and ramps, airport baggage handling areas, and other outdoor commercial areas. By the end of 2006, SafeLane overlay had been installed at 30 sites in 17 states.
In October 2006, SafeLane CA-48 overlay was installed for the first time in a 2360-square-foot parking lot and its walkways in South Portland, Maine. A month later, Pratt & Whitney established its own test site on the 1900-square-foot pedestrian walkway at its headquarters in East Hartford.
“We've been following the technology for about a year and a half as it was applied to roads and bridges,” says Billard. “When the pedestrian version became available, we were anxious to get it installed so that we could test it this winter,” he adds.
Laying down the system is a simple process that follows American Association of State Highway and Transportation Officials Task force 34 protocols. Step one involves removing oil and contaminants, including surface repair if needed. Next, concrete surfaces are shot-blasted to an International Concrete Repair Institute level of 5-7. This roughens the surface and ensures a good chemical bond.
Although SafeLane overlay represents revolutionary new technology, it is applied in a decidedly low-tech manner. Crews use squeegees to manually spread the sticky, black epoxy across the parking lots and walkways.
The installer broadcasts the aggregate immediately across the surface using a shovel. The goal is to keep enough rock exposed to the surface so it will soak up and react with the anti-icing chemical. The aggregate acts as a reservoir to keep the chemical in place, while the chemical prevents ice crystals from forming and bonding to the surface.
Then, the epoxy sets up for seven to eight hours, depending on the temperature. After it cures, loose rock is scraped off and vacuumed by a sweeper truck, followed by leaf blowers. The overlay requires only one application of epoxy and aggregate, unlike road and bridge installations in which a second coat is applied following the same protocols. The result is a lower-cost installation that still provides all the same anti-icing and mobility benefits.
Prior to winter storms, the overlay is “charged” with liquid anti-icing chemicals. The overlay absorbs and holds the chemicals in place, automatically releasing them when the conditions are right for the formation of ice or snow. It continues releasing them over multiple winter weather events.
Oddly enough, New England didn't get much such ice and snow this winter. So as the end of winter neared, it was difficult to come to any conclusions as the results at each test site.
But that could well change with the next forecast. And, just as SafeLane overlay is already reducing accidents and making roads and bridges safer for motorists, it will be in place at these businesses, ready to help reduce slips, falls, and injuries for pedestrians.