INDIANAPOLIS — Hundreds of Hoosiers are dealing with insurance claims after slick roads led to hundreds of crashes around central Indiana on Monday, Dec. 2, 2024.
Between 3 p.m. that day and 6 a.m. on Tuesday, Dec. 3, Indiana State Police responded to 168 crashes in Indianapolis alone. According to IMPD, there were several hundred vehicle accidents and slide offs on surface streets. Police made reports on at least 148 of those accidents.
According to the National Weather Service, Indianapolis got 0.4 inches of snow on Dec. 2, with trace amounts sticking to the ground. That isn't much, but it was enough to create headaches for the evening commute and the morning commute the next day.
The question is why?
When it comes to snow, timing is key
Salt remains the most cost-effective way to treat roads for snow and ice. It works because salt lowers the freezing temperature of water, making it more difficult for ice to form.
As cars drive over snow, the friction from the tires melts the snow. If there is salt, the water mixes with it, and then takes much longer to refreeze. Wet pavement is slick on its own, but not nearly as bad as ice.
Given a little water, salt can melt ice on its own, but this is a lot slower than the melting that comes from tire friction. It also depends on air temperatures. Below about 15 degrees, even salt water freezes. Even when air temperatures are warm enough for salt to help, the thickness of the ice and the concentration of the salt have a lot of impact on how fast it will melt ice.
That means that putting salt on after the snow has fallen and after some of it has already melted and re-froze can be much less effective than pre-treating pavement before the snow starts.
Treatment started as the snow fell
By Friday, Nov. 29, the National Weather Service was forecasting possible flurries on Dec. 2. By Sunday, Dec. 1, the NWS was forecasting light snow in central Indiana.
Monday morning, INDOT conducted training for winter weather operations.
When 13News asked INDOT why road conditions were so poor, an INDOT representative said:
"Due to higher-than-forecast precipitation rates and accumulation amounts, INDOT was forced to react to roadway impacts during yesterday's snow event. As snow lingered, crews pivoted to utilizing rock salt in impacted areas mid-to-late afternoon and throughout the overnight hours.
While accumulations were light, generally under a half inch, traffic allowed the light snow to melt from friction and then refreeze from sub-freezing temperatures."
Indy DPW told 13News their crews were on the road about a half hour after the snow started:
"Snowfall began at about 2:30 PM yesterday and our crews were on the road around 3:00 PM treating the grounds for snow. Our teams remained active during and after the entire snow event and took special care to address bridges and overpasses, which are notorious for icing over and becoming slicker than street ways.
It is standard protocol to begin with a team of twelve drivers split evenly among each district and to deploy the rest of our drivers once their shifts begin. I can share that we had all of our drivers out on rotating shifts yesterday. The first shift ended at 11 PM, the next began at 11 PM and ended at 11 AM. This cycle continued through the snow event."
Drivers failed to adjust
The snow fell just before the evening commute and temperatures fell almost 10 degrees between when the snow started and when it ended. The friction from cars melted the snow, creating wet patches that quickly froze in the modest pre-rush hour traffic.
As traffic flow increased, drivers found slick patches underneath the light layer of snow. As accidents began to come in, it became harder for the road crews to treat the roads as they got caught in the backups.
Drivers also failed to adjust to the conditions.
"Most of the crashes we investigate involve someone going too fast for the road conditions. Remember, the crash report will never put the road at fault," Indiana State Police Sgt. John Perrine said.
He also said that some drivers over-estimate how effective their vehicle's safety features are.
"Don't get a false sense of safety because your car is equipped with all-wheel drive. Although that is a great safety feature and will help you, it doesn't give you the green light to drive faster or high speeds on these roads." Perrine said.