Weather Why: Weather-Related Accidents on I-35

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There appears to be a high number of accidents that occur along I-35 between Des Moines and Ames. Channel 13 Viewer Kody wanted to know if that number of accidents was related to weather along that stretch of interstate.

Meteorologist Megan Salois had a feeling that the west-northwest crosswinds along a north-south interstate could potentially lead to a higher rate of accidents in the winter months. She contacted Andrea Henry of the Iowa DOT to confirm this suspicion. Henry did say that the frequent winds from the north-northwest lead to cars to blow across lanes of traffic on already slick roads when there is snow and ice on the interstate. Winter weather related accidents happen with more frequency on north-south roads, as opposed to east-west roads.

Henry also states that the winter usually has a higher number of accidents in general compared to the warmer months. On the positive side, winter crashes tend to be less serious with fewer fatalities. Vehicles tend to be driving slower and there is more snow in the ditches that can help cushion the crash.

interstate crashes

Henry had a few other reasons for the higher number of accidents along I-35 between Ames and Des Moines. You can read them here:

  • This section of interstate has more interchanges than a typical interstate.  Interchanges are where drivers enter and exit the roadway.  This is where drivers must slow down, speed up, or change lanes in order for motorists to enter and exit the interstate safety.  Crashes occur more often when drivers have to change their speed or lane position.  These are areas where drivers need to pay special attention and work together with fellow drivers.
  • This I-35 corridor also has a high percentage of commuter traffic.  Commuters are familiar with the roadway which is a good thing, however, they tend to overdrive in poor weather conditions because they have developed a habit of driving the same roadway at the same speed every day.  When inclement weather hits, commuters need to pay special attention and drive at a safe speed based on conditions.
  • Generally speaking, the more traffic on a roadway, the more crashes that occur.  Similarly, this section of I-35 has the highest traffic volume of similar Interstate roadways approaching Des Moines (I-80 east and west of Des Moines and I-35 south of Des Moines) and correspondingly has higher crash numbers.

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