Fig. 11.22. Forecasted precipitation, road temperatures and treatment recommendations
for I35N (Ames) during January 25-26.
11.3.3.1
Actual conditions and operations
As shown in Fig. 11.23 the actual levels of snow activity were fairly heavy at the start of
the storm (in terms of snow accumulation, but remember the snow to liquid water
equivalent for this case was quite high, roughly 20:1). Fig. 11.24a shows a picture taken
by an MDSS observer on nearby US30 early in the morning of January 26. Snow is
falling at a moderate pace and is accumulating on the road surface. I35N has the
advantage of having a more elevated deck that was perpendicular to the strong winds
allowing snow to blow across the road surface quite readily. Observer notes from this
period indicate the I35N was blowing clear during much of this period. Road
temperatures verified quite well for this storm. Although the RWIS road temperature is
missing at the very end of the period, trends in the RWIS data just prior to the missing
data indicate it in all likelihood would have verified against the <14 F forecast.
Ames supervisors indicated that this storm presented a tough choice between chemically
treating and just plowing. Ames maintenance vehicles spent the first 8 hours patrolling
and monitoring road conditions. After 0800, Ames began treating but typically only
treated the southbound lanes of the I35 route. Winds were blowing the snow across the
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