Actual conditions and operations
Verifying treatment recommendations against actual operations is dependent on two
factors: (1) how close the forecasted weather and road conditions match observed
conditions and (2) how well the rules of practice match DOT operations. Fig. 11.20
illustrates how well the MDSS verified against actual observations and operations. The
forecasted precipitation was fairly close in duration and strength, although the forecast
started the precipitation sooner. Road temperatures were also fairly close, although the
RWIS in-road sensors tended to show slightly warmer roads overall and warm roads in
the pre-storm environment. Post-event discussions with Iowa DOT indicated that they
expected that the roads would be fairly warm throughout the event, therefore, they
performed an initial treatment of chemicals followed by a series of plow-only operations.
As shown previously, the treatment recommendations were fairly sensitive in this case to
the borderline road temperature regime. The fact that overall road conditions were
warmer than forecast would have likely resulted in more plow-only recommendations
from MDSS. The application of freeze-point thresholds will be looked at further for
Fig. 11.20. March 15-16 weather and treatment verification.