Unifying Alabama's Traffic Safety Efforts
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Weather


Click Here to View the CAPS Analysis of Weather in Alabama 2012 Data

This page is dedicated to studies and information related to severe weather impacts on communities, including transportation, economic, and civil impacts. The winter weather impacts of the 2014 season have created multiple complications for the public, schools, and businesses in many regions of the country.
Voluntary Exposure Benefits and the Costs of Climate Change
Understanding the channels by which climate change will affect the economy is required to estimate the costs of climate change and to develop adaptation strategies. Extreme heat may result in direct costs such as increased mortality from heat stress and lower productivity.

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Effects of Weather on Crash Severity

What is the effect of weather on crash severity? The cross-tabulation below shows how weather is a factor. The yellow cells are just above average, which might not be significant. The red cells are greater than 10% above average, which is probably quite significant if the numbers in the cells are greater than 30.  It seems that the big killer on this chart is fog.  One theory is that in Alabama, fog is spotty and many drivers just cruise along at high speeds and stumble into the fog.   On the other hand, rain is significantly under-represented in the higher severities for the opposite reason, people usually slow down in the rain and very few speed up.

2012 Alabama Integrated Crash Data



For a review of how rain increases crash frequency as well as several other weather-crash details, see: The Effect of Weather on Crashes

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Safety Impacts of Reduced Visibility in Inclement Weather
The Atlas Center: Visibility conditions at the time of a crash are rarely documented at a high level of detail. While vision is a key component of how drivers acquire information, a direct relationship between quantified levels of visibility related issues and safety (in terms of crashes) should be identified.

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Alabama Crash Analysis of the Last Week of January 2014
As part of the Center for Advanced Public Safety (CAPS) at The University of Alabama's ongoing studies to improve traffic safety in Alabama and the nation, a study was conducted to focus on the dramatic increase in crashes that occurred in Alabama as a result of the rare ice and snow storm that occurred beginning early on Tuesday, January 28th and continued throughout the day. Traffic was affected for most of the rest of the week.

In order to keep the difference between weekday and weekend traffic from creating a complicating factor, the entire last week (seven days) of January in 2013 and 2014 were used to make the comparisons. This would then account for the changes in traffic flow that might have resulted from the pre-storm warnings as well as the aftermath of the storm itself.

The following gives an overview comparison of the number of crashes by severity for the two weeks being compared:

Severity

Jan. 25-31, 2013

Jan. 25-31, 2014

Fatal

14

12

Severe Injury

251

216

Possible Injury

178

201

Property Damage Only

1479

1921

TOTAL

1922

2350


The increase in the total number of crashes was quite significant, at 22%. However, this increase came totally from the lower severity crashes. Both Fatal crashes and Severe Injury crashes decreased (a combined 14% decrease). This is not unusual in weather-related crashes in that most motorists have the training and common sense to slow down when the pavement is slippery. In some cases around the urban areas the traffic came to a standstill or was greatly impaired forcing drivers to slow down.

Crash density maps were developed to provide a feel for the general location of the crashes, especially as they relate to the Interstate highways and the large cities. The first map below shows the overall crash density for the storm week. A comparison of this with the comparable 2013 map showed no significant differences, essentially establishing that the crash density effects of the storm were about the same statewide.