AASHTO LRFD Bridge Design Specifications – 2008 Interims Released

April 7-11 is National Workzone Awareness Week (NWZAW) which draws attention to the hazards roadway construction crews face from motorists not heeding safety warnings. For 2006—the last year for which data is available—more than 1,000 died in work zones. Figures for 2007 will be released by the National Work Zone Safety Information Clearinghouse later this year. Motorists are also at risk for not following work zone safety precautions. They may face damage to their vehicles, injuries, and loss of life. For 2006, 614 motorists died in work zone crashes. (Graphic by Caltrans)

Below are a few items to think about the next time you’re driving through a workzone taken from a Caltrans fact sheet. More after the break (sorry for the “Duh” ones, but I didn’t write them). As someone who occasionally works on the road and knows many more people who do, please, please remember to slow down!

• Most injuries and deaths in the Cone Zone are from rear-end collisions.
• If you slow from 65 to 55 mph for one mile, you only lose 10 seconds on your travel time.
• The first cause of death for people aged 16 to 20 is car crashes. Even if you don’t lose your life causing a car crash, it could still cost you your license or a heavy fine.
• If a car’s speed is doubled, the stopping distance is doubled twice over. For example, if a car traveling at 30 mph requires 100 feet to stop, the same car at 60 mph takes not 200 but 400 feet to stop.
• At 60 mph, you’re traveling 88 feet per second. A lot can happen in one second, so give yourself plenty of room to stop in case of an emergency.
• For the 15,000 miles of California highway Caltrans maintains, it must buy 120,000 new cones every year to replace ones run over by careless drivers.

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The much anticipated LRFD update to the MSE Wall and Reinforced Soil Slope Manual is now available for download from the FHWA’s website. The full title of the document is Design of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes and it was authored by Ryan R. Berg, P.E.; Barry R. Christopher, Ph.D., P.E. and Naresh C. Samtani, Ph.D., P.E. Find the abstract and download link below. As time permits, I’ll try to post more about some of the changes in this important geotechnical publication.

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Drilled shaft foundations as well as retaining walls such as tangent and secant pile walls typically have a verticality requirement as part of the specifications. These requirements ensure that the moments and stresses in the […]