Pavement Preservation Journal, Spring, 2012
By Thomas J. Wood
The use of micro surfacing on bridges is a cost-effective method of preventive maintenance that reduces both wet weather crashes and crashes in general, research by the Minnesota DOT shows. It’s expected that this method is a viable option to further improve bridge safety conditions in Minnesota.
These findings were so significant that in November, the study was a winner in the biennial National Roadway
Safety Awards, sponsored by the Roadway Safety Foundation and the Federal Highway Administration.
Historically, the I-94 bridges east of Monticello, Minn., had a higher crash rate than the surrounding highway. The elevated rate could, in part, be attributed to poor geometry. The bridges were on a super-elevated curve over a railway. In addition, the elevated bridge decks allowed the concrete deck to cool off faster than the surrounding pavement, causing bridge decks to become icy at a faster rate than the surrounding pavement.
In 1999, MnDOT applied its first-ever micro surfacing treatment to the bridges and approaches. The bridges were included to evaluate micro surfacing’s effectiveness of reducing both wet weather and typical crash rates. The plan was to use MnDOT’s / International Slurry Surfacing Association Type III aggregate gradation, which is well graded with 100 percent passing the 3/8-in. sieve.