Diverging Diamond Interchanges Makes Highways More Safe

Friday, June 17th, 2016
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The United States is making its freeways and highways far safer for drivers via the adoption of an innovative new diverging diamond interchange design.

A slew of new studies indicate that the diverging diamond interchange design pioneered by the state of Missouri since the start of the decade is dramatically improving the safety levels of its roads.

America’s first Diverging Diamond Interchange (DDI) was built in Springfield, Missouri back in 2009, with many other US states since following its lead in the adoption of the innovative road design for their own large-scale interchanges.

Traffic experts consider DDIs to be safer than conventional interchanges because they require that vehicles on overpasses or underpasses remain on the left side of the roadway, as opposed to passing along the right lane prior to undertaking large left turns.

This greatly diminishes the likelihood of collision during left turns, which can be a serious problem for standard diamond design interchanges in the United States.

A trio of studies produced by civil engineers from the University of Missouri has since vindicated claims made by traffic experts regarding the heightened safety of the new interchange design.

The researchers analysed over 10,000 crash reports relating to DDIs in both Missouri and other US states and discovered that they dramatically reduce the incidence of vehicular accidents.

According to their research, DDIs achieve massive reductions in crashes, injuries and fatalities. Where adopted, DDI designs have slashed the overall number of crashes by at least half, as well as reduced fatal and injury-causing crashes by more than 70 per cent.

According to Carlos Sun, professor of civil and environmental engineering at the MU College of Engineering, the research finally provides solid evidence of the effectiveness of DDIs when it comes to heightening traffic safety.

“Before our studies little information was available about the safety effects of diverging diamonds,” said Sun. “Two of our research studies analysed several years of crash data and controlled for several variables, including traffic amounts, to account for safety of the interchanges before and after they became DDIs while taking into account DDI ramp lengths, giving us a more complete and robust sample of results that we feel is very comprehensive.”

While Australia doesn’t yet possess a network of freeways and highways on the scale of America’s, the innovative interchange design could becoming increasingly relevant to our own roads in future, particularly given the surging population gains expected in urban areas over the next several decades.

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