In December 2007 a 15-month, $5.5 million project was completed to add fourth (or "operational") lanes in each direction between the entrances and exits at Exits 10 and 11 in Darien. An earlier project added a fourth lane on the southbound side from the entrance at Exit 10 to Exit 8. After that lane was added, a state Department of Transportation study concluded that accidents were down on that stretch of the highway by 20 percent, amounting to about 160 fewer accidents per year.