In 2008 the route between J11 and J12 near Portsmouth was expanded to reduce congestion on the route and making driving safer.
But Freedom of Information figures obtained by Hampshire Constabulary show that on average, there have been more major collisions since the change was made to both sides.
From January 1 2000 to August 31 2008 there were 157 collisions with injuries reported - an average of about 18 a year.
But between September 1 2008 and May 31 2016 there were 163 collisions reported, increasing the average to 21 a year.
The highest amount of injury collisions reported on the road was in 2012 with 30.
During the last 16 years there has also been four fatal collisions on the route, in 2004, 2006, 2007 and 2013.
A spokesman for Highways England - who bought in the scheme- said: ‘The improvements between junction 11 and 12 have reduced congestion and improved journeys for the 120,000 daily journeys on the M27.
‘Safety is Highways England’s top priority and we remain committed to reducing the number of people killed or seriously injured on our roads.
‘We will continue to keep safety under review, working with partners such as the police to understand what can be done to improve safety.’
*Do you usually drive on J11-12 on the M27? Do you feel safer driving when there are four lanes? Let us know by emailing [email protected] or commenting on our Facebook page.