A $30 million upgrade to a section of the M4 motorway near Parramatta dubbed "crash alley" will be fast-tracked after a review found it still has a high number of crashes despite recent improvements.

Irish tradesman Francis Shanley, 36, was killed in a multi-vehicle crash on the M4 on May 9 near the eastbound off-ramp at Church Street. Mr Shanley's ute was one of 11 vehicles which collided after braking heavily to avoid a car that had stopped on the M4 at the Church Street off-ramp.

The plastic barrier introduced at the black spot has led to fewer crashes, but the off-ramp is still regarded as a "death trap". Credit:Wolter Peeters

The Church Street off-ramp is the last exit before eastbound traffic passes a toll gantry and enters the first stage of the WestConnex toll road between Parramatta and Homebush.

A six-month upgrade was originally earmarked to begin late this year but the government announced on Wednesday that work will start this month to ease queuing on the exit ramp.