People heading west on the M27 were told to expect diversions from junction 1 at Cadnam through to the Ashley Heath junction on the A31/A338 near Ringwood.
Motorists have been forced to divert this week from 8pm until 6am with traffic redirected via the A336, A326, A35, A3060 and A338. Today is the final day of closures this week.
The stretch will also be closed eastbound towards Southampton for five consecutive nights – but those dates have yet to be confirmed.
The closure is so drainage work can be carried out overnight, National Highways said.
National Highways removed the east section of the bridge carrying the A31 over the River Avon last week.
The large 750 tonne crane was returned to site last Wednesday before work to begin removing the bridge beams started the following day.