The busy road's being made two lanes in both directions between Segensworth and Titchfield - it's due to take 18 months.
Tickets On Sale For Isle Of Wight Festival
The Stone Roses will headline on the main stage on the Friday.
Meanwhile rock act Bon Jovi are to close the show on the Sunday.
It will be their only UK festival performance of 2013.
Frontman Jon Bon Jovi said his group was `honoured' to playing.
''The Isle of Wight Festival is legendary and we're excited to join in the long tradition of rock'n'roll history ,'' he said.
''This will mark our first visit to the island and I expect it will prove to be a highlight of our tour and of 2013.''
Promoter John Giddings said: ''I can't imagine a better rock band with more hits to close our Sunday night.''
The headline act for the Saturday hasn't been announced yet.
This year, artists such as Bruce Springsteen, Pearl Jam, Tom Petty, Noel Gallagher and Jessie J were among the big-name performers.
There are more details about the event, www.isleofwightfestival.com .
Police want to trace man after 11-Year-Old Approached Near Oasis Academy
Family Appeal Is Shared Online After 14-Year-Old Missing Since Friday
Exceptionally Rare Locker Key Sells For Record Price At Auction.
Recently Played Tracks
Deposit £10 to get a £40 Welcome Bonus - That's £50 to play bingo, slots and more!*
Over 50 tracks to make you feel-good. New album out now...
Find your local four day weather report here.
What's happening on the roads where you are?
Make Heart the soundtrack to your day and you could be a winner with great prizes up for grabs throughout the day.
Find out more about some of the companies advertising on Heart.
Get some great ideas on how to advertise your business on radio, online and on mobile.