will I caught in the highway traffic jam from shanghai to suzhou on 28 Apr or 2 May 2013?

I can't decide which date should i travel to shanghai for suzhou, as understand the labor day golden wk start from 29 Apr to 1 May(official holiday) and would like to avaid being caught in heavy traffic jam. need some advice...will the ppl there start travel out/in shanghai on sat/sun (27/28 Apr) and continue till 2/3 May? What to look out for? thanks