The A419 is now open in both directions after Highways England managed to clear extensive flooding.
Police shut both carriageways at the South Cerney turn-off last night after flooding and a series of crashes brought traffic to a standstill.
The road was reopened at around 3am.
The flooding came as the country was battered by Storm Brendan yesterday.
A yellow weather warning for rain remains in place for the south coast this morning.
The Met Office forecasts sunnier weather for Swindon today, although there will be a return to heavy rain on Thursday.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here