Ashburton District Council spokesman Jim Henderson told Phill Hooper on Hokonui Mid-Canterbury Breakfast testing the bridge had been a "lengthy process" and it eventually reopened at 11.20pm.
He warned motorists taking the alternative route while the bridge was closed to look out for large potholes and be aware of one-way bridges. People were advised to travel at 60km/h because the route may be unfamiliar to them.
Drivers reported slumping on the deck at the Ashburton end. A damaged pier had sunk around 150mm during the weekend floods.
Waka Kotahi system manager Pete Connors thanked bridge users for their patience while essential, precautionary load-testing was done and asked people to take it slowly on all local roads in coming days.
"Many roads will need patching and repairs after being under water and damaged by debris for 48 hours. There will be temporary speed limits in several places around the Canterbury region while crews catch up with that work."
Motorists are being advised to plan their days accordingly. Alternative route details can be found on the council's website.
After the Ashburton Bridge closed yesterday people were taken by helicopter over the river from Ashburton Airport to the domain at Tinwald to transfer themselves and supplies.
Rain drenched the region and caused major flooding over the weekend.
Ashburton Mayor Neil Brown initially thought it would take more than a few days to fix.
Digbys Bridge on the Asbhburton Staveley Rd is also closed because of flooding.
Meanwhile, a number of roads in Canterbury were still closed on Monday morning.