And thanks to the help of a local man, engineers were able to shorten the time taken on testing.
Robin Atkinson, a Fellow of the Institution of Structural Engineers and the Institution of Civil Engineers, created a computer model of the bridge that showed how it behaved in certain conditions.
Marlow Bridge, which opened in 1832, was substantially rebuilt in the 1960s and strengthened with longitudinal girders.
Mr Atkinson said these saved the bridge from more damaging stress than might otherwise have been caused by the 37-tonne lorry.
Simon Dando, Transport for Buckinghamshire's contract director, said the engineers' team was indebted to Mr Atkinson.
He said: "Access to this modelling helped us pinpoint the areas we needed to inspect and test."
Bucks County Council (BCC) chairman Val Letheren invited the town mayor, Bob Johnson, to join her to become the first car to drive across it since September 24.
Mrs Letheren drove the mayor after the cut the ribbon to celebrate the reopening.
Mrs Letheren said: "This is a great day for Marlow residents and traders.
"I'm so pleased we've been able to open the bridge in time for the Christmas shopping period."
Mr Johnson said: 'I'm pleased that such extensive testing has shown our bridge is safe. Now we can get on and encourage people back to shop local in Marlow and make it a bumper Christmas for the town.'
Mark Shaw , BCC cabinet member for transport said: "The bridge is very special to the people of Marlow and Bisham.
"I'm very grateful for the utmost care our engineers have taken with their tests, which I know is exactly what people would expect of us.
"I'm sure today's opening is the best present we could have given the people of Marlow for Christmas."
The cost of the five weeks of inspection is expected to run into tens of thousands of pounds.
According to Mr Shaw this will be covered by the insurers of the Lithuanian haulage company, Girteka, whose lorry crossed and broke the bridge.
Engineers say the three-tonne weight restriction will remain, and recommend replacement of one of the suspension hangers and pins supporting the approach road deck.