Motorists endured lengthy tailbacks as bridge works which will span several months began at Guardbridge.
Drivers reported being stuck in queues for 30 minutes on the A91 between St Andrews and Dundee on Monday.
Fife Council apologised for the lack of warning about the disruption as it repairs arches at the New Bridge over the River Eden.
The road has been reduced to a single lane at the bridge for the initial mobilisation phase of the project by contractor Castle Group Scotland Ltd.
It is not yet clear how long the lane closure will be in force.
Stagecoach East Scotland said its X59 and X24 services were held up and motorists complained that traffic was queued back to Leuchars and Kincaple.
Due to road works in Guardbridge all X59 and X24 services are being delayed up to 30 min.
— Stagecoach East Scot (@StagecoachEScot) June 24, 2019
The council apologised to the community for short notice of the works.
It said concrete repairs will be made to the underside of the arches, with cathodic protection installed to prolong the lifespan of the bridge.
The lane closure, between 9.30am and 3.30pm, is in place to allow the erection of a large scaffold under the bridge. It will be repeated when the scaffold is removed.
Two-way traffic flow will be reinstated during the works, with a temporary 20mph speed limit.