The bridge will span the Carpenters Road and will be part of the central pedestrian concourse through the middle of the east London site both in Games time and legacy.
The start of works saw 290 cu m of concrete poured to create the first foundations for the abutments of the bridge.
Once the foundations and bridge abutments are in place, 23 m long steel beams will be lifted into place to form the deck of the bridge which will be operational for construction traffic from November this year.
Britain’s biggest contractor will also begin works later this summer on a huge land bridge that will form part of the roof of the aquatics centre.
The structures, bridges and highways project will see more than 30 bridges and 20 km of roads built in and around the Olympic Park.
The first four contracts under the project were awarded back in January with Balfour Beatty bagging a brace and the remaining two going to Nuttall and Skanska.
Two more packages – Wetland Area Bridges and Central park Bridge – will be awarded by the end of the year.