Some 46 footbridges are needed to link the Olympic Park with surrounding infrastructure. Some would be substantial structures, including an 80m wide, 250m land bridge with spans of 50m to 60m carrying people between the main Olympic Stadium and the two railway stations at Stratford.
There would also be a 350m long footbridge across the busy A12 and the River Lea.
By no standards could these be described as small structures, as they would carry large numbers of people to and from the Games site.
The Stratford land bridge is designed to carry up to 50,000 people per hour over the River Lea. It also incorporates trees and vegetation to increase the parkland feel of the area, so that most people will have no idea they are on a bridge.
Land bridges comprise groups of trussed, longitudinal steel beams supporting a concrete deck. Steel has been chosen because it is relatively light and quick to position. This is especially important for those structures that cross railway lines or busy roads.
Designers working for Buro Happold have been conscious of the need to reduce the shading impact of such large bridges on the river banks below. As a result the large land bridges incorporate light wells and reflectors to feed some natural light down to the flora and fauna underneath.
The impact of the largest bridges would be reduced after the games by removing sections.
Others would be temporary and removed after 2012.
These measures acknowledge that the Olympic Park would not attract the same volumes of people after the Games because the capacity of the main stadium would be cut from 80,000 to 20,000 and other venues dismantled and relocated.