New Thames Crossing
These are the options for a potential new river crossing of the Thames (due east of London) as undertaken in a study by Parson Brinckerhoff in January 09 (sourced from londonreconnections.blogspot.com).
The most eastern crossing is located at 'option A', which consists of two tunnels (both northbound traffic) and a bridge (southbound traffic only) - the M25 - London's orbital motorway is connected on either bank. HSR1 (the line connecting London to Paris and the rest of Europe) is visible running along the north of the image (it goes into a tunnel just to the east of the crossing).
At present the traffic jams are severe, and a new crossing is needed to help facilitate free traffic movements, especially when Dubai Port World's new port opens on the north bank of the Thames.
In addition there is a long-term requirement to create a new tidal barrier to protect London from future rises in the sea-level. This is due to the Thames Barrier although ensuring that London is protectd, could become inundated within a few decades, and could be incorporated into a new crossing to protect London into the 22nd century. The scale would be far larger and possibly several km in length.