A car ploughed through a barrier and plunged front-first onto the approach ramp to a pedestrian subway at the Elephant and Castle on Saturday evening.
The aftermath of the incident, which happened at approximately 6pm, was captured on camera by local resident Graham Neale.
Graham spoke to an eyewitness who said: "I saw it coming down and I pulled my two children out of the way".
No-one was hurt in the crash which occurred at the southern roundabout close to Elephant and Castle Leisure Centre.
The timetable for the subways to be filled in has been pushed back several times and the latest date given in Southwark's corporate plan is January 2008.
Mayor of London Ken Livingstone has denied claims that Transport for London has held up the project: "TfL has not opposed Southwark Council's plans to remove the southern roundabout and associated pedestrian underpasses at Elephant and Castle," he wrote in response to a question from Green Party London Assembly member Jenny Jones.
"TfL has been working closely with Southwark Council and its consultants and will continue to do so. Both organisations are working constructively toward a positive outcome."
Speaking to the London SE1 website last month, Southwark Council leader Nick Stanton insisted that the removal of the unpopular pedestrian subways is "an intrinsic part of the regeneration" but explained that as a London Development Agency-funded project on Transport for London-controlled roads, "it's not one of those things we [Southwark] can get on with on our own".