The Google map must be at least 20 years old because the trunk road
is labelled A102. When the erroneously named M11 Link Road was opened
in August 1999 (if memory serves correctly) the northern section of the
A102 became part of the A12.

The footbridge is long gone and I don't remember it at all even though I
used to drive under it frequently and, when I worked in Dartford, ten
times a week.