A-road gantry sign
A gantry structure spanning the road with overhead green signs showing an exit and the following text.
Forward destinations: (M11, M1) Stansted [Airport symbol] A282 (M25).
Left turn destinations: Swanscombe, Erith A206 [Hollow diamond diversion symbol] [Solid circle diversion symbol].
Junction number: 1A.
This looks like a local junction, and it is, but it's also surrounded by surprising numbers of commercial and industrial buildings, occupied by businesses that find it convenient to be right by the river and the M25.