How busy is that dual carriageway?
This is a crossing point between Wickford and North Benfleet, as is evidenced by the gap in the crash barrier and the encouraging sign.
But of course they've provided a replacement crossing. Oh, no, they haven't.
There are loads of similar "gap in the barrier" crossings, off the top of my head I've used one near Raglan and another on the A40(?) in Oxfordshire, but neither were anywhere near as busy as that Southend road.