It connects the promenade at Richmond with the neighbouring district of St. Margarets on the west bank during the day and is closed at night to pedestrians – after 19:30 GMT or after 21:30 when BST is in use.

Below the structure for a few miles, at low tide, the navigable channel is narrow and restricts access for vessels with the greatest draft.

The middle section has mechanically rising-to-parapet-height sluice gates forming sheets of metals above and close to the water line which is created by these structures when lowered.

The lock and barrages were installed in 1894 by the Thames Conservancy to maintain a broad navigable depth of water upstream of Richmond.

The rising barrage ensures upstream at least 1.72 metres (5 ft 8 in) of water is in the standard navigation channel (away from banks) to the next lock, Teddington, and an annual draw-off (an all-tides lifting of the sluice gates) takes place to enable dredging to keep the advertised 1.72 metres (5 ft 8 in) minimum channel depth.

[6] When the London Bridge of 1209 to 1831 was demolished the removal of its bulky and elaborate piers resulted in the tides upstream returning to the rapid flows as they were downstream and before its forming of a near-barrier.

[7] By the late 19th century water extraction above Teddington had increased to four of five of the city's main waterworks and after light or normal rainfall more barges found it impossible to navigate the reach during and for hours around the two low tides each day.

For about two hours each side of the published time of high tide the three sluice gates are raised into the footbridge supports above, and river traffic can pass through the barrage unimpeded.

The sluice gates were manually operated by lock keepers, who lived in housing mostly contained under the pedestrian steps and landing on both banks.

[1] From the date of the bridge's opening until some time during World War II, pedestrians were charged a toll of one (old) penny, i.e. 1⁄240 of a pound.