Crossing the turbulent tides of the Severn

During his travels, Daniel Defoe finds himself at Aust, awaiting a ferry to cross the Severn Estuary from Gloucestershire, England to Monmouthshire, Wales. He describes the power of the ‘violent’ tides, forcing him and his companions to keep to the road, rather than take the ferry. The last ferry closed in 1966, with two fine road bridges now spanning the turbulent tides at the mouth of the Severn. The second part of this extract describes the challenge of constructing the Second Severn Crossing.

Daniel Defoe prefers the road

As we turn north towards Gloucester, we lose the sight of the Avon, and in about two miles exchange it for an open view of the Severn Sea, which you see on the west side, and which is as broad as the ocean there; except, that you see two small islands in it, and that looking N.W. you see plainly the coast of South Wales; and particularly a little nearer hand, the shore of Monmouthshire. Then as you go on, the shores begin to draw towards one another, and the coasts to lye parallel; so that the Severn appears to be a plain river, or an æstuarium , somewhat like the Humber, or as the Thames is at the Nore, being 4 to 5 and 6 miles over; and to give it no more than its just due, a most raging, turbulent, furious place.

This is occasion’d by those violent tides call’d the Bore, which flow here sometimes six or seven foot at once, rolling forward like a mighty wave: So that the stern of a vessel shall on a sudden be lifted up six or seven foot upon the water, when the head of it is fast a ground. After coasting the shore about 4 miles farther, the road being by the low salt marshes, kept at a distance from the river: We came to the ferry call’d Ast Ferry, or more properly Aust Ferry, or Aust Passage, from a little dirty village call’d Aust; near which you come to take boat.

This ferry lands you at Beachly in Monmouthshire, so that on the out-side ’tis call’d Aust Passage, and on the other side, ’tis call’d Beachly-Passage. From whence you go by land two little miles to Chepstow, a large port town on the river Wye. But of that part I shall say more in its place.

When we came to Aust, the hither side of the Passage, the sea was so broad, the fame of the Bore of the tide so formidable, the wind also made the water so rough, and which was worse, the boats to carry over both man and horse appear’d (as I have said above) so very mean, that in short none of us car’d to venture: So we came back, and resolv’d to keep on the road to Gloucester. By the way we visited some friends at a market-town, a little out of the road, call’d Chipping-Sodbury, a place of note for nothing that I saw, but the greatest cheese market in all that part of England; or, perhaps, any other, except Atherstone, in Warwickshire.

Daniel Defoe, A tour thro’ the whole island of Great Britain, divided into circuits or journies Letter 6 part 2: Oxford, Bristol and Gloucester, 1727 (London: JM Dent and Co, 1927)

Vision of Britain: Daniel Defoe

Second Severn Crossing, opened in 1996

Second Severn Crossing under construction Photo: Dee Holladay
Second Severn Crossing under construction Photo: Dee Holladay

Since before Defoe’s time, there had been ferries across the Severn, but many preferred, as Defoe, to travel via Gloucester rather than brave the turbulent tides.

By the 20th century, it became feasible to construct a road bridge, thus shortening the route between England and Wales considerably for road-users.

The first Severn bridge was constructed in 1966, but by the 1980s it was becoming obvious that a second crossing was needed. In 1992 construction began on a bridge over the shortest and most treacherous section of the Severn Estuary, locally known as The Shoots. This area was well known for tidal streams that vary from 3 to 8 knots and a tidal range of 14.5m. Sailing through The Shoots in the days before powerful engines was especially dangerous, and called for very high level of seamanship. The area is fringed by rocks on each side of the river and known for tricky whirlpools.

It was a hostile place to build, the company paid for two Met. Office staff during the period of the build so they had, in effect, their own weather station, and the decision was made to construct the sections on shore and convey them to their final positions to minimise the work done on and within the river. This approach required the conversion of several suitable large marine craft and appropriate special heavy lifting gear.

The design included a Cable Stayed Bridge over the navigable section, flanked by viaducts largely supported by the existing rocks. The sections of the bridge were constructed on shore and transported out to the river at low tide on crawler units across a specially built causeway to a purpose built barge. At high tide the barge transferred the sections to a fixed crane barge in the river (Lisa A) which lifted them into position when the tide receded. The whole operation of placing the sections of the bridge was guided by a sophisticated computer-operated satellite positioning system. The Lisa A was then floated to the next location and the operation repeated.

The project, led by John Laing plc and GTM Entrepose, opened in June 1996, after a memorable fancy dress charity walk from the Welsh and English sides of the river!

Dee Holladay, OGA Bristol Channel member