A false start
On its completion in 1886, the Severn Tunnel was seen as a successful and lasting solution to the problem of crossing the estuary. However, within a short period the first motor-cars began to appear on the roads of this country and, within a handful of decades, their numbers had increased to the point at which they were causing problems.
Before leaving the historic background to the motorway bridges, it would be fitting to mention a harbinger of the great feats of engineering that would be brought to fruition on the sites of Old and New Passages in the second half of the twentieth century. in 1934, consultants, Mott, Hay and Anderson, acting on behalf of Gloucestershire County Council, sought powers from Parliament to build a bridge across the estuary. It happened at a time when the country was recovering from the impact of the Great Depression, with pressure mounting on highway authorities from groups seeking action to deal with the ever-increasing numbers of vehicles on the nation’s roads. The situation was particularly acute for long distance journeys and the County Councils, who at that time were the highway authorities responsible for major roads, were right in the firing line.
Gloucestershire’s consultants had initially favoured provision of a high level suspension bridge on the Aust-Beachley line, with a 3,000 feet (950 m) span and a conventional truss deck (essentially the same as the initial proposals for the Severn Bridge that were brought forward again in the 1950s). Monmouth County Council had by then joined with Gloucestershire Council and, together, they decided to promote a scheme, three miles downstream from the consultants’ first suggestion. This scheme, across the English Stones, would have been virtually identical to the Second Severn Crossing, except that it had a suspension bridge with a 900 foot (275 m) span, as its centrepiece across the Shoots channel, rather than the modern cable stayed bridge with a span of 456 m (1,395 ft). Also, the spans of the viaduct sections on either side of the central bridge would have been shorter than those on the later Second Crossing.
The two councils launched a Parliamentary Bill to obtain the necessary powers to build this second scheme, assuming that they would be able to persuade the Ministry of Transport to meet 75% of the costs. However, the Great Western Railway opposed the scheme in Parliament, ostensibly on the grounds of potential damage to the Severn Tunnel and, in 1936 a Select Committee of the House of Commons rejected the bill. By that time, the national debate about the management of the major road system was coming to a head and the two County Councils decided to take no further action on a lower estuary crossing until those issues were resolved.
The government was under pressure to change the existing system, with strong evidence from other countries, of the benefits to be gained from the construction of high speed inter-regional roads under central direction. Recognising that the County Councils could not be expected to bear the burden of financing a new national highway system, the Ministry of Transport concluded that a Trunk Road Network should be created and that it should be administered, financed and maintained by Central Government. This change was enacted through the passage on to the Statute Book of the Trunk Roads Act, 1936. The defined network included a Severn Crossing and an improved A48 road along the South Wales coast. However before any significant progress could be made, the Second World War intervened.