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Preston By-Pass
The first length of motorway opened in the United Kingdom.

On the 5th December 1958, Prime Minister Harold Macmillan opens Preston By-Pass, an eight and a quarter mile length of motorway.

At the opening ceremony, Macmillan indicated the significance of the event as follows;

"What Lancashire has today, other parts of the country will have tomorrow",

"In the years, the county and country alike will look at the Preston By-Pass - a fine thing in itself but a finer thing as a symbol - as a token of what was to follow".

The Roadworks
Roadworks

The Bridgeworks
Bridgeworks

The construction of the bridges on Preston By-Pass accounted for approximately one third of the total cost of the contract. Since there was only one junction on the By-Pass, at the point where the motorway crossed the River Ribble and the A59 (now Junction 31), the By-Pass was taken over or under a series of roads, railways, rivers, streams and footpaths. Where the By-Pass divided farmland then occupation bridges were built so that farmers could continue to conveniently use and access their land. A total of twenty three bridges were built for the By-Pass.

A statutory minimum headroom of 16 feet 6 inches (5.03 metres) had to be provided at the bridges under or over the By-Pass. A minimum headroom of 17 feet (5.18 metres) was used throughout the contract. This permitted slight settlement of bridges following construction plus the additional of a small amount of carriageway resurfacing, without the headroom droping below the statutory minimum.

Most of the bridges over the motorway (overbridges) had 4 spans since this allowed a relatively shallow deck to be used which would look light and be visually attractive. If the highway alignment was on a curve then a pier in the central reservation was avoided since it would restrict the vehicle sight lines. Instead a single span or 3 span bridge was designed to work around this.

The bridges under the motorway (underbridges) were normally single span structures since they were generally fairly short spans. The exceptions to this were Samlesbury Bridge over the River Ribble and A59, 3 spans, 120 feet (36.6 metres), 180 feet (54.9 metres) and 120 feet (36.6 metres), total length 420 feet (128.0 metres) and Higher Walton Bridge, 6 spans, 2 end spans at 40 feet (12.2 metres) and 4 interior spans at 97 feet 6 inches (29.7 metres), total length 470 feet (143.3 metres).

Reinforced concrete box culverts were constructed in order for the motorway to cross the small streams on the route. The footbridges that carried public rights of way over the motorway were three pin arches built in reinforced concrete.

Each bridge on the By-Pass.

The bridges are described from south to north along the motorway. All have been modified, replaced or, in some cases, demolished and not replaced. All bridges have a name, often taken from an adjacent geographic feature, and a bridge number. The numerous sign gantries over the motorway were all built as part of the 1997 contrac which widened the vast majority of this length of motorway to 4 lanes in each direction.

Withy Grove Railway Bridge No 5219

The southern most bridge carried the By-Pass over the Preston to Blackburn railway line. The span was increased to allow it to also cross diverted footpaths adjacent to either side of the line. It is a single span structure, span 49 feet 6 inches (15.1 metres) with a precast pre-tensioned beam deck, supported on reinforced concrete abutments and wing walls. This is one of the few structures to remain largely unchanged in over 50 years. The primary modifications over this period have been parapet and safety fence upgrades. Nowadays, this bridge is the first structure that you cross travelling north from Junction 29.

Brindle Road Bridge No 5220

This four span bridge that now takes the unclassified Brindle Road over the motorway, with spans of 35 feet 3 inches (10.7 metres), 55 feet 3 inches (16.8 metres), 55 feet 3 inches (16.8 metres) and 35 feet 3 inches (10.7 metres). The piers and abutments were built in reinforced concrete with a deck of precast pre-tensioned beams. This is another structure that is relatively unchanged over the years. The primary modifications over this period have been strengthened parapets on the overbridge and safety fence upgrades on the motorway.

Lane End Farm Bridge No 5255

An occupation bridge which had four spans, 31 feet (9.4 metres), 48 feet (14.6 metres), 48 feet (14.6 metres) and 31 feet (9.4 metres). The piers and abutments were built in reinforced concrete with a deck of precast pre-tensioned beams and a reinforced concrete slab. This bridge has been demolished and not replaced, perhaps at the time of the construction of Blacow Bridge No 5595 in 1967. Blacow was first built to provide the northbound link from M61 to M6 and was replaced at the time of the 1997 widening of the motorway.

Prospect Hill Bridge No 5222

A single span structure of 94 feet (28.7 metres) which carries C255 Cottage Lane over the By-Pass. The abutments and wing walls are of reinforced concrete with a deck built in prestressed beams with a concrete slab. This bridge was conceived as being one of the structures that would take Preston Southern By-Pass over the motorway. Preston Southern By-Pass was planned to run from the A59 Longton by-pass, approximately 4 1/2 miles to the west, and fifty years later remains unbuilt. The original structure was demolished and replaced by a new structure in 1967.

Higher Walton Bridge No 5224

As mentioned earlier, this is a 6 span structure, 4 interior spans at 97 feet 6 inches (29.7 metres) and a span at either end at 40 feet (12.2 metres), total length 470 feet (143.3 metres). It takes the motorway over the valley of the River Darwen and the A675. The piers and foundations are built in reinforced concrete and the deck is a continuous steel plate girder with a reinforced concrete slab. '''This bridge was widened in 1997 when a fourth lane was added to the motorway. The original piers and foundations support lanes 1 to 4 southbound and lanes 3 and 4 northbound. The east widening supports the southbound hardshoulder and the west widening supports the hardshoulder plus lanes 1 and 2 northbound.'''

Cuerdale Road Bridge No 5226

This bridge took the B6230 Cuerdale Road over the By-Pass and was a 4 span structure with continuous steel plate girders and a reinforced concrete deck slab. The bridge deck was supported by reinforced concrete abutments at each end and the intermediate piers featured tubular steel columns seated on reinforced concrete foundations. The end spans were 48 feet (14.6 metres)and the two centre spans were 68 feet 9 inches (21.0 metres). The original bridge was demolished and a replacement structure built in 1997.

Samlesbury Bridge No 5228

Pope Lane Bridge No 5230

Ribbleton Hall Culvert No 5231

This is a reinforced concrete box culvert which is 5 feet square (1.52 metres by 1.52 metres) and takes Eaves Brook under the motorway embankment. This structure was presumably widened during the works to add a fourth lane in each direction in 1997.

Longridge Road Bridge No 5232

Ribbleton Railway Bridge No 5233

Sandy Brook Footbridge No 5257

A single span, 140 feet (42.7 metres), three pin arch footbridge carrying a footpath over the motorway. The deck was formed in reinforced concrete edge units supporting precast decking units. There were two flights of steps and an intermediate landing to reach the upper level of the footbridge. There are a few remaining similar examples on the M6 both north and south of the original Preston By-Pass, many have been modified since they had insufficient headroom over the hard shoulder and so prevented the temporary use o the hard shoulder as a vehicle lane during maintenance works. This bridge was demolished and not replaced. The public footpath was diverted to the adjacent Grange Footbridge as part of M6 widening in 1997.

Sandhills Farm Bridge No 5234

Newsham House Lane Bridge No 5235

Fulwood Row Bridge No 5236

Fernyhalgh Lane Bridge No 5237

Ladywell Culvert No 5238

Hindley House Footbridge No 5258

Hollins Farm Bridge No 5259

Moss Leach Culvert No 5239

Broughton Hall Bridge No 5240

D’Urton House Lane Footbridge No 5293

D’Urton Lane Bridge No 5291

The Construction Team
The scheme design and supervision was carried out by the County Surveyor's Department of Lancashire County Council, as Agent for the Ministry of Transport.

The Contractor was Tarmac Ltd who carried out the roadworks, they engaged Leonard Fairclough Ltd as a sub-contractor for the majority of the bridgeworks.

The two multi-span steel bridges were built under separate contracts by contractors who specialised in the construction of major steel bridges.

Samlesbury Bridge is a 3 span structure which takes the By-Pass over the A59 and River Ribble at the only intermediate junction on the motorway, now Junction 31. This was built by Cleveland Bridge and Engineering Company Ltd.

Higher Walton Bridge is a 6 span viaduct that takes the motorway over the valley of the River Darwen and the A675. This was built by Dorman Long (Bridge and Engineering) Ltd.

Ribbleton Railway Bridge was built by Leonard Fairclough Ltd for the British Transport Commission to carry the Preston to Longridge railway line over the By-Pass under a separate contract to the rest of the By-Pass works.