I am indebted to one of our members, David Baker, for supplying me with copies of two articles that appeared in the Bath and Wilts Chronicle - the first dated March 7th 1934; the second undated, but probably within a few months of the former. They give, in quite graphic detail, a description of the work involved in the replacement of one of the river bridges on the outskirts of Bath - Tony Wray.
Background
Up until 1930 the bridges on the Bath branch could handle only light locomotives - the 4-4-0 Compounds being the heaviest engines able to traverse the line from Mangotsfield.
With the planned introduction of the Stanier Class Five 4-6-0's as the mainstay of the line's expresses, a massive rebuilding programme was undertaken throughout the 1930's, culminating just before the outbreak of World War Two - a lucky piece of timing as the branch (and the Somerset and Dorset) was often used for troop trains during the hostilities.
To start with the road bridges were replaced, followed in 1933 by a contract which was signed for the six large river bridges which existed between Bitton and Bath. As can be seen from the following news cuttings, the work involved replacement of the original ornate Midland Railway lattice girder bridges with more modem steel girders.
This work was undertaken on all but the final bridge into Bath station itself - it was felt with the low speed that trains would be travelling over this bridge that strengthening in the form of additional welding of the latticework would suffice, this having a further advantage of not disrupting traffic on this very busy section of line.
In addition to the replacement of the girders, the original ten cast iron columns (or screw piles) that formed the central pier were replaced by a large, concrete pier - this work taking place at all six river bridges, including the one at Bath station.
Only one of the original lattice girder bridges now remains on the former Mangotsfield to Bath branch - the one just outside of Bath Green Park station, now carries cars into the Sainsbury supermarket. The adjacent bridge (there were four tracks at this point) was removed sometime between 1966 and 1968. Although this bridge was not replaced, the cast iron columns that originally supported it centrally were removed in favour of a concrete pier.
As detailed below, work began on bridge 35 on the outskirts of Bath. In order not to disrupt traffic single line working was introduced over that line which was not having its girder section replaced - this work being controlled by a temporary signal box which was erected at various points along the lineside as work progressed - 'Rudmore Park' (referred to in the second article) being opened from 29th April to 2nd September 1934.
The next river bridge towards Bitton (No. 28) was tackled during 1935, followed by Bridge No.40 in the city itself, then the River Avon bridge (No. 19) in 1937, with Kelston bridge being replaced in 1939 thus bringing to an end the work which then allowed all but the heaviest engines to work into Bath, and consequently over the Somerset and Dorset to Bournemouth.
New bridge for old, reconstruction work near Bath
LMSR enterprise
A Transformation scene has been in progress for some time just on the outskirts of the Bath boundary. It is a transformation belonging to the engineering world, and not to the theatrical stage, and the task in hand involves the replacement of the two-span under-bridge which carries the Bath branch of the LMS Railway over the Avon a short distance on the Bristol side of Weston station.
This renewal is part of a scheme for the reconditioning of all the under-bridges on the Mangotsfield to Bath branch. In this comparatively short piece of line, the Avon is crossed no fewer than six times. The structure which is now being dealt with is known officially as 'Bridge No. 35', and in a few months time this will be entirely renewed with a minimum of delay to traffic. At no time during the reconstruction will the working of trains be entirely suspended.
Bridge 35, near Newbridge, Bath, pictured in 1995. This shows the new 'modern' steel girders, and the concrete central pier that replaced the original ten cast iron columns. Immediately north of here is where the Avon Valley Railway hope to build a new station on the outskirts of Bath, giving us a six mile long preserved railway from Oldland Common to Newbridge. Photo - Tony Wray.
So far the work has provided no spectacular features of a character likely to cause the speeding motorist to turn his head as he flashes by, or the crew of the racing eight out for a practice row on the river to lose time as they pass under the structure. But an inspection of the work in progress and a description of the objectives of the engineers arouse admiration of the carefully planned sequence of operations.
Widening work
The new bridge will be somewhat wider than the existing structure, which was built over 60 years ago, and one of the first essential preliminaries in the direction of reconstruction has been the widening of the masonry abutments on the banks on either side.
The contractors, a Staffordshire company, have established a little colony of workshops in the neighbouring meadow, with all the necessary equipments of a line of portable railway and a temporary sleeper track to enable road vehicles to approach from the Lower Bristol Road, which runs close by.
Like the present structure, the new bridge will be of the girder pattern, but the old lattice girders will be replaced by the more modern plate type. Mr. J A Huston is the engineer-in-charge of the work on behalf of the contractors.
The rebuilding scheme provides for the retention of a central pier in midstream but the constructional method will be considerably modified in accordance with more modem principles. The group of ten cast-iron columns or 'screw piles' are to be replaced by a single concrete pier.
Triple operation
Three distinct processes are involved in this work of replacement. The first essential is the temporary substitution of steel columns or 'trestles', which will support the river ends of the main girders while the concrete pier is being built up into place. The removal of the original cast-iron columns will constitute the second operation, and the third operation will be the building of the new pier. The new superstructure will then be placed in position in stages.
Each of the existing girders is of 100 feet span; so that the total length of the bridge is 212 feet.
The earlier bridge was constructed at a period when railway engineers introduced more ornamentation into their work than they do today, and the ends of the girders bear scrolls enclosing a lifelike representation of the Wyveryn, that fabulous dragon-like monster which as the heraldic device of Leicester, formed the crest on the coat of arms of the old Midland Railway Company. It was originally the emblem of the Saxon Kingdom of Mercia. For years, like a proud invader, it has challenged the supremacy of the dragon of Wessex.
A period of twelve hours was occupied recently, in unloading from a special train and placing in position the 28 foot steel columns which are to support the river ends of the girders during the building of the central pier. These columns or trestles are to rest in sockets in the concrete foundation which has already been constructed by the aid of a coffer-dan.
Simple procedure
The actual operation was extremely simple. The Engineering Department of the LMR secured occupation of the up-line on the Twerton side for the requisite period. Single line working was instituted between Weston and Bitton as a necessary operating condition, and traffic was worked over the unoccupied line under the supervision of a pilotman.
Wooden 'shear-legs', secured by guy ropes to the side girders of the bridge, and equipped with tackling, were employed to lower the steel stanchions through gaps in the timber flooring of the bridge created by prising up the timbers into their appointed positions in the foundation.
This work was carried out under the supervision of the Resident Engineer of the LMSR, Mr S U Thompson.
Twenty two men were engaged in Sunday's operations, exclusive of the railway company's staff.
Special signalling
When the work of renewal has become further advanced, single-line working will be introduced over the bridge. For this purpose a new temporary signal box, known as 'Rudmore Park', has been erected to the west of the bridge. In due course crossings will be put in to enable the necessary train movements to be performed. Additional semaphore signals have also been installed. It is expected that this new signal box, which contains the latest electrical appliances, including a track circuiting system, will be brought into use in a few weeks time.
The provision of the new box will temporarily divide into two the present section between Weston and Bitton.
Subsequently this signal box will be used elsewhere, as required, for similar reconstructional purposes.
This branch, as already mentioned, is now being relaid with standard rails weighing 951bs to the yard, and fixed in chairs weighing 45 lbs each.
An important effect of this extensive reconstruction will be to render it possible to run heavier locomotives over this branch.
Tale of two bridges, LMS rebuilding near Bath
Girder replacement
Definite progress is being made with the task of replacing by a new structure the two-span LMS bridge on the Mangotsfield to Bath branch, which spans the River Avon close to the Bath city and Newton boundary.
Since this work was last referred to in these columns, single line working has been introduced over the bridge, and all trains cross the structure at a walking pace.
A new temporary signal box, known as 'Rudmore Park, has been erected, dividing the block section between Weston and Kelston into two. The down line over the bridge has been converted into a siding, and here one of the new main central girders, weighing 83 tons is at present awaiting erection.
A signalling diagram (drawn by Doug Edwards) of the temporary signal box 'Rudmore Park'.
Seven timber cradle
This week, one of the two girders on the Twerton side of the river was launched into position. This particular girder weighs 55 tons, and in readiness for its transfer was secured on seven timber cradles' or 'cribs' with metal shoes, running on ball bearings on a temporary railway track.
Owing to the position of the old central lattice girders of the bridge, which still remain in position, it was impossible to use steam cranes for this work, and the girder had to be drawn into position by a hand-operated winch. A steam crane of the breakdown pattern at each end of the girder would have accomplished in minutes a task which necessarily took several hours, but the situation did not allow sufficient space for a crane to operate.
As this bridge is a two-span structure, the girder extends from the river bank to the new central pier of concrete in midstream. The progress of the launching was necessarily slow, in fact, barely perceptible. It was a stately, but not a spectacular, operation.
Travelling gantry
As the girder, moving horizontally, approached its final position, the pier end was secured to a steel gantry attached to a railway wagon which had been ballasted to give a total weight of 17 tons. This wagon was drawn forward simultaneously with the girder by another winch.
This procedure enabled the girder to be kept in a horizontal position as it approached the central pier, and necessarily parted company one by one with its supporting cradles, as the temporary track was not continued beyond the river bank.
The new bridge will be somewhat wider than the old structure, as provision was made for the outside plate girders to be erected outside the old lattice girders. The latter will subsequently be cut up by the oxyacetylene process, and disposed of as scrap metal.
When the girder was in position the remaining task was to lower it on to the pier and abutments. For this purpose a steel gantry was erected on the central and side girders of the original bridge. The total weight of the six main girders of the new bridge, exclusive of the substructure, is 386 tons.
Mr S Thompson, of the LMSR engineering staff, is in charge of the work.
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