A Watching Brief at the Free Bridge, Jackfield, Shropshire
CONTENTS Page No SUMMARY 2 1 INTRODUCTION 2 AIMS AND OBJECTIVES 3 THE HISTORY OF THE BRIDGE by Dr P A Stamper 4 THE PHOTOGRAPHIC RECORD by Dr P A Stamper 5 THE WATCHING BRIEF 6 CONCLUSIONS 7 REFERENCES AND SOURCES CONSULTED 8 ACKNOWLEDGMENTS APPENDIX I - INDEX OF SELECTED PHOTOGRAPHS
ILUSTRATIONS Fig. 1: Location of Study Area
1 A Watching Brief at the Free Bridge, Jackfield, Shropshire
1 INTRODUCTION The area of the crossing of the River Severn at Jackfield by the B4373 road linking Ironbridge and Broseley was one of the earliest crossing points of the river in the Gorge prior to the construction of the Iron Bridge. The crossing was by ferry, and a number of timber-framed buildings occupied both sides of the river in the vicinity. Tramways and wharves servicing the industry of the Gorge also lined both sides of the river in this area.
Construction work on a new bridge across the River Severn at Jackfield began in June 1993. The existing bridge had been built in 1909 to provide the first toll-free crossing of the River Severn. The bridge was of considerable significance in engineering terms, being a fine example of Mouchel- Hennebrique ferro-concrete construction. However, corrosion and overloading had caused such structural damage to the bridge that a replacement was considered necessary.
In view of the archaeological and historical significance of the area, it was decided that an archaeological watching brief would be required on the initial groundworks associated with the construction of the new Bridge, and on the demolition of the old Free Bridge.
2 AIMS AND OBJECTIVES A brief for the recording of the Free Bridge was prepared by M D Watson, Head of Archaeology, Leisure Services Department, Shropshire County Council.
The recording and watching brief was required to comprise a number of different elements:
Documentary and Historical Research: A search of all the relevant documentary sources was to be undertaken; this research would include the cartographic and aerial photographic sources for the study area, and the primary and secondary sources held at the County Sites and Monuments Record and the County Records and Research Unit.
Photographic Record: A full photographic record was required of the existing Free Bridge both before and during its demolition, to include both general views of the bridge and its setting, and detailed photographs of structural and architectural features.
Watching Brief: An archaeological watching brief would be maintained during all the initial groundworks associated with the construction of the new bridge. Any archaeological features or deposits encountered during the course of these works would be investigated, and a full written, graphic, and photographic record would be made of the findings.
The Archaeology Service of the Leisure Services Department, Shropshire County Council, was commissioned by the County Surveyors Department to conduct this watching brief.
2 A Watching Brief at the Free Bridge, Jackfield, Shropshire
3 THE HISTORY OF THE BRIDGE The history of the bridge is well known, and a useful synopsis is provided in Clark 1989, pp. 16-24 (copy appended). Also known as the Haynes Memorial Bridge and the Subscription Bridge, the Free Bridge was built across the Severn in 1909. It was the first toll-free crossing of the river.
The bridge was constructed using the relatively new Hennebique-Mouchel ferro-concrete technique, an attractive option because of its low cost. The design was by L G Mouchel and partners (copies of original drawings appended), the final version having a central arch of 87 feet with two smaller side spans each of 66 feet and with a clear 25 feet between normal water level and the underside of each arch. The bridge was designed to take a load of 140 lbs per square foot.
Maintained initially by Wenlock Borough, the Free Bridge was transferred to Shropshire County Council in 1937. Inspection of the bridge at that date revealed crumbling concrete and exposed reinforcing. Repairs were done using the Guniting system, new mesh was added to hold additional concrete, and a 12 ton, 5 miles per hour weight and speed limit was imposed. Later, regular repairs to the parapet were necessitated by traffic damage, while in the 1960s polyester bonded concrete (Certite) was used for repairs including a major compression failure in a vertical spandrel strut in 1969. The weight limit, already reduced still further to 10 tons, was finally lowered in 1986 to 3 tons. In the same year, in order to regain the 10 ton ceiling, a Bailey bridge was placed over the existing structure, and that remained in use until the bridge's demolition in 1993.
4 THE PHOTOGRAPHIC RECORD Black and white photography was done both with a medium format Zeiss Bronica ETRS camera and with 35mm Pentax K1000 system. Film stock was mainly Ilford FP4. Colour transparencies were taken on the same 35mm system. The film stock was Boots own brand colour slide film. A selection of black and white prints and copy slides were supplied to the client, to the National Monuments Record (England), to the County Sites and Monuments Record, and to the Ironbridge Gorge Museum Trust library. The main archive of negatives and slides is held by the Archaeology Service.
5 THE WATCHING BRIEF On each side of the river, the groundworks initially comprised the preparation of the ground surface for the erection of a temporary bridge about 20m to the west of the old Free Bridge. This involved the removal of topsoil and some subsoil from the banks and the excavation of pits for the concrete abutments of the temporary bridge. The abutment pits were first sheet-piled and then excavated, affording minimal opportunity for observation of these excavations.
On the south side of the river, the removal of topsoil revealed substantial dumped deposits of cinders and blast furnace slag mixed with some mid twentieth-century building debris around the abutment of the Free Bridge and 3 A Watching Brief at the Free Bridge, Jackfield, Shropshire against the Broseley road. These dumped deposits tailed away towards the river to reveal a dump of mixed clay immediately to the west of the existing bridge abutment and brown silty sandy alluvium over the rest of the waterfront area. The removal of topsoil also revealed the top of a wall set into this alluvium and running parallel to the river about 4.5m back from the water's edge. A short section of this wall could be seen immediately to the west of the construction site, with its northern face exposed. The wall was of drystone construction and built of rough limestone blocks and cobbles. About 9.5m length of wall was exposed within the site running towards the Free Bridge. The insubstantial nature of this wall precludes its having had any structural function, other than possibly acting as a retaining wall along the river bank; it may however simply have been a boundary wall. It is likely that the construction of the Free Bridge would have removed any further easterward extension of the wall.
The top of another stone wall was visible running along the river edge just below the summer water line on the west side of the Free Bridge. The wall was built of blocks of what appeared to be a hard conglomerate stone ranging in size from about 0.25m x 0.25m to massive blocks over 1m3. Again in the vicinity of the Free Bridge, this wall appeared to end, and at this point there were a number of displaced stone blocks in the river. A section of this wall was disturbed by the construction of the abutment of the temporary bridge, and it was again encountered by the contractors during the piling for the abutment of the new bridge. This wall probably represented consolidation of the river edge, pre- dating the construction of the Free Bridge, at the approaches to the Jackfield wharfages to the east.
No other archaeological features or deposits were observed on this side of the river.
The removal of topsoil on the north side of the river again revealed dumped deposits of cinders and slag. The abutment for the temporary bridge was cut straight down through these deposits, and there was no opportunity to observe these excavations, which were carried out within a confined area surrounded by sheet-piling. The contractors did, however, report having encountered a stone wall whilst installing the sheet-piling.
The construction of the abutments of the new bridge involved the excavation of sheet-piled coffer dams around bored concrete piles; these excavations confirmed the nature of the ground on both sides of the river as observed earlier in the construction programme, but revealed no new archaeological features or deposits.
With the exception of the stone walls encountered during the construction of the temporary bridge, no significant archaeological features or deposits were observed during the construction works. Both banks of the river were the repositories of considerable quantities of dumped industrial waste.
During the demolition of the Free Bridge, a number of constructional features, particularly of the reinforcing of the bridge, were recorded in the photographic 4 A Watching Brief at the Free Bridge, Jackfield, Shropshire record. One item, recovered by the Resident Engineer's team, was a "turn buckle", or "tapped socket pipe" as it was referred to on the original working plans (Mouchel and Partners, 1908, 2439 Working Plan No. 7), an uncommon structural element used to connect reinforcing rods (J Fisher, pers. comm.); this item has been kept as part of the site archive. (See Appendices I and II)
5 A Watching Brief at the Free Bridge, Jackfield, Shropshire
6 REFERENCES AND SOURCES CONSULTED Blackwall, A: Shropshire Bridges, Shropshire County Council (County Surveyor's Department Bridges Section Technical Library, ref. no.: 11.1.38) Blackwall, A, 1973: "Maintenance of an old concrete bridge", Concrete No. 12, Vol. 7, December 1973. p26 Brear, B, 1909: "The New Ferro-Concrete Bridge at Ironbridge, Coalbrookdale", Ferro- Concrete No.1, Vol. 1, July 1909, pp19-23 Clark, C, 1989: Archaeological and Historical Issues Relating to the Proposed New Road Bridge at Ladywood, Ironbridge, Ironbridge Institute Research Paper Clark, C, 1990: Application by Shropshire County Council for a Proposed New Road Bridge at Ladywood, Ironbridge, Telford. Archaeology and History. (Agreed Statement 4) [at Public Enquiry] Clark, C, Winkworth, A, and Worthington, M, 1990: Ladywood Bridge Site, Ironbridge, Telford. Excavation and Further Documentary Research. Ironbridge Institute Research Report 56 Gifford Consulting Engineers, October 1991: Free Bridge, Jackfield: Proposed New Bridge, Report 4796/02/01 L G Mouchel and Partners, 1909: Hennebique Ferro-Concrete: Theory and Practice: a Handbook for Engineers and Architects Highways and Transport Department, Shropshire County Council, April 1989: Proposed Bridge at Ladywood in the Ironbridge Gorge: Environmental Statement W H Thomas and Partners, March 1986: Free Bridge, Jackfield, Telford, Shropshire: Condition Report and Loading Assessment
Photographs in Ironbridge Gorge Museum Trust collections: IGMT 1984.6054 The Free Bridge under construction 1908 IGMT 12986.6325 "The New Free Bridge, Iron Bridge 1909" Postcard IGMT 1980.1644 or "The Free Bridge, Iron-Bridge" 1910-1915 Postcard 1982.1872 IGMT 1980.1646 "The Free Bridge, Ironbridge" 1930-1940 Postcard IGMT 1982.1541 The Free Bridge During Floods 1946 IGMT 1980.1645 "Ironbridge, The Free Bridge" 1950-1960 Postcard IGMT 1984.6341 Aerial view of the Free Bridge
6 A Watching Brief at the Free Bridge, Jackfield, Shropshire
7 A Watching Brief at the Free Bridge, Jackfield, Shropshire
8 A Watching Brief at the Free Bridge, Jackfield, Shropshire
APPENDIX II
INVENTORY OF DOCUMENTATION RELATING TO THE CONSTRUCTION AND REPAIR OF THE FREE BRIDGE
1 The original designs for the bridge are still held by L C Mouchel and Partners, West Byfleet, Surrey.
L. C. MOUCHEL AND PARTNERS LTD., BRIDGE OVER RIVER SEVERN, JACKFIELD, 2439
Plan No. 2 4th May 1908 Working Plan (Elevation and Cross Section) Plan No. 4 20th July 1908 Working Plan Plan No. 6 14th October 1908 Working Plan (Plan of Piles) Plan No. 7 5th November Working Plan Plan No. 8 25th November 1908 Working Plan (Radii of Arches) Plan No. 9 23rd December 1908 Working Plan (Half Elevation) Plan No. 10 4th December 1908 Working Plan
Sketch E 22nd September 1908 Sketch G 8th October 1908 Dimensions of Arches Sketch R 18th November 1908 Elevation
In addition, the Bridges Section, County Surveyor's Department, have copies of three further Mouchel plans: 1 Elevation/PlanView/Cross Section 2 Half Elevation 3 Details
2 Brear, B, 1909: "The New Ferro-Concrete Bridge at Ironbridge, Coalbrookdale", Ferro- Concrete No.1, Vol. 1, July 1909, pp19-23 Account of the construction of the Free Bridge
3 Wellington Journal and Shrewsbury News, 19th June 1909 Description of method of construction of piles (Clark 1989)
4 The Bridges Section, County Surveyor's Department, Shropshire County Council has files relating to the bridge dating back to 1960. The earlier files do not appear to have survived.
Free Bridge file (B/82). Synopsis of Contents (Nb. first extract correspondence. 8.9.54. Next letter then 2.5.1960.)
2.5.1960 2 handrail stanchions 'rusted clean through' at S. end of bridge at deck level, also the stays. Repair needed.
1.11.1960 Check to see if 12-ton limit is being violated.
15.8.1961 There is a certain amount of cracking and spalling of concrete, exposing some of the reinforcement. Repairs to be undertaken using the guniting process.
10.10.1961 Repair contract awarded to Wm. Mulcaster & Co. Ltd of Crewe.
20.12.1963 Report of Weights & Measures inspector noting the successful prosecution of a driver of an 8-wheeled 21-ton vehicle.
6.4.1965 Duroclay Ltd. ask that weight limit be increased to 14 tons.
19.4.1965 Reply to Duroclay by County Surveyor. Pre-War test using 14-ton vehicle after repairs using Guniting, showed 'signs of stress under the movement of the 14 ton 9 A Watching Brief at the Free Bridge, Jackfield, Shropshire
vehicle'. Since then there has been some deterioration in the structure.
20.12.1971 The 12-ton limit has been in place since 1937. Since then there have been three major overhauls. Gross overloading a problem. Will Madeley UDC agree to lowering of limit to 10 tons? (The proposal is made by Dawley UDC).
25.10.1972 Subject of a replacement bridge is frequently discussed by SCC and TDC. No plans as yet however.
30.10.1972 Road Haulage Association Ltd. Object to proposed 10-ton limit.
10.7.1973 East Shropshire Water Board has a 3" diameter main crossing the bridge.
25.9.1974 [one of numerous reports of traffic damage to bridge. Police appear never to catch culprits]. In this case 12' of parapet railing damaged.
17.2.1977 AB notes the need to replace the complete parapet of the bridge. 'The problem is to devise a practical method of fixing'.
11.5.1977 The bridge has a gross vehicle weight limit of 10 tons, & 5 mph speed limit. Damage especially to parapets, is mainly due to articulated lorries returning empty.
5.11.1980 10-ton weight limit due in past to cracking of spandrel columns. There is a dispensation up to 12 tons for P S Vs due to their longer wheel base and softer suspension.
11.10.1985 Free Bridge designated a Listed Building in April 1983.
Tenders invited from Consulting Engineers to repair bridge and waterproof deck. TDC to part fund work in financial year 1985-86.
4.11.1985 W H Thomas & Partners of Wellington appointed to carry out works on the bridge.
15.11.1985 Scheme to cost £40,000 (SCC contribution £6,800)
28.2.1986 Preliminary findings of structural analysis suggest that parts of the bridge (eg. deck slabs and cross beams) have a car-only load capacity.
4.4.1986 Memo outlining how any collapse might occur (follows receipt of consultant's report)
9.4.1986 Report on council meeting agreeing 3 ton limit plus one way working with traffic lights. Some temporary bracing and strengthening to be put in place. Shropshire Star.
21.5.1986 New limits causing great local problems. New bridge or refurbishing urgently needed.
23.4.1986 Damage to bridge caused by road salts as the bridge was not originally waterproofed.
24.5.1986 Free Bridge inspected 1969 (special investigation); 1974; 1979; 1985
24.5.1986 Provision of a Bailey Bridge on top of the existing structure authorised. Will restore the 10-ton limit.
22.5.1986 Records shows the bridge repaired as early as 1935 [? what records] 10 A Watching Brief at the Free Bridge, Jackfield, Shropshire
13.6.1986 Consultation with DOT re financing a new bridge. Estimated cost £700,000.
4.7.1986 Photo and report on new bailey bridge which opened earlier that week. B'north Jnl
11.7.1986 New bridge opened 1.7.1986.
11.12.1986 'Contract Report' by Thos. Storey Engineers, suppliers of the 67.5m long temporary bridge. Includes good line drawing.
9.10.1987 Detailed design work in hand on the new bridge, to be known as Ladywood bridge. This to be built halfway between the Free Bridge and the Iron Bridge.
5 The following photographs were given to the writers by the Bridges Section, County Surveyor's Department, to be deposited in the collections of the Local Studies Library, Shrewsbury:
(i) Print and negative: HD/13/3 "Slow-up" on Broseley side of Jackfield Bridge. (Rolling tubes since in position). June 1940 (ii) Print and negative: Jackfield Bridge. Cement Gun Co. View from northeast of bridge with scaffolding at southern end. c1935-7 (iii) Negative: Close-up view from northwest of scaffolding at northern end of bridge. c.1935-7 (iv) Print: View from west showing scaffolding and sheared column at north end of bridge. c1935-7 (v) Print: Detail of sheared short column prior to repairs. c1935-7 (vi) 2 prints: The Free Bridge, Jackfield. 1974. View of bridge from northwest. (vii) Print: View of underside of arch from nortwest. nd (viii) Print: The Free Bridge during floods. 1946. Copy of IGMT 1982.1541.
11 A Watching Brief at the Free Bridge, Jackfield, Shropshire
A WATCHING BRIEF AT THE FREE BRIDGE, JACKFIELD, SHROPSHIRE
BY H R HANNAFORD AND DR P A STAMPER
A Report for THE COUNTY SURVEYOR'S DEPARTMENT SHROPSHIRE COUNTY COUNCIL
12 APPENDIX I
INDEX OF SELECTED PHOTOGRAPHS
BLACK AND WHITE PRINTS FILM NO. FRAME NO. DESCRIPTION 93/31 Contact Sheet 23 Free Bridge from southeast 24 Pier from southeast 25 Bridge from east 26 Bridge from east 27 Bridge from southwest 28 Bridge from northwest 29 Bridge from northwest 30 Bridge from northeast 31 Bridge from northeast 32 Bridge from east, showing damage on 3rd column from left 33 Bridge from east, showing 1969 repairs to 3rd column from right 34 Bridge from south
93/54 Contact Sheet 17 South bank during demolition 18 Details of concrete and reinforcing 19 Details of concrete and reinforcing 20 Details of concrete and reinforcing 21 Details of concrete and reinforcing 22 Details of concrete and reinforcing 23 Details of concrete and reinforcing 24 Details of concrete and reinforcing 25 Details of concrete and reinforcing 26 South abutment 27 South abutment, details 28 South abutment, details 29 South abutment, decking 30 South abutment 31 South abutment 32 North bank 33 Reinforcing rods (NB turn buckles at bottom centre and bottom left 34 Reinforcing rods, details 35 North bank
93/56 21 Temporary bridge from southeast
93/57 Contact Sheet 16 Demolition debris, showing reinforcing 19 Demolition debris, showing reinforcing 24 Fishtail reinforcing rods 28 Detail of arch and reinforcing, south abutment INDEX OF SELECTED PHOTOGRAPHS
BLACK AND WHITE PRINTS FILM NO. FRAME NO. DESCRIPTION 93/58 Contact Sheet 1 Free Bridge before demolition, from southeast 2 Free Bridge before demolition, from northwest 4 Temporary bridge, from north 5 Free Bridge and temporary bridge, from northeast 6 Free Bridge during demolition, from northeast 7 Free Bridge during demolition, from northeast 8 Demolition rubble, detail, (NB turn buckles in top left- hand corner) 10 Free Bridge during demolition, from southeast 11 Free Bridge during demolition, from northwest 12 Free Bridge during demolition, from north 13 Detail of decking construction 14 Demolition crew 16 Free Bridge during demolition, from northeast 17 Free Bridge during demolition, from north 18 Free Bridge during demolition, from northeast, showing 1969 repairs to 3rd column
COLOUR SLIDES FRAME NO. DESCRIPTION 1 Free Bridge, before demolition, from southeast 2 Free Bridge, before demolition, from southeast 3 Free Bridge, before demolition, from southeast 4 Free Bridge, before demolition, from southeast 5 Free Bridge, before demolition, from northwest 6 Free Bridge, before demolition, from northwest 7 Free Bridge, before demolition, from southwest 8 Free Bridge, before demolition, from northeast 9 Free Bridge, during demolition, from northeast 10 Free Bridge, during demolition, from northeast 11 Free Bridge, during demolition, from southwest 12 Demolition rubble (NB turn buckles) 13 Demolition rubble on south bank 14 Free Bridge, during demolition, from southeast 15 Free Bridge, during demolition, from southeast 16 Spectators 17 Free Bridge, during demolition, from southeast 18 Demolition rubble, detail 19 Free Bridge, during demolition, from north 20 Free Bridge, during demolition, from northwest 21 Demolition rubble, detail showing corrosion 22 Demolition rubble, detail 23 Free Bridge, during demolition, southern pier