Brunel's Other Bridge Bristol Swivel Bridge 2016

Brunel Swivel Bridge Project 2016

Investigating what lies under the patches

CONTRACT WORK undertaken up to March 2016:

Trial dry-ice and abrasive grit blast-cleaning.
Trial cutting out and welding in two patch-repair plates.
Trial removal of rivets and hot-setting new rivets to match.
CCTV drain survey.
Removal of one hydraulic ram, dismantling, inspection and refitting in its pit.
KGAL design for method of centring and driving round the deck-structure, provision of costings.
Geocon Ltd ground investigations.
Hole cut in top-tube end-plates to allow internal investigations.
Removal of all 20th century patch-plates, measurement of local plate-thickness.
Preparation of outline schedule of work and costings.

Preparation and Basic Conservation

Removing patch-repair plates to allow us to clean and inspect the inside of enclosed sections, and work out cost of repairing properly.
Detailed investigation of the foundations

It is a concern that any hours we spend can not be counted as match funding until lottery funding has been granted. Work is limited since we are not allowed to start restoration work til we get our funding, so any work has to be investigative.

Volunteers still have useful work to do including clearing rust from inside the holed parts, inspecting interiors, measuring plate-thickness, fitting the timber stops, gardening, refitting the ram that was removed, clearing silt from pits, painting, etc.

Likely dates of work for 2016 (We will working 'one day per month' normally on SATURDAYS rather than a whole weekend):

SUNDAY April 17th (16th is the SW Regional IA Conference, hosted by GSIA)
May 28th
June 18th (19th is Father's Day)
July 16th
SUNDAY August 21st
Sept 10-11th so as to coincide with Doors Open Day - open on Sunday. WARNING traffic will be horrendous on Saturday due to the Tour of Britain
October 15th Cancelled due to other commitments, and time needed to prepare for application for lottery funding. Contact Maggie if you want to help

Sounds like fun? No experience needed, all equipment provided, and you'll get really involved in helping to save Brunel's Other Bridge. We need your help.

Contact Maggie Shapland (Maggie.shapland@gmail.com) if you wish to help. We need to have an idea of numbers.

Overall Details of work

Funding

As you know, the Bridge is listed Grade 2* and is on Historic England (formerly English Heritage) Buildings at Risk Register. Whilst their funding is severely restricted, HE have been supportive in providing modest grants to carry out trials and erect a temporary roof, which were completed by Bristol City and Avon Industrial Buildings Trust with volunteer help last year.

EH/HE were impressed with the Mann Williams (MW) report that resulted from the grant-funded work that we managed on behalf of the council in 2015 and suggested that we discuss an application for further investigative work on critical areas identified in the report as part of this year's Heritage at Risk programme. They also suggested that we might request further assistance in other areas via their consultancy budget and service.

13 December: We have now reached the stage where we need to employ more professional expertise to make further progress. To this end , Historic England (HE) have offered a further grant to assist the replacement of the worn components of the turning mechanism of the bridge prior to the first swing since 1966.
We are currently finalizing our thoughts on:
- How to restore the four wheel's circumferences and stub-axle journals where corroded,
- How to re-face the severely corroded underside of the track, or alternatively to renew it.
- How to hold the rotating assembly central.
13 December: Coop Community Fund We have some good news - the Coop are extending the funding period for the Local Community Fund to 8 April 2017. This means that members can choose our cause and support you for an extra 3 weeks. We will still get the money by the end of April 2017. Money raised so far: Our share of funding is currently £942.55 (the most voted for in the Clifton community).
21 September: Coop Community Fund
The Brunel Swivel Bridge has been selected to receive funding from the Co-op Local Community Fund. It means that we will get a contribution towards restoring the bridge. But we need your help. The more support we get, the more funding we could receive. So if you're a Co-op Member log in to your Co-op Membership account and choose us. If you're not a member, please join and support us! https://causes.coop.co.uk/promotional-guide for more details
Every time members choose Co-op branded products and services and use their Co-op Membership card (subject to Membership T&Cs) 1% of what they spend will go to their chosen cause. You can now see the cause profile on the Coop membership website. https://membership.coop.co.uk/causes/1505
April 2016: The estimated total costs of restoring the bridge and putting it back into commission is £695,000 and would take 9 months.
Jan 2016: John Richfield of the 'Cycle' team at BCCouncil has now raised an order (payable to AIBT) for £14999 (he has to come in below £15k. owing to their financial guidelines) to support our HLF bid.
Dec 2015: The EH conservation grant panel approved the offer of a grant towards further project development work for the Swing Bridge over North Entrance lock to progress immediately. The grant offer is for £12000 (plus an additional sum to cover VAT on top of this) for investigative work on two critical areas identified in the Mann Williams report that will be necessary to inform contractors if (but hopefully when) we move on to the HLF-funded stage.
The grant aims at covering the costs related to investigations of the foundations and the plate thickness measurement.
- Removal of welded-on patch-plates by grinding off welds, and measurement of the remaining thickness of existing plates around holed areas. Contractor: Dorothea Restorations (Wallis Conservation Ltd) of Bristol. Contact Geoff Wallis jandgwallis@gmail.com.
  The plate-thickness survey of concealed areas is to establish as accurately as is possible the amount of iron that needs to be replaced.
- Investigation of the ground around the Swivel Bridge, including a cable percussion borehole, one day's trial pitting at three or four locations up to 3.5m mbgl, with insitu geotechnical sampling, all supervised by an engineering geologist, and an archaeologist. Contractor: Geocon Site Investigations Ltd of Almondsbury. Contact Bob Watkins bobwatkins@blueyonder.co.uk
  The detailed investigation is of the foundations on which the bridge will turn reliably and effectively. This an area of concern as the bridge has not operated since the mid-1960s and survey suggests that there has been some movement in this respect.
Match funding of £3000 is required in connection with this grant. The work must be completed and invoiced by early March.
Dec 2015: AIBT has additionally been offered £4000 for consultancy to advise on the replacement of the hydraulic system which was identified as beyond repair in the MW report.
Feasibility study for the design of an hydraulic system to rotate the Bridge after its restoration, powered by the local 3-phase electrical supply. Contractor: Kgal. Contact Geoff Wallis jandgwallis@gmail.com.
We talked to contractors and HE engineers with a view to obtaining advice and costings for equipment to enable the bridge to turn frequently and effectively. We have also liaised with the Harbourmaster and the Docks Engineers concerning possible future bridge operational requirements. We have to pay VAT on this consultancy from the £4k. but there is no match-funding requirement and we should be able to achieve our objectives within this budget.
Depending on funding other additional minor works may also take place. Work started in January with site work being completed by 19th Feb to comply with HE's budgetary constraints. The contracts will be let by the Avon Industrial Buildings Trust and supervised by their Technical team, comprising Alf Perry, Bob Watkins and Geoff Wallis.
We are delighted to see work by the professionals starting on site and want to thank Bristol City Council, English Heritage, the local amenity societies, our faithful hard-working volunteers, and huge number of supporters for getting the Project this far.
The big challenge lays ahead in securing major funding, but by March 2016 we hope to have a well-specified and costed scheme for repair which will form a sound basis for fund-raising.

You can make a donation using a charity website. The main donation link now uses the Wonderful fundraising website:
https://www.wonderful.org/charity/avonindustrialbuildingstrust

We have created a project on http://www.neighbourly.com to also help us fund raise for our HLF bid

or you can send a cheque payable to
Avon Industrial Buildings Trust to:
The Treasurer, Thatched Wells, Duckhole, Thornbury, BS35 1LD.

Leaflet giving information, asking for support and how to make a donation

Progress in 2016

Look at the reports page to see the summaries of the results of inspections of the bridge. Updated 11 January 2016

Photos of Progress in 2016

September 2016

Doors Open Day Photos of Progress in September 2016

August 2016

Tasks

Continue constructing the second timber stop
Clean out the south hydraulic ram-pit
Clean the bronzes removed from one of the turntable wheels
If anyone has the skills, make a new pattern of the bronzes so that we can have them re-cast.
Carry out general gardening and tidying up
see Ian with his wonderful 9' model of the bridge up at the Model Engineers Show in Thornbury

Photos of Progress in August 2016

July 2016

Tasks

Continue constructing the second timber stop
Cleaning and painting corroded areas of wrought iron plate.
Cleaning and repairs in the hydraulic ram-pits
Cleaning the bronzes removed from one of the turntable wheels, measuring up and preparing a drawing of them.
If anyone has the skills, making a new pattern of the bronzes so that we can have them re-cast.
General gardening and tidying up.

Photos of Progress in July 2016

June 2016

Tasks

Fit a metallic cover onto the first timber stop, paint black.
Start renewing the second timber stop. Wood-working tools needed.
General gardening and sweeping up.
Clear out and sweep the timber shed. (We can set up brewing facilities here if we wish.
Talking to visitors.
Measuring the centrality of the cast iron bed and wheels in relation to the pintle.
Removing the caps from the south west wheel bearings, lifting the wheels, measuring the cast iron pan below and removing the top bronzes.

Photos of Progress in June 2016

May 2016

Tasks

prime task is to remove, fit and re-erect the timber stop we half finished last time. For this we need to build a scaffolding trestle and pull out the wedged timbers with a chain hoist
Clear rust from inside holes where plates have been removed.
General tidying up, removing weeds, moss, etc.
Cleaning and painting vulnerable rusted platework.

Photos of Progress in May 2016

April 2016

First volunteer day of the year spent tidying up, continuing with renewal of timber stops, measuring the turntable rotor wheels and checking tie-rods and cast iron end fittings.

Filling the voids in the excavations and laying tarmac.
Continuing with renewal of timber stops.
Clear rust from inside holes where plates have been removed.
General tidying up, removing weeds, moss, etc.
Cleaning and painting vulnerable rusted platework.
measuring the turntable rotor wheels
checking tie-rods and cast iron end fittings

We had a brilliant day as far as weather was concerned, and a pretty good day as far as further investigation and work was concerned. Amongst other things, we were able to get good measurements on the rotor wheels for the turntable and additionally we were able to peer into the void of the top flange on the southern edge beam at a couple of locations.

turntable rotor wheels
The diameter of the wheels was calculated from the dimension around the perimeter, measured a couple of times with a thin flexible wire wrapped around the circumference of the rim. As you will see, the wheel in the NW quadrant was significantly smaller than the other three wheels and the flange on this wheel was also very damaged – in places non-existent. Since the perimeter dimensions were taken in two places (near the inner and outer edges of the rim – not on the flange), this showed that the rim is quite level. The slight exception was on the wheel in the SW quadrant where the perimeter near the flange was slightly less than the perimeter near the edge, albeit the difference in perimeter was only 10mm.

The original Brunel drawing, dated 1849, showed wheels at 2’-6” diameter, but there is correspondence from Brereton, the Resident Engineer, to say that this was to be altered to 2’-3” (it is thought). The latter is quite close to the largest diameter deduced from yesterday’s measurements (681mm = 26.81”) and, assuming that the wheels were all cast from the same mould, then this suggests little wear on three of the wheels and more significant wear on the wheel in the NW quadrant – which was quite damaged in any case.

Hopefully, this will help us taking forward options for repair of the wheels and the turntable beam.

Assuming that the wheels were originally cast to 27 inches diameter, and that we still have the original wheels, the minimum loss of diameter is 1/8 inch and the maximum well over 1 inch (on the NW wheel). Clearly scuffing has caused wear over a long period probably due to one or more of the following:

misalignment of track or wheels,
the fact that the track and wheel circumferences are not angled to the theoretically ideal 9 degrees.
the bridge deck not being held central by the pintle & its bearing.

If the proposed gear/pin-rack drive is to stand any chance of working we shall need to get everything well aligned so as to reduce the torque required to rotate the structure. Quite a challenge!

tie-rods
It is reassuring to see the relatively good condition of the tie-rods and cast iron end fittings, and if they are all like this we probably will be able to extract one or more wedge and re-tension the tie-rod on the south side. It appears from these that at least the end tie is in fair condition as is the internal surface of the iron – as far as we can see.

Photos of Progress in April 2016

February 2016

Work by the professionals continued

Excavations beside the bridge have revealed the nature of the ground, and a boring has confirmed the level of bedrock below so that the strength of foundations can be assessed.
Cheshire Drilling ascertained that bedrock was 11m below clay
Three investigative trial pits showed that the timber foundations did not extend beyond the bridge. Several pennant flagstones were retrieved
The steel patch-plates welded over fifty holes in original Brunel wrought iron structure have been removed and original plate-thicknesses measured to allow more accurate estimation of the cost of repairs. Small samples of original plate will be tested to further inform the design process.
Holes have been cut in the plates of the 'free' end of the Bridge to enable us to inspect the interiors of Brunel's riveted top-tubes, and their hidden tie-rods using an endoscope.
Specialist consultants have designed a 'preferred' method of restraining the Bridge concentrically around its central bearing, and driving it round with minimal visual intrusion, not easy when everything is susceptible to flooding at spring tides!

Photos of Progress in February 2016

January 2016

Work by the professionals starting

Plate thickness-measurement works were tendered and three competitive prices were received. As they submitted the lowest tender, we checked with Wallis Conservation Ltd (Dorothea) that they have allowed for the necessary H and S documentation, and temporary works, and that they can complete the investigative work by mid February, all of which they confirm. Dorothea have now started on site and have made good progress removing plates.
Historic England received two credible tenders for the hydraulic study. The lower one was from Ken Grubb Associates who designed the existing hydraulic systems that power the entrance lock gates and paddles. HE have instructed KGAL, and confirm that the cost does not come out of our £14K grant for the current investigative work. Bob hopes to get the ground excavations contractor started on site on monday 1st February.