I am writing urgently to you concerning Northmoor Weir, Oxfordshire, and the proposal by the Environment Agency to spend about £3 million, I believe unnecessarily, to
replace the present weir. This is at a time when many households in the region live with a risk of flooding and cannot get adequate funding. If the project goes ahead, the work could start in a few weeks.
The justification to replace the weir is based on the results of load tests to
remove paddles from the weir. The recorded loads exceeded the levels recommended by the Health and Safety Executive. I believe that excessive loads were measured because the tests did not replicate the normal actions of a lock keeper. Also, the more representative steady state loads were not recorded.
Only single jerk/impulse loads were recorded which do not represent the
lock keeper’s normal lifting loads.
Consequently, I believe the test results are invalid. However, these impulse loads are now being used to justify replacing the manually operated weir because they exceed the maximum values recommended in the HSE Manual Handling Guidance (Ref 1).
I believe the testing should be repeated by a lock keeper removing paddles in exactly the same way as the lock keeper normally does. The test procedure should be
modified to record all the loads, including the steady state loads.
I am concerned about these tests because of my experience at work and because I am a Vale of White Horse District Councillor for Appleton and Cumnor, which includes Northmoor weir. I am a Chartered Mechanical Engineer and I have been involved in research, testing and investigation throughout my career. I worked at the Health and Safety Executive as a Principal Health and Safety Inspector for 9 years and Technical Author of HSE publication ‘Developing and Maintaining Staff Competence’ (Ref 2).
Testing at Northmoor Weir
I have examined the video that EA made during the testing (Ref 3) with retired Lock Keeper and Team Leader Upper Thames Navigation Officer, Chris Mullineux, and read the report subsequently provided by Human Applications Ltd (Ref 4). We were
shocked to see how the tests had been carried out and the results recorded. As a
result, I believe the test results are invalid and the testing should be repeated for the following reasons.
- The method used does not replicate what the lock keeper normally does to remove a paddle.
- A lock keeper, holding the force gauge on the end of a rope tied around the
paddle, meant that he could not handle the paddle normally.
- The straight pull to remove the paddle required much more force than moving the top of the paddle from side-to-side (levering it out using the ‘Northmoor shimmy’ method: Ref 3, video timed at 3.02 mins and 11:16 mins) until the paddle can
be removed easily.
- The flow of the water under the paddle was not used to help raise the paddle. The normal lock keepers use the water flow to raise the paddle, as shown in the BBC clip on YouTube (Ref 5).
- The simple type of force gauge used only recorded the maximum force and not the steady state force. This ‘jerk’ force recorded is not representative of the steady state loads and forces that the Manual Handling Guidance refers to.
- In the video recording made at Northmoor the Ergonomist says “Some problems with the tests; makes it more difficult and harder to remove them.” These comments are not recorded in the report on the tests (Ref 4).
- The paddles are not actually heavy, weighing between 11 kg and 15 kg depending on the length of the handle. The lock keeper does not have to lift the paddle onto the walkway as he can use the edge of the walkway as a fulcrum to lever the paddle onto the walkway. He can drag the paddle along the walkway or ‘walk’ it along by moving the handle slightly from side to side. So little actual lifting is required. I can lift a paddle with one hand.
- The force of 603 Newtons (61.5 kg load) was recorded at Northmoor weir. This load is excessive. It is over four times the normal weight of the heaviest paddle. For comparison, it is over three times the weight of the heaviest airline case.
The maximum recorded load of 61.5 kg was more than the maximum load of 25 kg recommended in the Manual Handling Guidance. But the 61.5 kg is an impulse load, whereas the 25 kg recommended maximum refers to a steady state load. Therefore
the ergonomist’s recommendation that the weir should be redesigned to reduce the forces and the risk of musculoskeletal injury for the lock keepers is, in my view, invalid.
The evidence is not sufficiently reliable to justify spending about £3 million to replace the weir based on the requirements of the Manual Handling Guidance.
The Health and Safety at Work etc Act 1974 states that risks should be ‘as low as reasonably practicable’ – the ALARP principle. Also, the Manual Handling Guidance (Ref 1) provides practical guidance on avoiding, assessing and reducing risks.
However, there are no records of reported accidents and incidents from the operation of paddle and rymer weirs such as at Northmoor weir. Therefore the risk of an accident is already known to be very low.
Testimonials from Former Lock Keepers
The attached document from Chris Mullineux (Ref 6), lock keeper and Team Leader, Upper Thames Navigation 2003 – 2009, describes the operation of a paddle and rymer weir and the safety training required for lock keepers. Chris Mullineux has also written a note on the Northmoor lock and weir and its heritage (Ref 7). There is a the
testimonial from Colin Buddin (Ref
who was the lock keeper at Northmoor for 32 years and was the Union Health and Safety Rep for about 8 years. He is over
70 years old and still in good health.
They both testify that the loads to operate the weir are not excessive. Also, they say that when the river level rises from a lot of rainfall lifting the paddles actually becomes easier. In addition, if the Thames floods, it occurs one or two days after the weir has been fully opened. So there would be no benefit from having a fast electrically operated weir. Indeed, the reports also confirm that opening a weir too quickly could be dangerous. In addition, Nicola Blackwood, MP, recently confirmed in Westminster Hall
that ‘the EA specifically confirmed to me in writing, and at the meeting of December 2011, that the project would not reduce flood risk in any way’ (Ref 9).
Recommendations for Repeat Testing
It is for these reasons that I believe the testing should be repeated, and I would like to make the following suggestions.
- A sleeve is fitted over a paddle handle so the lock keeper can grip the paddle in
the normal way.
- The load gauge is attached between the sleeve and the paddle to measure the forces accurately.
- The load gauge must be able to provide a continuous output of the force applied to the paddle.
- A data recorder is used to continuously record the lifting forces to remove the paddle.
- The
normal lock keeper, or one of the regular relief lock keepers at Northmoor, removes the paddle in exactly the same way as he normally does.
- The testing is managed by a Mechanical Engineer who is experienced and competent to do the tests and record the results. I would be happy to assist.
- An ergonomist is asked to interpret the test results and advise on any human factors involved in this work.
- The tests should be witnessed by an experienced lock keeper, someone with experience of carrying out similar tests (again, I would be happy to assist) and a representative appointed by Appleton with Eaton Parish Council.
The measured forces should then be compared with the guideline load of 25 kg for lifting and lowering in the Manual Handling Guidance (Ref 1). If the measured loads exceed the recommended maximum loads a detailed risk assessment should be carried out, as shown in Appendix 4 of the guidance (Ref 1). Then, if any remedial actions require funding, a full cost-benefit analysis should be carried out on all the alternative remedial actions.
A full replacement of the weir, at such huge cost, would seem unnecessary given the testimonials of the lock keepers and solutions, such as the paddles and rymers made from an alternative composite material, should tried and tested first. This option would have the advantage of preserving the heritage of these paddle and rymer river navigation structures – unique to the River Thames.
I am writing to you at this time because the BBC archive footage makes it clear that a lock keeper can readily remove a paddle from the weir without undue exertion. A local engineer who has studied the DVD with me to assess the problem has volunteered to make a sleeve to fit over a paddle handle and to assist if needed.
If the replacement of the weir cannot be justified on transparent economic and ergonomic grounds the project should be abandoned, and an independent
investigation should be carried out to determine how the Agency arrived at this situation.
Yours sincerely
D S Hoddinott
Dr D S Hoddinott, PhD, CEng, MIMechE
District
Councillor for Appleton and Cumnor
Vale of White Horse District Council
References
1. Manual
Handling – Manual Handling Operations Regulations
1992: Guidance on Regulations L23.
Health and Safety Executive, Third edition 2004, ISBN 978 0 7176 2823 0
2. Developing
and Maintaining Staff Competence, HSG 197 HSE Books 2002, ISBN 0 7176 1732 7
3. EA
Paddle and Rymer Ergonomic Assessment, 9 April 2010, video made by Environment
Agency
4. Ergonomics
Report of Pull Out Forces for Streatley, Northmoor and Rushey Weirs, Lisa
Rogan, Human Applications Ltd, April 2010
5. BBC archive footage, Local (Oxford) News, 2 March 2012 and YouTube clip – http://www.youtube.com/watch?v=7Xbhh0-awFA
6. Paddle
and Rhymer Weir Operation, Chris Mullineux, Retired Lock Keeper and Team Leader
Upper Thames Navigation 2003 – 2009, February 2012, ATTACHED
7. Northmoor Lock and Weir, a note by
Chris Mullineux, Retired Lock
Keeper and Team Leader Upper Thames Navigation 2003 – 2009, February 2012, ATTACHED
8. Northmoor
Paddle and Rymer Weir: Testimonial
of Colin Buddin, retired Northmoor Lock Keeper 1971
– 2003, February 2012, ATTACHED
9. Private
Members Debate, Westminster Hall, Nicola Blackwood, MP for Oxford West and
Abingdon, 27 February 2012