Is reversing points the best way to prevent another Grayrigg?
With reference to the letter “Reverse approach could cut Grayrigg points risk (Letters last week), I would draw Lindsay McGibbon’s attention to the fact that there was an accident at Grayrigg in 1947 when the crossover had trailing points of the type he advocates.
The track in this area is on a steep falling gradient heading south. To reverse through the crossover it was necessary to have a locomotive waiting below the stopping point to help trains back up the hill.
On 18 May 1947, during single line working for track laying, an up express didn’t stop in time and hit the waiting pusher, causing a derailment on the nearby Docker viaduct with serious injuries but no fatalities.
Possibly the facing points crossover which caused the 2007 accident was then installed to avoid the hazards associated with backing a heavy express train uphill.
My solution would be a trailing points crossover as advocated by McGibbon but located a few kilometres to the north in the Lune gorge on the level section at Dillicar where the water troughs used to be.
- Uter Potter (F), Windermere, firstname.lastname@example.org
Lindsay McGibbon’s letter last week about the crossing that caused the Grayrigg rail crash set me researching, and I find that Network Rail has taken the hint and done away with it altogether; but that still leaves thousands of “facing points” all over the country which really are necessary.
In the 1970s London Underground went over to a radically different system for its points, so that the movable pieces of rail were locked directly to the stock rails, instead of relying on the actuation mechanism with its several connections and spreader bars.
It was called a chair-lock system, and derived from a French innovation brought on by the backlog of maintenance on the Continent during and after the Second World War.
Notably though, in its report on the Grayrigg accident, the Rail Accident Investigation Branch didn’t recommend a change of this kind to Network Rail, but instead went for a raft of piecemeal improvements to the traditional system and the inspection regime.
Who is to say that isn’t the right approach?
- Christopher May, (M) 6, Leewood Road, Weston-super-Mare BS23
Lindsay McGibbon’s solution (Letters last week) to the cause of the disaster at Grayrigg is a scarcely novel one.
From the early days of railways, the risk of derailment at facing points soon came to be recognised and the principle was established that running lines should incorporate only trailing points.
It is only in recent years that railway administrations have deemed that the risk inherent in the installation of facing points was worth taking in return for operational convenience.
When will wisdom be restored?
- Peter O’Neill (M), The Old Village Hall, Cocking, West Sussex, . 0HN
Application plus information
“BIM is the word” (NCE last week) provides plenty of evidence to support the vision that BIM will prove to be a major agent for change. It does not, however, provide criteria for recognising what BIM is.
This is not surprising. Many writers have identified two complementary views of BIM, one being that it is software and the other that it is a process.
The latter, more strategic view, recognises that ultimately it is the information that is important. It is interoperability and the integration of that information across processes (at any stage and down the building lifecycle) that will drive change.
The more immediate future is conditioned by the functionality of the current BIM authoring software and by the limitations on its ability to interoperate (as evidenced by the popularity of Navisworks).
Returning to the question of what BIM authoring software is, the essential feature of such software is that the model it maintains is information not graphically based.
Thus, while traditional CAD systems manipulate a graphical representation of the building, BIM software generates - in real time from the underlying information model - the multiple representation(s) with which the user interacts while manipulating the underlying model.
- Alastair Watson (M), Institute for Resilient Infrastructure, School of Civil Engineering, The University of Leeds, A.S.Watson@leeds.ac.uk
The government is contemplating a detailed study of air traffic requirements in the UK and particularly in the South East. It is to exclude Heathrow, currently by far our largest international hub.
The third London Airport Inquiry was conducted 40 years ago and the results of this one will not be serviceable on the ground before 2030 or so, 70 years or more after the need was recognised!
The congestion at Heathrow is undoubtedly becoming greater and the government’s decision not to permit another runway was premature and quite possibly foolish.
However, Heathrow has all the supporting infrastructure of housing for its workforce, industry and commerce located near the airport by choice because a hub airport meets their needs and a transport network linking well with London, which may need updating in the longer term but which meets current requirements.
An in depth study may show that Heathrow is inappropriate for the future but to prejudge that and omit it from any in-depth study is crass. It seems like conducting a study of the social needs of the population, confining it to data on people who have lost a limb. The outcome will lack similar balance.
Surely it is time for the government to swallow its pride and make Heathrow part of its study.
- Stefan Tietz (F), email@example.com
Practising what is preached
We have read with interest the comments on equality in construction.
As the first UK SME to achieve the UKRC SET Fair Standard for gender equality back in 2010, as a company we had to reflect on why we more equally represented society than most.
Bluntly, recruiting the best from the entire working population and not just half of it makes commercial and technical sense for us.
However, we need to see those female graduates in order to make that choice.
Just as nursing is no longer seen as an all-female career we have to change the perceptions of civil engineering of those that influence the young.
It’s not a question of the Christmas “dolly or digger” but stopping the older voices saying, “girls don’t do that job”.
Role models are essential and we were able to show that at the UKRC 2010 “Women mean Business” conference in a video of site works where project director, design and site engineers, contractor’s agent and dumper driver were all female.
This is powerful stuff in the minds of the young. The rest will come from awakened interest and commercial choice.
- Nick Langdon (F) Jo Strange (M), Card Geotechnics, Aldershot.
High speed all the way?
As the government defers its decision on approving plans for HS2 while it considers a very costly tunnel under a key section of the route to limit the visual impact of the line, it is worth noting that objectors have made particular criticism of the scale of the earthworks and therefore of the height of embankments and the width of the right-of-way needed for deep cuttings.
There appears to be an implicit presumption that the maximum line speed should be maintained along the whole route, but surely a fairly modest reduction in the areas of particular scenic beauty would lead to a reduction in the radius of the vertical curves (a critical factor) with both a substantial saving in construction cost and a major improvement to amenity.
Have the promoters given serious consideration to this aspect?
- Peter O’Neill (M), The Old Village Hall, Cocking, West Sussex, GU29 0HN
Am I alone in experiencing a feeling of unreality about the Thames Tunnel mega-sewer project. Surely its time for a reality check − making the Thames a bit cleaner versus a flat lining recession.
Apart from the activity in actually building it, the sewer project will contribute absolutely nothing to the British economy.
Alistair Biggart (NCE 24 November) compares it to the 1930s Hoover Dam as a job creation project, but the Hoover Dam did generate electricity and provide flood control.
If we really have £4.1bn to spend on a Hoover Dam in these tough times, it shouldn’t be spent on yet another London mega project, contributing nothing lasting to the economy.
The real priorities are roads, railways, high speed broadband, and, renewable energy generation.
- Jim Walker (M), Keighley, firstname.lastname@example.org
The SS Montgomery has remained a threat to the south of England for too long.
With LNG tanks at the Isle of Grain, storage at Canvey and the Thames Barrier at Woolwich, the south east is living under a sword of Damocles.
I am not an expert on explosives but there have been many advances in analysis, techniques and equipment. I believe this problem can be removed at not excessive cost.
Perimeters of cofferdams can be installed around the vessel including measures to absorb and deflect any blast. Piles can be installed using the most appropriate frequency equipment at a rate to prevent disturbance.
The vessel is in shallow water. Water pumped out of the outer perimeter can prevent tidal wave formation. The innermost perimeter will remain full of water to maintain the vessel in its undisturbed state.
Remotely operated equipment can then be used to gradually dismantle the ship using high pressure water cutting. The explosive could then be removed in liquid form or made inert through the injection of chemicals.
The development of a major city should not be held ransom by approximately 1,400t of explosives. The Maritime & Coastguard Agency regularly sends in divers and surveyors.
If we can get that close surely we can come up with something better.
- Jeremy Carter (M), Henfield Road, London, SW19 3HU
Letters to the editor
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