Tangmere

If you ain't gonna repeat it, why post this in the first place? Don't take notice of tittle-tattle anyway as so much turns out to be nonsense.

 

You'd

Exactly, well said. The gentleman sounds like a credit to his employers to me. Sharing thoughts, information, suspicions, hunches, call them what you will when it comes to learning lessons about safety can only be welcomed I would have thought ?

 

There's a lot of stuff that is "heard" but far from all of it is true. It's filtering the good from the bad that's the problem.

 

It does make you wonder though, where loco's have had replacement motion made because the originals have been lost ,then how simular is the modern metal spec? no modern steel is going to be an exact copy of what was made 60 odd years ago whilst it may be fine for preserved line use is it up to the stresses of main line use? after all an engineer may specify i need "x" material, based on what MT276 may say is needed, has the formula used by the steel works made the metal not quite spec?

 

Interesting question, but you'd like to think that if anything, modern metal technology could manufacture something even stronger and more robust than that used 60 odd years ago ?

 

You need to understand what you want and need before specifying the material, just making it harder/stronger may be a backwards step from a durability point of view. Suppose that what you need is a hard wearing outer surface yet a ductile interior to absorb shock loading, just using a harder material in that case may lead to brittle fracture.

 

Sorry, what conjecture? That the RAIB are doing metallurgical tests? Have you ever read any of their reports: they *always* do metallurgical tests when there's any kind of problem with any metal component. As conjectures go that's roughly on a line with conjecturing that bears s*** in the woods.

 

Agreed, and understood. I guess what I meant to say is you'd have thought new technology would have made it possible to produce an even more effective component

 

Martin Butler, have you ever read MT 276? No metal specs in it.
For metal specs of loco parts you need the British Transport Commission document Materials for Locomotives and Tenders. The NRM also have a few build schedules for certain Classes of loco, including the Bulleids. These give you the material specifications, as well.

 

The fortunate fact that the conductor rail caught Tangmere's rod and prevented derailment actually makes no difference to the assessment of the risk (likelihood and severity) of a similar incident in future. If a similar failure were ever to happen again, there probably wouldn't be a conductor rail there to save the day (50% chance on the 3rd rail lines, zero chance elsewhere). So, even though the consequences this time were not serious, the RAIB could still have said "No more steam on the main line until we've finished our investigation". The fact that they didn't say this implies that they are satisfied that the risk is acceptably low. (Zero risk is an ideal, rarely achievable.)

 

Excellent post !

 

They could have *recommended* that, looking at their website their powers are only to make recommendations. However the risk is demonstrably low due the the historical record of steam engines, even unrebuilt light Pacifics, only very rarely catapulting themselves off the lines. So that makes me **guess** that they'll be looking for more specific factors.

 

I stand corrected.

 

It's all about risk, but the risk can change very suddenly, and then you get all the "Why ?" questions. Imagine if a similar incident occurred in the future, God Forbid, and this time the outcome was less fortunate. How long would it be before the question, "why were steam engines continued to be allowed out on a 21st Century railway after it happened the first time ?" got asked, and then how many more times after that ?

 

I think you're correct. AFAIK it's other bodies who will act upon RAIB recommendations.

 

A little reality is required here. Steam locos are no more likely to be involved in a serious incident than modern traction. Yes the Tangmere incident could have been much more serious but then so could a hundred and one other incidents over the years involving much more modern motive power.