Pondering an idea that might've saved some lives..

[David Benton]

I wasn't thinking of having the pole strong enough to stop the car, just large diameter to spread the impact.
The problem with a break away structure would be the weight of the catenary structure itself coming down , as opposed to a liteweight traffic sign / light etc.

[rohr turbo]

Of course this guardrail, being on the inside of the curve, doesn't protect against overspeed derailments, but rather clotheslining ...

Yes, quite right.

To take Dave Benton's idea one step further: you could envision beefy catenary supports on only the *inside* of the curve and cantelevered out over the tracks! I don't think the gantry is that heavy. Then just put a ballast field on the outside of the curve!

This is a fun 'what if' exercise, but I truly think the best bang-for-buck is PTC or other electronic means of controlling speed. It should be so easy today with the power and low cost of GPS and mobile electronics.

[macnicol76]

Assuming the engine speed control system is "fly by wire" and the engine cab electronics have GPS position tracking for dispatch status and safety monitoring, then implementing location based speed limiting system should be relatively inexpensive and easy to retrofit.
 
Most automobile off-the-self GPS nav systems have max speed limits info built into them and provide a visual alert when one exceeds the max speed limit for a certain location and these retail for less than $250.  Connecting this alert electronically to the engine speed controls should be simple and inexpensive. Alternatively, networked track side transponders could trigger the governors as the train passed to change from one speed to the next.  Most any clever electronic tech could design and build a simple inexpensive system that could do that.  There are already networked systems that provide alerts and warnings to the engineers.

Google has already solved the problem with their driverless, auto-drive car systems.  These don't cost millions of dollars!
Of course these systems would have to undergo extensive safety testing before deployment.

Question: “How long does it take to get a 7 car passenger train up to 100mph from a full stop at a station?

Credentials: retired manager of avionics systems for advanced flight control systems for current generation Air Force fighter-bomber systems.

[justalurker66]

To take Dave Benton's idea one step further: you could envision beefy catenary supports on only the *inside* of the curve and cantelevered out over the tracks! I don't think the gantry is that heavy. Then just put a ballast field on the outside of the curve!

I had the same vision ... but for four tracks the weight could be considerable. The tension of the wires pulling toward the inside of the curve would add to the physics problem. The outside of the cantilever would likely need to be anchored to keep the cantilever level.

An interesting concept ... how to make rails safer when trains crash ... but I'll join in the agreement that the best solution is don't crash trains.

[hi55us]

When I first read this thread title I thought you were going to suggest moving the Business Class car to the rear of the train... which I think the data will show is more likely to be safe in an accident...

The current practice of having the rear car or two closed during off-peak periods (I believe the last car was closed on #188) pushes more people towards the front of the train and had the first car been empty on this train, the accident would probably been much less fatal.

[macnicol76]

If we are limiting the discussion to derailments on curves due to excessive speed, then why not just bank the curves like in high speed race tracks? If you look at European tracks they are banked and the cars are equipped with leveling hydraulics that tilt the cars to counteract the centrifugal forces on passengers on curves.

Also an automatically actuated counterbalance weight that would extend out from the inside curve side of a car during a curve as the car tilts toward the outside of the curve. Would be installed on both sides of a car. Not sure how much weight would be required to counterbalance a car, may be impractical.

Also have a crash buffer car before the passenger cars that is compressed and absorbs the crash. Service cars should be toward the front and passengers cars to the rear.

Was there any benefit for passengers facing backward during a crash? Would seat belts have helped?

Would enclosed overhead storage compartments help protect from flying objects?

[etna9726b]

Re: Banking. Superelevation or Cant is the term for banking in railroad tracks. And they already are. When considering how much cant is required, one has to take into consideration both the speed and weight of the trains that traverse the curve. Too little cant (cant deficiency), and centrifugal force pushes (pulls?) trains off the outside rail. Too much cant and the train slides downward, rubbing or derailing on the inside rail. Safety is the big goal, reducing rail wear is the more common goal.

If cant, speed, and weight are perfectly matched, you'd feel only a downward G force in your seat, no lateral forces. Envision that amusement park ride with the chairs hanging from long chains. The faster you went, the chair swung outward (a change in cant). You always just felt heavy in the seat.

Remember challenging your high school geometry teacher when we'd use this stuff? Yep.

[BR&P]

When I first read this thread title I thought you were going to suggest moving the Business Class car to the rear of the train... which I think the data will show is more likely to be safe in an accident...

The current practice of having the rear car or two closed during off-peak periods (I believe the last car was closed on #188) pushes more people towards the front of the train and had the first car been empty on this train, the accident would probably been much less fatal.

The problem is it's impossible to predict what TYPE of accident will occur next. You mention closing off the rear car or two. If, instead of an overspeed derailment, this incident had involved #188 being rear-ended by a following train for some reason, those empty cars would have saved lives for sure.