From: nick+usenet@nicksandru.com
On 02/16/2015 10:25 AM, Adam H. Kerman wrote:
> bob wrote:
>> On 2015-02-13 20:23:01 +0000, Marc Van Dyck said:
>>> rcp27g@gmail.com explained on 13-02-15 :
>
>>>> or putting in positive singalling control on others (ie where the
>>>> crossing is protected by railway signals that aren't cleared for the
>>>> train until the barriers are down and the crossing positively checked
>>>> to be clear).
>
>>> This is perfectly feasable but requires to order the gates to go down
>>> at a distance that is longer than the braking distance of the train.
>>> This means there will be a long delay between the gate going down and
>>> the train actually passing the grade crossing.
>
>> Indeed, this is the case. It is less convenient but allows for
>> positive safety.
>
>>> As it has been mentioned,
>>> motorists are unpatient creatures; if the delay is too long, people
>>> think the gates are faulty and start turning around them. You might end
>>> up this way with a grade crossing that is inherently less safe, because
>>> of human nature...
>
>> Solved by making the barriers block the whole road. As the crossing is
>> positively checked to ensure the barriers are down and the crossing is
>> clear before clearing the signals for the trains, the issue of cars
>> being trapped within the crossing is avoided.
>
> Clearing level crossings several minutes before the train arrives mitigates
> against non-existant risk, and it's quite labor intensive. How is the
> cost of delay justified? How is the personnel cost justified?
>
> No lives have been saved except during the 5 or 10 seconds before the
> train arrives.
>
>> The usual design in the UK, for example, is for the road to be blocked
>> by four barriers: each covering half the roadway on each side of the
>> railway. The warning lights/klaxon start first, then the "entry" side
>> barriers come down, then the "exit" side barriers come down, then the
>> klaxon stops (it gets irritating, and once the barriers are down, is
>> redundant). Then the crossing is checked to be clear, either by a
>> person in a local signal box or by CCTV cameras, and if it is clear,
>> the signals are cleared for the train or trains passing. It is safe,
>> but means waits at the crossing can be a couple of minutes before the
>> train actually arrives. The crossing sequence is initiated by the
>> signalman, who can keep the crossing down if there are multiple trains.
>> They can be annoying, but they are safe.
>
> I've heard of crossings getting closed five minutes ahead of arrival
> of the train.
>
>> Not all crossings in the UK are of this sort, there are also "automatic
>> half-barrier" crossings that do not block the whole road and are
>> triggered automatically by the train approaching, without positive
>> safety, but designed for the minimum road-closed time, so the barriers
>> come down about 20s before the train arrives. Such a crossing was
>> involved in the Ufton Nervet crash, and they are only used on quiet
>> roads with little traffic, and on railway lines with lower speeds.
>
> That's common in the US.
>
The Russians have found a much more efficient solution to keep the
idiots off the tracks:
http://erkkit.smugmug.com/Motorcycles/Return/i-L8HhJ9/0/L/image336-L.jpg
The steel plates in the roadway are raised when the gates come down.
Vehicles caught in the crossing can move away from the crossing as the
plates are pushed down by the vehicle's weight. But if you want to beat
the train then you will need a pair of new tires...
Of course, if such a solution would be introduced in the US, railroads
would be forced out of business as they would have to defend themselves
from being sued by idiots whose care got damaged. An there is also the
sovereign citizen/libertarian crowd who would never relinquish their
$DEITY given right to be killed by a train.
--
Nick Sandru
Somerville, NJ
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