A well-known safety problem with trains is their stopping distance often well exceeds how far the conductor can see. By the time they know there's a car stopped on the tracks, it's too late to stop. To solve this problem, have a small vehicle lead in front of the train, watching for obstacles, just ahead of the train's stopping distance. If something is in the way, the vehicle can stop safely and warn the conductor, allowing them to bring the train to a halt before it's too late.

Of course this won't prevent cases where something finds its way on the tracks after the sentinel has gone by, but you can't win 'em all; it should still help in the majority of cases.

The sentinel itself could simply be a modified smart car, keeping as small as possible to minimize fuel consumption and its own stopping distance.
-- Bukkakinator, Jul 10 2008

Almost baked http://www.patentst...6345233/claims.html
patent for GPS and train proximity detector [Cedar Park, Jul 10 2008]

What if the sentinel malfunctions and stops?
-- 4whom, Jul 10 2008


I wanna see a little (motorized) cart with a mannikin on top waving its arms in the air and going "AHhhhhhhhhhhhh..." as it's being chased across the country by a train... but maybe that's just me.
-- FlyingToaster, Jul 10 2008


I see one problem here. The safety gates at crossings would be required to remain closed longer than otherwise, to allow for the sentinel and the gap between it and the train. This may further exasperate motorists waiting to cross, increasing the probability of them trying to drive around the gates. Especially when they see the sentinel pass, and assume that was the [only] vehicle that was on the tracks.
-- CaptainCrunch, Jul 10 2008


//What if the sentinel malfunctions and stops?// The train either stops, or is designed such that it can just push it along in front.
-- Bukkakinator, Aug 05 2008


Too simple. There should be a job class of people who ride in the train sentinel, yelling at persons by the track with a megaphone and constantly glancing behind them, ready to pull the eject lever.
-- normzone, Aug 05 2008


For you sir, I recommend a book called "Einstein's Clocks, Poincare's maps. ~ Empires of Time" by Peter Galison. Completely crap, as is this idea. <he also manages to apply a few "work-arounds", post facto (a posteri), and it *is* related to signal transmission and detection.>

Theoretically, I should delete my first annotation, given the extra paragraphs added in the idea. But I won't. It takes a greater mind than yours to come to the conclusion that I am an idiot, as many before you have (including myself, but I may be mistaken).
-- 4whom, Aug 05 2008


so would the smart car have train wheels to drive on the tracks? if you reallly wanted to save fuel you could just use one of those pumper cars, you know the thing where the people have to pull up and down on the lever the the centre to make it go, and they're already designed to go on train tracks, so you wouldn't have to build anything new, it would really only be necessary in more populated areas with train track crossings, so in different areas you could have a team of sentinals in pumper cars who knew the train schedule, and would patrol the tracks when a train was comming and then radio directly to the train if they found something on the tracks that couldn't clear themselves.
-- ModernDivo, Aug 05 2008



random, halfbakery