Wednesday, July 11, 2012

"Deflection Test:" Can You Say "Oops?"

The Fair Train is a popular part of the Indiana State Fair. Operated by the Indiana State Transportation Museum on little-used track (originally on the now-a-bike-path Monon and it was quite a thing to see trains roar across the bridge over Kessler Ave.* Now it runs on another bit of trackage a few miles to the East that passes on the opposite side of the Fairgrounds from the Monon), it makes frequent runs from a station in Fishers to the State Fairgrounds and back, all day every day, during the Fair. There's plenty of parking at the Fishers end of the run, too.

...But recently, the normally pretty-good folks at Citizen's Gas replaced a gas main under the tracks at 56th St. Hoosier Heritage Port Authority, the outfit actually responsible for the tracks suggested 25 feet was the proper depth; Citizen's Gas smiled and laid the line seven feet down. The track operator promptly banned trains from operating on that stretch of track.

Today, the two organizations, having been induced to break the impasse, will be doing a "deflection test:" drive a train over the gas main/rail crossing and see what bends.

No smoking!
* That's the bridge that caused the change to a bike path; the city had been paving under it for over 80 years...and despite a sign giving the clearance, it had been a long time since anyone actually measured the height. A truck that was just a few inches under that limit went zooming under the bridge one day, and stuck. Even moved the bridge a little. The cost and trouble to replace the bridge was well beyond any practical figure, so hello, rails-to-trails. I believe the scrap iron prices of the rail paid for the much lighter bridge that now makes that crossing. Interestingly, IMPD drives over it sometimes when closing the trail for the evening. Is the bridge rated to carry a Crown Vic? I dunno. Hasn't fallen yet.


Tam said...

"Interestingly, IMPD drives over it sometimes when closing the trail for the evening."

By which feat causing rumors that there are at least a handful of sober officers on the force.

karrde said...

That's one test I'm not sure I want to be near.

How are they measuring the deflection? Do they have a way of running a camera down that nat-gas line? Or perhaps a laser that can measure if the lines bends more than allowed?

Random thought: I'd been told (by some guy on the internet...but an engineer, and someone who should know this kind of thing) that most buildings/bridges have a designed-in safety factor of 5.

That is: the "max-load" on the signs and original requirements is multiplied by 5. Then the structure is designed to handle this 5x load.

Don't know how this relates to natural-gas pipes, though.

perlhaqr said...

Scrap rail is worth a lot. Every time I'd tried to buy some, it's been very expensive anyway. Makes good anvils. Very resilient. (As one might expect.)