http://www.rail-videos.net/video/view.php?id=1352
If you watch the video, it this common to see the bouncing?
It looks like it was shot with a telephoto lens which will magnify the effect. Watch a train at a highway crossing. The rail roadbed doesn’t settle as much on the highway or settles more on either side. That makes a mini roller-coaster effect. It’s fairly common. When it gets bad, they’ll put in a slow order until the line can be lined and surfaced.
Yup. All she needs is a good run over with a tamper and a regulator and it’ll be good again. Worst case scenario add in some new ballast and slurry injections to firm up the 'bed and choo-choos will be running over it again.
On a side note, whoever took that video is an idiot.
The TRAINS DVD about Rochelle shows some significant bouncing, particularly on UP, as trains cross the diamond.
Some of our track probably needs surfacing - we can get to swaying in certain areas. We’re on jointed track with the joints staggered and depending on our speed, we can do quite the dance.
Dramamine, anyone? It is amazing how much rockin’ and rollin’ can go on – as tree said!
There are very definite standards for track alignment, depending on the class of track (which, in turn, limits how fast you can go). Problem is, most often the alignment checks (cross level, superelevation, profile, etc. etc.) are made with the track unloaded – and if the roadbed is iffy, the track can move a surprising amount as a train goes over it. Working on it…
Definitely telephoto lenses distort the rock and sway. But, there are such dynamics built into the system based on several cause factors including wheel flange thickness; wheel flatspots; car size by height and width; car load and/or overload and type of load; speed limit vs.actual speed; track surface including rails, type of rail, joints if any, in or out of guage, ballast condition, grade crossing, switches and frogs, drainage, maintenance or lack of;. And I am sure there are many more dynamics I haven’t even thought of.
Two stories, one about sway, the other about leaps. About 30 some odd years ago riding cab with a freind had several cars loaded with salt. We were doing track speed of about 30mph when overloaded car begans to sway because of track dynamics…therefore speed had to be reduced to below 12mph by timetable rules. At about the same era we were on the road alongside the PC’s Wilkes Barre to Sunbury, PA line when a southbound came at us at at least 50 mph…seemingly higher than track speed. The the whole train seemed to leap across out of guage and low spots in the track; because of the speed it seemed to stay in a straight line rather than sway sideways or go off the track entirely!
Telephoto lens distortion has already been mentioned. Secondly the video compression algorithm used to reduce the video file to a size that can be effecitvely handled over the net also enhances the perceived movement.
However the movement might have been enhanced by the lens distortion or video compression, I think I would have put myself a little farther the right of way for that train. But then I am somewhat chicken hearted when it comes to speeding freight trains. [:-^]
Maybe the crew are shaking up their martinis in the cab; did James Bond like his martinis stirred or shaken–I can’t remember!
from a prior post: “The TRAINS DVD about Rochelle shows some significant bouncing, particularly on UP, as trains cross the diamond.”
That site uses a fixed-place “frog” so some amount of thumping is inevitable. - a.s.
That’s nothing, you should have seen the Modoc line in it’s last days [:O]
I’d say it’s not so much the track as it is the engines. I know our worn out SD’s are known for severe lateral motion. Some of our newer units are too.
Are there any test cars, that test the track alignments under load? Granted, a test car like that would be as heavy as a loaded car!
Don’t Sperry Rail Car’s have capability to “test” the track structure under most conditions…
Sperry’s speciality is rail defect detection. The Class I’s all have their own Track Geometry testing cars. The FRA also has at Geometry Testing vehicle that travels all over the country testing.
The tracks don’t look in bad shape, trains do bounce more than people realize. I have seen this on well kept lines. If you ride a passenger train and sit with a view of the rear of the engine, you will notice it moves a lot more than you can always tell from outside. Now on a badly maintained stretch of track I’m sure its a whole different story.
Train cars at slow to moderate speeds tend to rock left to right. At high speeds, they are more likely to hitch forward and back. - a.s.
Here is one of the FRA track inspection cars. Made in Austria.
UP has one similar car.
I think both of these have a Gage Restraint Measuring System on them. A roller puts outward pressure on the rail, trying to spread the rail out. The system measures how far, if at all the rail moves under load.