That machine is a tamper.

It rides on the track, which has perviously had ballast dumped upon it.  The tamper lifts the track and ties, and uses vibrating forks to evenly tamp clean ballast under, and between, the ties.  The ballast and the track sit on the sub grade.  Automated tampers like this can add superelevation on curves.  The little cart it is towing is used as reference for lasers that balance the machine to keep everything level and straight (or elevated and curved).  Those measurements are called cross level.

The process in its entirety is called surfacing.  It smooths out the ride quality of the track, and -- very importantly -- provides drainage through the clean ballast.

(Underlining provided for railway engineering terminology)

Last edited by Number 90

Number 90, Hi. I beg leave to differ with you, but the machine pictured which you describe as a ballast regulator is, in fact, a tamper, albeit one of the most sophisticated ones. This machine raises, levels and aligns track to its final "line and surface". The ballast regulator is a different machine although it often is seen with tampers. It can be identified by having a adjustable front plow to move the ballast into the track, out of the track, or across the track. It also has side plows, or ballast boxes, to plow additional ballast onto the tie ends for the tamper, or to shape the angular ballast shoulder to final profile. At the rear of the regulator is a large broom mechanism to sweep excess ballast stone from the track on the final pass of the machine. I have, in my past railroad career, operated a much smaller tamper, without the complicated electronics, and also a quite complicated ballast regulator, in my maintenance of way years, before moving to train service, before my 2016 retirement of 30 years.  Hoping to make things clearer. Don Francis 

@Don Francis posted:

Number 90, Hi. I beg leave to differ with you, but the machine pictured which you describe as a ballast regulator is, in fact, a tamper

Right you re Don.  Thanks for the correction, which I have made to my original post.

Tom right description wrong name it is a Tamper. Probably a Jackson 6700 or similar. A Harsco Tamper Mark III equivalent. The ballast regulator pictured by Genoz moves the stone around after the tamper does it's job. after several passes to line and level the track the regulator will lead with it's broom attachment and clean all the remaining stone off the ties. 

Looking at the original picture above note the stone is dropped level to the top of the rail nice and smooth. When the Tamper comes through it lines and levels the track. This is three dimensional action to line both ways. Hooks on the Tamper grab the rail and lift it as necessary and or shoves it left or right. The machine has Tamp heads that seriously vibrate and liquify the stone allowing this action to happen. The heads then drop into the ground and its fingers squeeze the stone when they get 1 inch below the tie. It applies about 60,000 lbs of force on the stone forcing it under the tie, stabilizing the tie and track into final position.  Now the stone is tightly compacted on this pass. The process for each tie is about 10 seconds. Very fast and very violent. These machines then to self destruct over time, it is one of the most expensive machines to maintain.  

Look at the stone behind  the machine and you will see it is almost gone, especially within one foot of the rail. The rule of thumb is one inch of raise requires 6" of stone on top or level to the top of the rail. You don't tamp the middle of the tie only within 12" in the rail.   So they may line and level it flat and then make more passes building super elevation into and out of curves. The ballast cart pictured above will be brought back in and drop more stone on top, and the process starts over again. That machine could wind up working the same piece of track 6 times. 

Look at the top of the machine, this is where the calculations are made. There is a Black board crossing the machine on the roof. That is exactly over top of the rail hooks, jacks and tamp heads. At the rear end of the machine are three receivers. They receive IR light from the projectors on the other end of the machine, located on the Bogie cart.  (when you took the picture the cart was not extended out the 62' cord length typical used for fine tuning track.) When they are using these computers the black board will block the light to the receiver and that tells the machine to stop raising or lining the track, which is now within tolerance of 1" per 31' of track, horizontal and or vertical for the speed this track will run at. The third receiver is on the side of the machine for lining. 

Newer machines I think run off of GPS and are a lot more sophisticated. The guys run back and forth over a segment of track a couple of times calculating all the rises and falls with pinpoint accuracy. they go back to the beginning set some parameters and let the computers take over and let the machine run in full auto. 

Typically where ever there is a Tamper there is a Regulator close by. You can go on U Tube and see videos and time lapse video's of these beasts in action. The main lines run even larger machines that do 4 ties at once. I remember a good time lapse of a train wreck site in NY or NJ where a passenger train wrecked on a water front. They show these machines going back and forth repeatedly for days.  



Just a suggestion; you might want to edit your thread title to something more related to what is actually going on. Such as "Laying new track in San Diego", since they really are NOT "Building new rails" (the actual rails were 'built/manufactured' at a steel mill someplace else).

@Genoz posted:

I thought I’d share an interesting experience with you all watching these machines. I received so many negative comments, from my spelling to the title of my thread. Lighten up. I won’t post anymore, I promise.

Well, I guess if you aren't willing to learn, then that is always your choice.


Hi claw bar, What we in MOW called idiot sticks was shovels or ballast forks, but I suppose it could also be lining bars.

Hi Genoz. Don't give up, stick around. It can be frustrating at times, but there are good folks here. Hopefully no statements of mine were offensive. Don Francis

HI Don

Yep!  Long heavy iron tamping bars used to tamp ballast after replacing ties and/or rail and raising track!  Go thru a pair of gloves real fast !





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