100-85

[Outback]

Maybe you've seen this before but I thought this was interesting so thought I'd post up pics for those who werent "in the know".

These shots are of proto rail joints between different guages of track. 100 lb rail (L) to 85 lb rail (R).

It would seem that the branch line is 85lb while the town trackage (station, elevator &c) is 100 lb. These stepped joints are used to join the two.

I have never noticed these things before, so to me it was interesting.

D

 

[SABRR]

Those are around the country more than you think. Many of the sidings, service spurs, rip tracks, team tracks, etc., were built way back in the steam days. The closer you get to the year 1900, the less poundage the rail would be. Many areas still work with 85 lb. rail or less, thus restricting the motive power to 4 axle diesels. Railroads will use 6 axle when they have no choice, and they realize the risk they are taking. Usually nothing happens, but to run a 6 axle on the smaller pound rails will usually bring about its demise, and cookie-cutter rail replaces it.

 

[Rico]

Those are called "compromise bars" and come in a set of four. They also come in all kinds of sizes and seldom jump from more than two rail heights so you can sometime find three or more in a row coming from mainline 136lb down to 70lb in some cases.
The inside two keep the rail head aligned, the others keep the rail pushed over to match as in the first photo. (the webs would not be centered like MRR rails)
Most railways use heavier rail for road crossings, bridges, or extended curves.
Railroads often paint them blue or another color so equipment using flangers or plows can adjust to the differing rail heights so as not to take out the ties.
Looking at those pictures I'd guess they are on CP track by the staggered bolt pattern.
Where the two rails meet in the photos they are dipped down, a condition known as "end batter", that gives us our beloved clickety clack.
Sorry for over analyzing this!

 

[Cjcrescent]

While todays SD's surely are the monsters of the mainlines now, when 6 axle roadswitchers first came out, many were designed for lighter rail. Hence the name Special Duty, or SD. The 6 axles spread the weight of the locomotive such that there was no damage to the lighter rail. The early SD's had lighter axle loadings than the GP's and could be used on lighter rail easier than the GP's.

 

[Outback]

That's some interesting information Rick and Carey. They say you learn something everyday - today was no dissapointment.