Signal Blocks

[mp202]

I have a question, what is the average distance between signals or the length of a signal block? And what is the standard signal used on US railroads in the 90's to present.

-Blake

 

[fran1]

I doubt there is an average length, it will all depend on the types, lengths and weights of consists using the route, it's line speed and the headways between consists. So many variables to factor in.
The slowest to stop from line speed will dictate the minimum length of a block.
The busier the line the more blocks there will be to keep traffic moving.
I could go on but you get my drift.

 

[Koryclarke1991]

I usually space mine 2 miles apart, which is the standard norm, use the ruler to measure 10,560 ft. which is two miles

 

[sniper297]

Varies according to what runs on the line and how often. Where I grew up in Chicago the Lake Street Elevated ran parallel to the Chicago & NorthWestern Galena line - the elevated route ran 6 to 8 car rapid transit trains, block signals were 1/8 mile apart because the trains were short and accelerated/decelerated quickly. The C&NW spaced their block signals 1 mile apart, with mixed passenger, commuter, and long freight trains. Way out in the desert you might see blocks as long as 5 miles, it all depends on how much traffic and what type of traffic.

 

[cascaderailroad]

There is a NYC transit video that shows fixed block signals, that only allows a train to enter the next block, that is 2 blocks in back of a train that is in front of them ... But they are now upgrading to traveling block signals in each train, that travel along with the train, and allows many trains to bunch together much closer.

I place most of my signals by placing them in excess of a 1 1/4 mile long train ... that way my 1 mile long trains stay very separated

If one was doing a subway route your blocks would be much closer together, a tad longer than the average subway train consist

 

[JCitron]

There is a NYC transit video that shows fixed block signals, that only allows a train to enter the next block, that is 2 blocks in back of a train that is in front of them ... But they are now upgrading to traveling block signals in each train, that travel along with the train, and allows many trains to bunch together much closer.

I place most of my signals by placing them in excess of a 1 1/4 mile long train ... that way my 1 mile long trains stay very separated

If one was doing a subway route your blocks would be much closer together, a tad longer than the average subway train consist

I make my blocks the same way. A 2000 ton US coal train consist is a good length for blocks I found out between permissive signals. On my trolley route, I make them substantially shorter.

 

[justinroth]

Modeling Columbus Ohio I have found NYC spaced theirs a mile and PRR/N&W two miles, at least around here. It's situational. As far as signals I have some modern ones on the DLS, safetran variations.

 

[ctclark1]

Modeling Columbus Ohio I have found NYC spaced theirs a mile and PRR/N&W two miles, at least around here. It's situational. As far as signals I have some modern ones on the DLS, safetran variations.

They've also changed over time... As CSX installs a new signalling system across New York State on the old NYC Mainline, they are primarily using the existing locations as the basis, though with some adjustments based on a new braking profile for the trains. The Central's spacing for the CTC (centralized traffic control) installation in the '50s was roughly 2 miles in most places, but I've read somewhere that before CTC (and removing 2 of the 4 tracks from the main) that the original 4-track block system was closer to 1 mile in some places...


Another very important point is that most times, the spacing was not exact to the foot. Curves, hills, and other obstructions would affect the spacing (for sight and braking distances), also it would have been roughly based on the distance between the two interlockings that the auto-blocks are being installed into... If you have a distance of 6.7 miles between two interlockings/CPs, you're not going to install the autos at exactly 2 miles apart and have one block only be .7 miles before the interlocking.... You'd probably still have 3 blocks in between, but they might be spaced more along the lines of 2.2 miles in this stretch, while the next stretch, between the 2nd and 3rd interlocking (say, a distance of 7.3 miles) might have 3 blocks spaced at 2.4 miles, or 4 blocks spaced at 1.8 miles... plus still taking into account the adjustments I mentioned above for sight and braking issues, so even within that set of blocks you might have spacing of 2.2, 1.9, and 2.1 miles...