Manual blocks and reverse traffic

I recently was asked some questions about

Manual blocks

(and this post got long… you might want to go make a nice sandwich or something for yourself before settling in to this one)

When train movement on one track is not available, a manual block is used to move trains on the adjacent track. This could happen because of planned maintenance, or it could be done in the event of an accident/emergency situation. In a manual block, Control directs train movement in both directions on the track that is in service. Manual blocks will have associated train orders.

You’ve done the equivalent of a manual block in your car before if you’ve gone through road construction where only one lane is open. For cars in that setting, there’s a flagger at each end of the construction area that lets a number of cars through and holds oncoming traffic from entering the single lane, and then they switch to let cars from the other direction go through. A manual block for trains is essentially the same idea – Controllers and supervisors coordinate to govern train movement into a manual block, alternating between trains running normal traffic (e.g. east in the eastbound) and others running reverse traffic (west in the eastbound).

Reverse traffic

Borrowed photo. This is not a manual block, but it shows a train running reverse (here east in the westbound at Willow Creek)

Running reverse traffic is not the same thing as backing a train up. An operator backing a train up (such as in the case of uncoupling a train car) can’t see in the direction that the train is moving – this is why backing a train up is almost never done. When an operator is running reverse traffic, they face in the same direction as the train’s movement, but that movement is in the opposite direction of what the track they’re on is typically used for.

There are a number of rules that govern running reverse traffic. First, it’s always done at restricted speed (the lesser of 20mph or the posted speed and always at a speed that the operator can stop in half their sight distance) whether or not it’s part of a manual block, unless you’re in the tunnel. Because the tunnel is signalized in both directions, trains running reverse can operate at the posted speed limits which are about the same as normal speed limits, though trains going west in the eastbound bore will exit the tunnel much slower than normal traffic because they will be diverging into the west portal pocket track. Other areas of the alignment that are signalized in both directions are already single track, e.g. the “fishhook” for the Red Line at Gateway, so travel in both directions is normal.

While running reverse, operators will also have to stop and observe every set of switch points to ensure they are properly aligned. In ABS territory, running reverse traffic is where dwarf signals come into play – they protect mainline power switches while running reverse traffic. In other words, the ATS magnets associated with the dwarf signals are active for trains going the “wrong way”. Operators will have to key-by these signals (this is done from the operating console in the train cab) after calling Control. This gives the operator 23 seconds to move the train past the ATS magnet without tripping.

On Burnside, operators running reverse traffic will have to SOP the intersections since the mass detectors are only for normal traffic. If the reverse running on Burnside is part of a manual block, the train orders associated with the manual block will include instructions to SOP intersections within the block. So operators will not need to call Control for permission at those intersections, but otherwise the process to SOP them is the same – stop, wait for fresh parallel green and walk signal and red left turn signal, sound horn warning, and proceed when safe.

You may have seen these stop signs at gated intersections or in places where the view is obstructed by a substation building – these are for trains running reverse traffic since people are not likely to expect a train from that direction on that track.

Gated intersections are also handled differently when running reverse traffic. When running normal traffic, the gates are lowered either by a call loop if the platform is right near the intersection (such as the above picture of Elmonica/170th) or when the train enters the approach circuit as it approaches the crossing gate for gates that are not near a platform. There is another circuit that extends 10 feet on either side of and through a gated crossing called the island circuit. When the island circuit is shunted, it will lower the crossing gates if they weren’t already lowered – you won’t notice this running normal traffic since under normal operations the gates will be lowered by the time the train gets there, but when a train is running reverse traffic, it uses island circuits to lower the crossing gates. The operator will wait until the gates have been fully lowered for 10 seconds before proceeding through the intersection.

Manual Block

In a manual block, most of the rules that apply to trains running reverse traffic will also apply to those running normal traffic. For one thing, travel in both directions of a manual block will be done at restricted speed, unless otherwise instructed by Control.

Borrowed picture – Both of these trains are running normal traffic, but it shows switch points as the operator sees them. Here it is a trailing move since the points are facing away from our oncoming train

If there are switches in the manual block, operators in both directions will be required to stop and observe every set of switch points before proceeding, regardless of whether the switch points are facing toward the train or away from the train (as seen in the above picture).

A planned manual block will have a written train order, but operators about to enter a manual block, whether planned or unplanned, will still call Control before they enter to receive specific instructions. The instructions will have to be repeated back word for word, which ensures that there is no misunderstanding of the instructions, since manual blocks have the potential to be extremely dangerous. Even at 20mph, a train splitting a switch (making a trailing move over a power or t-rail switch that isn’t set for you) or hitting another train can cause serious damage. The specific details of the instructions may vary depending on where the manual block is and why a manual block is in effect – for example, a planned manual block may have pullback operators to pull the train through crossover switches so that the operator of the train doesn’t have to change cabs.

Previously, a “medallion” system had been used for manual blocks. A medallion was an object such as a stuffed animal (like the rabbit) that would be passed off to a train as it was about to enter the block. If you didn’t have the medallion in your possession, you would not enter the block. Nowadays that system isn’t used. Instead, a clearance sheet is used to record all train movement in manual blocks. This written record details the movement of all trains into, through, and out of the block, ensuring that only one train is in the block at a time.

Once an operator is clear of the block, he or she will call Control. Their train will be recorded on the clearance sheet, and the operator will then be able to resume normal operation. The next train will then be cleared to enter the manual block. This process continues for the duration that the block is needed. At that point, Controllers and supervisors will ensure that all trains are clear of the manual block and that all switches are aligned normal and locked. The first train through the track that had been out of service may be asked to sweep that section of the alignment, especially if the manual block was due to an emergency, and then following trains can operate as normal.

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5 responses to “Manual blocks and reverse traffic

  1. As always, a very informative post!

    In the year you’ve had this blog, I’ve learned so much!! Thanks!!

    Matt

  2. Yes! :)

    23 seconds is sort of a random number, though..

    • Yeah, it’s sort of like the 17 seconds / 4 min 17 seconds of a time lock switch. It’s an unusual number, but I guess that makes it easier to remember. It’s long enough though. The part of the train that the ATS acts on is about halfway down the train car (there’s one associated with each cab) and only the one associated with the leading cab is active, so 23 seconds is plenty of time to get the first half of the first train car past the ATS magnet.

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