This method requires an active signaling system. The same power used to turn the block signal to red is the power that activates the system. Below is a simplified schematic on how it works.

As you can see, the rest of the layout is block-detected. The braking section could also be block- detected, but we excluded that for clarity of the relay wiring. The bulbs wired in series with the DC power supply are 1157 automotive bulbs. They're there for electrical protection of the DC power supply, and allow the DCC power to be dominant when a loco is crossing the gaps - don't do this without these two bulbs.

The relay is a Double-Pole Double-Throw (DPDT). The two connections on the left are for control. Applying power here will trigger the relay. The next two connections are called N.C., for Normally Closed. What this means is that these two connections are connected to the next two "common" connections when there is no power to the control pins. The right two connections are called N.O., for Normally Open. When power is applied to the control pins, the N.C. connections are disconnected from the common connections and the N.O. connections are connected to the common connection.

When the red signal is not lit, there is no power to the control pins. This connects DCC power to the braking section. When a loco crosses this section, it will continue to run as if there were no braking section at all. When the red signal is lit, the same power activates the relay. This disconnects DCC power from the braking section and applies DC power. Here comes the final piece to the puzzle.

There are decoders that have a special feature that makes this work. First, the decoder has to have the capability to program Automatic Analog Conversion to not work on an analog layout. Next, it has to have a feature where the decoder will use the momentum programming to bring the loco to a "momentum" stop when power switches from DCC to DC. If the braking section has DC power applied when the loco enters it, the loco will slow to a stop according to the deceleration momentum programmed into the decoder. When the signal's red light goes out, the relay re-applies DCC power. When this happens, the decoder will start up and accelerate, using the acceleration momentum, to the speed it was going before it stopped.

That's the short story. There are pros and cons for this type of braking section.

The primary advantage of this method is cost. For only a few dollars per braking section, it can be effective. One minor disadvantage is the complexity of getting around some of the things listed below. The primary disadvantage is that it won't work unless all of your decoders have this feature. While all Digitrax decoders have this, the ones most people have that won't work with it are Throttle Up!'s SoundTraxx decoders. Even if they did have the analog momentum feature, the sounds wouldn't work.

But, if you think this method is for you, there are several things to think about when designing your braking sections.

The braking section has to be longer than the amount of space it takes the loco to stop according to the braking momentum programming. Obviously if it takes the loco four feet to stop, the loco will continue on through the braking section onto the occupied block. When it hits the block with DCC power, it will accelerate and keep on going.

The braking section must be long enough past the signal so that if the signal turns red when the loco is in the braking section, that it will still stop in time. However, if you have this situation, you either have an intersection in the block (such as a siding), or you're about to have a head-on collision.

You also need to make provision for MUs, if you do MUs. If the braking section is set for DC, the first loco in will be wanting to stop while the next loco, still on the DCC track, is still trying to go. This can be accommodated in many ways. One way is to install a short isolated track about six inches before the end of the mainline going into the braking section, as shown below.

Notice that, from the mainline going into the braking section, a loco crosses gaps into a short section connected to the braking section, then crosses gaps into the next short section connected back to the mainline, then into the braking section. The idea here is, with MU lashups, there will always be a loco crossing gaps until they are all into the braking section. When a loco is crossing the gaps, the dominant DCC power continues to control all the locos - meaning that none of them begin to stop until the last loco is completely inside the braking section. And remember, once the entire MU gets into the braking section, it must still be long enough for it to stop.

Now, you may or may not need this extra bit of wiring. It all depends on how many locos you MU, how your momentum is programmed, etc. Here's why:

Once the first loco is in the braking section, it will begin to stop. But, when the second loco hits the gaps, the first loco will again start to speed up. That's because when the second loco crosses the gaps, the dominant DCC power takes over again. Once the second loco is completely within the braking section, they will both start to stop. If you have a third loco, as soon as it straddles the gaps, the first two will again begin to speed up. This continues until all locos are within the braking section.

If you have braking momentum to bring the loco to a stop fairly quickly, you will probably see some bucking. The extra wiring shown above should reduce that bucking. The nifty thing here is that you can rig it without the special wiring. If you have a bucking problem, you can cut the extra gaps and wire in later.

Lastly, there are many configurations of the type of relay shown in the first illustration above. They can be purchased at most electronic surplus stores for a few dollars, and Radio Shack has some for a little more. While all DPDT relays will have the same connections (Control, common, N.O., and N.C.), not all have the same pin out (connection positions). The one(s) you get may be different than the pin-out illustrated above, but you can figure it out. First identify the coil (control), then the common connections. Next identify the N.C. connections for the DCC power. Connect the DC power to the N.O. connections.

Using the Chief's braking section feature is similar to that shown above. The difference is that instead of introducing DC power to the braking section, it introduces a DCC all-stop signal to the locos inside the braking section. The advantage of this is that it doesn't require a decoder with the special DC analog feature, and SoundTraxx sounds will continue to operate properly.

As you can see, the wiring is identical. The only difference is that the braking power is supplied by a DB150 slave booster instead of a DC power supply. The DB150 booster must have its own 5-amp power supply, and be connected to the Chief's programming track output for the braking section. It also requires you to set the Chief's OPSW to operate the programming track output as a braking section controller when not in the programming mode.

All the same issues apply, including length considerations and special wiring if your MU bucks when entering the braking section.

With this method, the computer controls the signal: the computer knows when the signal is red. When the block detector detects a loco in the braking section, the transponding receiver reports the loco's transponding ping to the block detector, then the block detector reports the loco's address to the computer. The computer then brings the consist to a stop - not by sending an all-stop, but by gradually throttling the consist address down to zero. When the red signal goes off, the computer then throttles it back up.

With this method, there's no concern about MU bucking because the entire consist is controlled by the computer. While there's no concern about the loco running past the braking section gaps and starting up again, if the train does run past the gaps it would keep the signal from switching away from red, and never start up again. This has to be accommodated - either by insuring the braking section is plenty long, or by introducing another detection block to let the computer know that the loco MUST stop NOW.

While this method doesn't have a lot of the concerns the other two methods have, it does require a lot of specialized equipment to be installed, and tweaked to work correctly. It requires BDL162 or BDL168 block detectors, RX4 transponding receivers, and transponders (or transponding decoders) in at least the lead loco in the consist.