DCC v DC; Pros and Cons

Hall Royd Junction Box nameboard as preserved at the East Lancashire Raiway, Bury

NEW! Upper and Lower Quadrant 2mm signal transfers!

The pros and cons of DCC

Pros	Cons
1. A two-wire bus feeds all tracks without the need for isolated tracks and associated wiring and switching.	1. Some track schemes such as balloon (reversing) loops require reversing loop modules. I use 4' baseboard modules, and the reversing section has to be as long as the longest train. In my case this is 12 foot, and that means that six wires have to cross two baseboard joints. Also, for optimum operation ideally every single piece of rail needs to be bonded (connected) to the bus wires, as in DCC the fishplates cannot be relied on to provide a reliable electrical connection.
2. All DCC equipment conforms with NMRA standards, so gear from different manufacturers can be used together.	2. There are latent incompatibilities, and some gear cannot be used universally e.g. Gaugemaster reversing loop modules work well with the Lenz compact, but fail with the NCE Powercab, as the latter has a faster cut-out.
3. New loco decoders can be bought for as little as £9 on eBay.	3. You get what you pay for, and low-cost decoders do not perform as well as the more expensive ones from vendors such as Lenz and Zimo. The more expensive ones can handle higher amperages and offer cut-out protection, so are less likely to blow.
4. DCC allows realistic operation, as it allows multiple locos to occupy the same track, and they can be run easily together so allowing double heading or banking. It is possible to attach or detach vans from a train standing in a station using the station pilot.	4. Creating isolated sections in DC is time consuming and means that locos or trains have to stand at pre-determined locations to be isolated. If multiple train operation is required (more that one running line) then a controller is required for each line, and trains cannot be easily switched between them if trains are running.
5. Every loco and accessory (points and signals) have their own decoder so they can be controlled from a single device (so like a TV remote that works the TV, DVD and turns the lights on and off).	5. Equipping 50 locos with a quality decoder will cost around £1,000; a good DCC system around £250 and 50 signals and points with 13 accessory decoders,will cost around £400. If the polarity of point frogs also need to be switched then a Hex Juicer will do the job very well at a cost of around £80 for six points. So assuming a reasonable sized layout, new entrants should budget up to £2,000.
6. Wireless and computer technology allows great flexibility with trains and points operated by taping a diagram on a screen which no-longer has to be in the same room as the layout.	6. Wireless and computer technology can introduce great complexity if the user is not tech savvy. See the very good forums and discussion groups to get a feel for some of the problems encountered.
7. Converting a loco to DCC is easy: just take the body off and plug the decoder into the factory fitted socket.	7. DCC is much more hyper sensitive to short-circuits. This is particularly so with kit-built locos, and a loco that runs well on DC may not run so well on DCC. By way of example, a Bachmann split-frame Jubilee I converted ran on DC, but refused to work on DCC. The problem was a low-grade path created by the metal casing of the motor, which had to be removed and the casing covered in insulation tape. Locos that do not have a socket either need a socket fitting or the decoder has to be hard-wired into the loco. Either way, the harness comes with a lot of wire and squeezing this into an already tight space within the loco body can be tricky.
8. Locos only move when they receive an appropriate command from the throttle, and are fully controllable.	8. The nature of the technology means that track and wheels need to be much cleaner than with DC. Tender locos are much improved with tender pick-ups, whilst 'stayalives' help locos with short wheelbases. DCC locos are regularly reported as 'shooting off' out of control, despite being told to stop. To stop this, locos should be programmed on the layout they are going to operate on, and DC should be disabled. Likewise, European chips with Railcom (Lenz) should have it disabled when being used with a US control system (NCE).
9. When a short circuit occurs (e.g. running through a point set against the train) the circuit breaker trips. With the NCE Powercab this automatically resets once the short is removed.	9. Short circuits create a spike which is 'seen' by every decoder on the system. If the cut-out is fast, no damage will result. However, spikes are not good as they can cause some chips to reset to '3', so that they don't work when selected, and need re-programming. In the worst case scenario, the spike can blow a decoder, and I have had a Hornby sound chip blow. I now keep the sound chipped locos off the 'main' unless being used.
10. The cut out quickly detects short circuits and closes the system down.	10. Trying to find a short on a large layout can be a real pain! And it can be caused by something really silly. My layout is modular (boards bolted together), and I have installed a simple on/off switch at the throttle-end of each board, through which the bus wires are fed. That way, when a short occurs, it is possible to isolate a baseboard one at a time until the one with the short is located. It should now be apparent that for something billed as 'only two-wires', there are extra wires and switches required that you don't need in DC!
11. DCC works very well with points where the blade and the stock rail have the same polarity, so there is no possibility a short circuit caused by the passage of a wheel through the point causing a bridge between the positive stock rail and the negative blade.	11. Peco are the leading supplier of ready-made finescale track but the design is essentially a DC one, and for totally reliable DCC operation a number of modifications are required. Ironically handmade points using copper paxolin sleepers are ideal for DCC.

Would I do it again? I like prototypical operation, and I like the ability to be able to move locos in way that corresponds to how they would have in real life - helped by the fact I've modelled an actual location where trains were reversed on the main line, and also from which bankers worked.

I also use points and slips with live frogs, so DCC allowed some complex switching to be eliminated (I would have needed a rotary switch in DC). It also allows reversing loops, so in the round it has been worth it.

But if you don't like computers, then switching to DCC will introduce extra complications which may significantly impact on your enjoyment of just running trains.