Do You Need Blocks with a DCC System?

May 23, 2017

This article kindly contributed by club member Jim P.

If you grew up with a DC system, then you will be familiar with the term “Blocks.” Having blocks on a DC model train layout is basically the process of separating the railroad trackage into sections, so as to control one locomotive independently of another loco in a neighboring block.

If you think of how real railroads operate, they typically divide mainlines into blocks, which are assigned signals to keep railroad traffic on the right track and at a safe distance or separation.

The question that often gets asked is, “Will I still require blocks with DCC?”

In theory you won’t need blocks as in the conventional sense. However, with DCC systems, blocks are regularly utilized to operate signal systems as well as to isolate problems. Blocks are necessary when using block detection, or polarity reversing sections i.e. wyes, turntables, or balloon tracks which are like a big loop tracks with a single switch to enter and exit. It’s worth noting that a reversing section will need to be at the very least the length of the longest train. This is especially so, if the train has passenger cars, or a lighted caboose.

Blocks for that purpose might be sufficient on some small model railroads, but incorporating more blocks would be beneficial on bigger layouts. Having additional blocks would certainly prove an asset on a layout operated by more than one person, or for one that is larger than would fit onto a standard sheet of plywood. Take it from me… it is so much easier to troubleshoot and isolate problems with blocks in place.

That said; a typical DCC layout won’t usually require as many blocks as would have been necessary on a conventional DC layout, but having some blocks will at least make it easier to locate and fix problem that might otherwise be difficult to pin down. Besides, without having blocks it might be necessary to shut down the entire DCC layout if there’s a short… and that not something any of us would want to do.