will an electric train set shock you if you touch both rails at the same time? - Model Railroader Magazine

Short answer, no, at least not with a 12v DC set (like the majority of HO and N sets). Even on the 24v? AC used for large scale digital setups you'll just get a nip - not enough to harm you. I've had more than a few and I'm still standing. The power supplies we use are carefully regulated to avoid putting enough power onto the rails to hurt us.

There was, once, in the jurassic era of model trains, an electric train that ran directly from the 240V AC mains current. It was made by Hornby and was their first electric loco, a model of a London Underground 4-axle electric loco in O (it'd be described as a boxcab on a US line, two of the real thing are preserved). It was quickly withdrawn for obvious reasons (allegedly there were government objections), and Hornby went over to 6V, then 20V, then the 12V DC that we still use today. The original sets are now highly prized collectors items despite their lethal tendencies. There may well have been others at the same time, but this was around 90 years ago.