On this latest trip to Japan last November I had noticed what appeared to be a row of concrete tiles running alongside the tracks. It took me awhile to realize that this is actually a duct for all the signal and communications cables on the railroads. At a grade crossing or some other obstacle it appears that pipe carries the cables to the other side where the tiled duct starts again.
This would be easy to scratch build something like this using Evergreen tiled sheet styrene sprayed a concrete color.
Then recently I noticed this Kato kit on ebay. They refer to them as gutters and that would suggest that they are for drainage. Either way, they make a nice and easy detail to add to a layout.
I'll be adding this detail on both the Musashi-Koyama modules and the Hot Springs Junction module and using both this kit and some scratch built versions.