Developing the mainline for your model train layout consists of a lot more than just laying a stretch of track from one yard or depot to another. Actually, planning the main should be included in the scenery section of information on how to build a model railroad. Freight yards are positioned on our layouts in those areas where we have space to build them and are always large, flat places. The nature of yards, with all of those turnouts and service buildings make them fairly easy to detail and scenic. Through tracks, however require some thought and planning to give them the look of reality.
The first decision to make is whether to create a single or double track main line. Double track construction requires more room and can eat into the available space for scenery. The obvious advantage is the ability to run two trains simultaneously in opposite directions without concern about the possibility of head-on meetings. A single track route can add interesting operation procedures at passing track meetings as well as maintaining strict running schedules.
Whichever option is chosen, the routing of the track should be planned so that it appears natural and realistic. Real railroads always planned their routes in the straightest and most level passage from one point to another. More often than not this was a course that followed a river or stream for great distances. The result was a line that contained numerous twists and turns and often needed a large amount of roadbed fills, culverts, bridges, and earth cuts. These were major problems for the railroad builders but present the train modeler with an abundance of details.
Unlike the real engineers, who laid out their routes to follow the terrain, we will lay out our track plan and then build the scenery around it. In doing this, we must have some idea of what we want the final scene to look like.
Now is the time to decide what geographical area we are going to model. Although flat, scrub brush landscapes are the easiest to portray, they do not have the scenic impact of mountainous country with its rock cuts and tunnels. With modern techniques and materials, it is not difficult to model rugged cliffs and thick forests like those found in the Pacific Northwest or Blue Ridge mountains.
Once we have defined the territory and have a mental picture of the scenery we want as a stage for our mainline, we can make a rough sketch and note the features. Draw curves first and describe the terrain that makes them necessary. Show tunnels, rock cuts, cribbing for containing rock falls, ditches, and any other outstanding scenic feature. Be sure to plan for enough clearance on both sides of the track-approx. 1” to the side of each outside rail.
With a little planning, the high iron can be interesting and highly detailed. We can think of the mainline as a series of interconnected scenes using tunnels, bridges and canyons as well as other scenic features as scene breaks.