To study your site options beforehand, use GoogleEarth. Zoom in to Altamont, make sure the compass is rotated so North is straight up, and you'll notice that the track runs from southwest to northeast. Now, consider that this time of year, as we approach the Vernal Equinox, the morning sun will be appear on the horizon almost directly to the east. As it rises in the sky, it will also arc progressively toward the south. At mid-day, the sun will be lighting your scene from the south. By mid-afternoon, the sun will be shining from the southwest, aiming almost directly in-line with this segment of track. Later in the afternoon, the sun will shine more from the west, thereby lighting this segment of track from its north side. Taking all of this into account, if you're looking for light that will best capture the colors of the train, you'll basically want to shoot from the south side (highway side) of the track in the morning, or try to gain access to the north side of the track in late afternoon. With GoogleEarth you can zoom in to different vantage points, tilt the view angle, and spin the compass direction to get an approximation of your photography options. There's also a time-of-day simulation feature, but it does a better of simply showing where the sun will be in the sky than it does of showing what the actual shadow directions and quality of light will be.