Consider Degroots Spire arborvitae or North Pole arborvitae.

Degroots Spire evergreens can make a nice thick and narrow hedge of trees. They also can be used alone as accent trees or to soften the look of hard lines or corners often found in buildings. They are expensive, but will be well worth the investment if you purchase ones that are 5-6 feet tall, B&B ones that have been potted in 25 gallon containers, while being left in their burlap. Ask your nursery man how far to space them for the screening affect your desire. If the soil where you want to plant them drains fairly quickly then make certain to keep them watered when the rainy season is over. Do this summer and winter at least for the first three years after planting, and there after if you see any of their inner, or even worse, lower leaves turning brown. They probably would suffer too much of planted in soil that stays saturated for long periods of time.

Thank you so much!!! That's the plant I've been seeing around and couldn't find the name! Thank you :)

I would definitely suggest something deciduous for a western exposure, so in the wintertime the bare branches will allow the sun to warm your house and assist with your heating bill. Crape myrtles are a good choice, we had some along the fence at our old house that were 15-20 ft tall, but they were more shrubby than tree like, IMHO. Perhaps it was the early pruning or lack thereof, they were likely decades old and technically in my neighbor's yard, so we couldn't do much to make them more tree-ish at that point.They were also really prone to powdery mildew because they were not pruned much. Consider how much you will be using the west side of your house - if there are patios or doorways you use a lot - crapes attract lots of wasps and bees in my landscape, and I'm seriously allergic, so I don't have them planted close to where I like to be. I would also suggest my very favorite tree, Chinese Pistache, which we planted in our yard and loved. It is a beautiful small shade tree, reaching 20-30 feet wide at maturity - so you could plant it close to the RR ties and have 10-15 feet of canopy on on your side, and 10-15 feet of canopy on the neighbors side (assuming there is a similar amount of lawn strip over there.) The trees have a beautiful shape, fall color, pretty berries, and small leaves (no raking for the win!). I'm finding places at my new house where I want this tree to go when I put trees in the ground this fall/winter. Redbuds might be a good choice, too. They are a little smaller than the Chinese Pistache in the canopy - 15-25 ft - and they flower at a time that there are not a lot of wasps active, plus the flowers are usually way over my head, so I'm not quite as cautious with them. Here is a link that might be useful: Chinese Pistache and other trees