The Railcraft mod enhances the rail system in Minecraft. It takes it from a few simple tracks to a full blown railway by adding more tracks, carts and even a train engine. You can now do pretty much anything you can imagine with rails and if you like building trains and coasters in Minecraft, you’ll love this mod.
train
There are a few higher speed tracks that give you a significant boost over traditional tracks. The High Speed Track is unpowered at 2.5x standard and the High Speed booster track significantly boosts the cart speed to 125%, which can be very dangerous. And the Launch Track is more fun than practical as it will launch your cart into the air. It’s great for jumps or if you want to make a creative entrance to your home.
HighSpeed
Launcher
There’s a great new Reinforced Track, which is both faster and nearly indestructible. It’ll help to ensure that your track will remain intact and won’t be susceptible to creeper blasts or damage from Ghasts in the Nether.
reinforced
The elevator track allows you to place tracks vertically and will lift or lower an attached minecart. This is a fantastic new system for creating an elevator rather than using a clever hack with ladders or water. It’s great for loot delivery as well and also functions as a regular ladder you can climb.
elevator
Switch tracks will allow you to create a railway similar to real life. You’ll now be able to manage the direction of rails and switch their tracks whenever you need to. You can even automate the switching with a switch motor.
Switcher
The Work Cart is a great asset if you need a quick crafting table while working on your rails. Say you’re building a rail in the middle of the ocean and need a crafting table. Well this one will roll with you.
craft
There’s an incredibly handy new cart that will replace existing track with whatever you set it to in its inventory. So if you wanted to quickly swap out some old track with new ones from this mod then this cart will streamline the process for you so you won’t have to manually destroy and re-lay all that track. You’ll need to link it to a chest cart that will store the track you want to lay. The relayer will then pull from the chest and replace the old track with the new as it chugs along.
relayer
And one of the coolest additions to this mod is the Tunnel Bore. This will make the process of digging your tunnels much easier. It will do exactly as its name suggests and bore a tunnel for you in a mountain or any length of wall you need track to go through. And it will hold a stock of rails that you want it to place as it goes. Load it up with gravel in the Ballast inventory and that will provide ground if it encounters none along its path.
bore

Reference the wiki here for more tracks and fun items with the Railcraft mod.