You will have to use the fork lift truck once again. Head on to the nearby stairs (#1). Don't worry, you will be able to enter the new corridor without any problems. You will find yourself inside a fake tomb. Turn left (stay on the fork lift). Start off with moving two of the nearby crates (they are blocking your way). Now you will have to hit this wall at full speed (#2).
Stay inside the fork lift truck. There are some nasty traps nearby. You will have to get rid of them. Start moving towards the traps (#1). Thankfully, they will be destroyed. There's a metal grating here. You will have to raise it by using the fork lift (#2). You may proceed to the next section of this corridor.
You must destroy the second pair of traps. Just as before, this won't be much of a problem. Start moving towards the second wall. Make sure you're moving at a full speed. Thanks to that, you should be able to destroy it (#1). An interactive cut-scene will appear on the screen. Start pushing correct movement keys in order to keep Lara alive (#2). You will find yourself inside a HUGE cavern. As you've probably suspected, you will have to reach the ground floor.
Head on to the stairs located on your left. Start running. You will have to reach a narrow ledge (#1). Be careful! Some of the following moves must be done quickly, mainly because parts of the construction will fall down. Make a jump towards the second ledge. Climb down and turn around QUICKLY. Start running forward. Make a jump towards the nearby stairs (#2). You will only have a few seconds to do that.
Now you will have to reach a nearby horizontal pole. Once you're there, start moving towards the right edge of the screen. The main objective here is to reach a narrow ledge safely (#1). The next jump will require you to reach a second ledge. Start moving towards the right side of the screen. Once again, you'll be in a hurry. Press the F key in order to land on the new platform safely (#2).
You may turn around. Start running towards the end of this ledge. You will have to reach a nearby rope. Once you're on it, turn right. You will have to reach a new platform (#1). I guess I don't have to remind you that the jump must be very precise. Keep moving. Once again, you will have to use a narrow ledge. Start moving right (#2).
You may proceed to the ground floor (#1). There aren't any traps here. You will yourself inside a huge hallway. Start running forward. You should be able to reach large stairs in a few seconds (#2). You will have to head on to the new corridor.
There's only path leading to your current destination, so you can't get lost. Once you've reached a new room, make a jump towards the left stairs (#1). Thanks to that, you will avoid a weird substance. Keep moving forward. You will come across a new corridor (#2). Start off by using the grapple. You will have to pull the metal crate towards Lara. The crate must be placed on the first fiery platform. Climb up and wait for the moment to make both jumps. You should be able to reach the opposite end of this corridor without any major problems.
There's a second trap waiting for you around the corner. Just as before, you will have to use the grapple to pull the crate towards Lara (#1). The crate must be placed on the first fiery platform (#2). Now you will have to make two successful jumps. Once you're there, turn around and pull the crate again. You'll need it in a near future.