After the cutscene with DJ Bobby Ricks in the radio tower, exit the broadcasting booth through the other door. Go down the corridor, there is a pile of rags/trash that appears to be interactable. You need to set that pile on fire, so that you can trigger the emergency systems and escape. For that, you need some sort of accelerant, such as a Diluent. If your puzzle level is easy or normal, Go to room 1703 and get the Diluent from the workbench. There is also a first aid kit nearby. If your puzzle level is hard, go all the way down to the kitchen and find the diluent there.

You get:

Diluent
Highly Flammable Liquid

It is time now to ignite a fire. Go back to the pile of junk and use the Diluent on it. Then use the lighter. The fire alarm will sound. Doors around you start shutting down. Otherworld sequence begins.

Silent Hill: Downpour Otherworld Void Chasing You

Start running away from the Otherworld. Make sure to knock over the cages on the way. Use the valve to get the door open. Take a left in the junction. Fall down a hole, a door closes behind you and you find yourself in a small room with a mirror. There is a sign on the wall that says:

In case of power malfunction, use Manual Override

Turn the switch under the sign (this switch is invisible on normal and hard levels but you can still turn it). Run through the door that just opened and into the corridor. Otherworld keeps chasing you. Go down the corridor again and turn close the door with the manual override valve. One entry closes, and another one opens. Run through the open section, keep knocking down cages behind you. You will see some truck remains, indicating that you are in the garage. You will reach a gate that's closed. Turn left.  Keep running past some cars that will fall down from the ceiling. Follow an upside down sign that says "Exit".  The Otherworld will slowly be draining your health, so be sure to use a first aid kit if you are running low.

Go past a valve, and then find an electric switch soonafter. Flip the switch, and enter the next area. When you enter the office, the whole screen turns upside down. Go back through the door. Go towards the green blinking light.  Enter some cage, and it will start descending, and then moving horizontally. You will see a wheelchair rolling  in front of you, before the cage turns right. You will see another cage with someone else, and then many more cages filled with people. Looks like this represents a prison.

When the cage ride is finally over, some water will rain on you and the cage goes to an abrupt stop. As you leave the room, the Otherworld void starts chasing you again. Run towards a big Exit sign, following what looks to be an executioner, or the Boogie Man..  You fall down, run through the corridor, grabbing the first aid kit on the wall in the next room.  Go into another creepy hallway, the infirmary corridor.  The corpses on the wall are splashing blood - run past them.

Reach a big metal door with a switch near it. Pull the switch. Run through the next area, avoiding falling cages and  the holes created by them. There is a first aid kit in one of the side rooms. Be ready to fight a screamer that emerges from behind one of the cells.

When you clear the chamber with the cages, you will reach another corridor, with a portrait. Rotate the portrait to unlock the next zone. Run fast through the area with the spinning spike wheels. You will find yourself in the clock tower. There is a button on the platform. The clock's hour dial is rotating. Press the button to start and stop it.

Answer to Giant Clock Dials Puzzle

Silent Hill: Downpour Clock Tower Dials Puzzle

You have to press the button at the right moment, so that the moving clock dial stops exactly at the platform on which you are standing, creating some sort of bridge. Press the button a few times to get a sense of timing. There is a delay from the moment you press the button, and until it stops. The harder the puzzle difficulty level, the longer the delay will be. This might take you a few tries. Walk on the giant hours dial to the center, then proceed to the giant minutes dial. It will start spinning. Balance yourself as you walk towards the edge of the moving dial. Proceed to the platform and through another narrow corridor, then down some stairs.

You now reach some bladed gears traps. Make sure to go through them carefully. If a gear hits you, you will take a significant hit to your health. If you are under 50% health it is recommended you use a health kit now. The higher the difficulty level, the faster the gears will be spinning. Try going through the gear JUST as the blade passes the ground. When you reach the big metallic gear that stops every couple of seconds, cross it as soon as the blade is stopped.

There are some shotgun shells and Pistol bullets after the gears. Pick them up, then go up through some more stairs. There will be another trap in front of you. Two giant blades are swinging right and left at a very fast speed. Step on the pressure plate in front of you to slow them down, then run through them when they are the furthest away from the center. Climb up a bridge. You will arrive at some stair. There is a wheelchair at the top. As you climb the stairs, they transform into a slide and you slip down. Navigate yourself through the traps and other obstacles.

Silent Hill Downpour Falling from the Clock

The scene ends with you hanging from a giant clock, and then you fall down - a deep plunge...