Travel through catacomb subrails is a mission in Jak 3. Pecker said that Onin said Jak needed to come back to Haven City, as the catacombs are "the key to the planet's very survival".
Completion of this mission in the PlayStation 3, PlayStation Vita, and PlayStation 4 versions of Jak 3 will unlock the bronze trophy Railing at the Wind.
Walkthrough[]
You'll be racing at break-neck speed using a Catacombs rail rider (fires with 
) through the catacomb subrails, which is mostly a long tunnel filled with a lot of defensive systems. For starters, there's a couple gaps here and there which you want to avoid. The various cones, pillars and other obstacles won't instantly kill you, but they are still harmful to your vehicle. You can also drive on the top side of the tunnel and actually go in circles the whole ride, though it is not recommended. Spamming the fire button does help clear the path.
The most dangerous are the red drones that fly in front of you and will kill you in one shot. The other most dangerous section is the bit where you fly through open air with only a number of devices to keep you on track (apparently). However, the moment you took the wrong angle here to even make a slight change in your direction, you are bound to head of the mark and pretty likely to crash into something instead of landing safely.