Tram Rail

Tram Rail is the 24th level of Quake 4. It also is the only Quake 4 level in which the player is using a Strogg vehicle.

After having turned the Tram and repaired the track at the Tram Hub Station, Cpl. Kane and Cpl. Cortez now take the Strogg Tram to reach the Data Processing Terminal. On their way, they are attacked both by Strogg aircraft as well as Tactical Strogg in other Trams. However, Kane manages to defeat all enemies and the two Marines arrive unscathed at the Data Processing Tower to processing another objective.

Hot on the Hardline
This is by far the easiest vehicle level of Quake 4: Cortez drives the Tram while you have control of the Tram's Machine Gun. Your only objective is staying alive by eliminating the pursuing Strogg Trams and the Fighters, similar to the early convoy missions. On lower difficulties, you can ignore the latter completely as they deal very little damage to your Tram. What you should really concentrate on are the enemy Trams. While they cannot use their built-in gun against you as it faces backwards, every Tram has one Tactical Strogg with a Railgun or Hyperblaster on it. Your Tram's shields are weaker than you think and they totally lack an armor plating, so open fire on each Tram as soon as it appears. The railgun could be a real threat to your tram, if you watch the railgun being fired, elimate the source immediately. Alternatively, you can try just to kill the Tacticals, but that's very difficult as their Trams are constantly moving and the offer very small attack surface, but they are easier to kill. If you take heavy damage at the beginning, don't give up. Like all tech your tram will be repaired if left undamaged for some time. Your machine gun has unlimited ammo and it will not overheat, use this to your advantage and just keep shooting - the easiest way to bring down the other trams is to shoot at the supports they hang from, this takes down the tram and Tactical Strogg in one go, letting you concentrate on the aircraft, which on higher difficulty are what does the real damage.

After a few minutes with Cortez occasionally yelling at you, you reach the Data Processing Tower and the level will be over.

Trivia
The tram rail map is in fact twice as long as it appears in the game, if you leave the car with the 'noclip' cheat (you have to let it crash to get out), you can follow it back for miles, however riding the trams is tricky, as the character is no longer anchored and you tend to get thrown out on sharp curves.