The wide angle shot of the cliff and the bridge is a tiny section of the level for starters. This level was in the leaked HL2 but wasnt complete. There is an accompanying screenshot with a closer up view of the buildings on the cliff. What you see in this screenshot, to get to, you drive along a narrow cliff road across the huge level dodging gunfire and rolling mines.

I'll focus on the trainyard though...
The buildings are not flat...look more closely, they have individual balconies with railings, the textures are very high res and very detailed. All the wires and cables...I dont know if these specifically do this, but if you see the game movies and played the leak, many do move if they are interacted with in some way. How about I point out the 3D skybox for distant buildings...Doom 3 doesnt even have this.
The railroad tracks, curve and blend very nicely (thats ALOT of polygons) and it looks to me that there are individual boards in the tracks. Add in the environment shadows...it is very detailed.

Half Life 2 does have Bump Mapping, but it isnt as pronounced or as dependant as Doom 3 is on them. Have you tried turning off Bump Mapping and Specular in Doom 3? The textures are crap, they look like 8bit color mud.