Hey, I think I know that guy. Good at tennis, terrible mapper
Seriously though, I would simply build a new map from scratch since that whole map is basically a semi circle (canal) surrounded by a bunch of hollow cubes (buildings) with the doors and windows punched out so players can enter the buildings.
The most complex part, aside from the trolley, is the bridge which is basically 3 hollow cylinders placed together, cut off the bottom, intersect it and stretch it out to the desired size.
You could pretty much rebuild the whole thing in about 30 minutes.
That was my second or third map I made back in 2001.
The idea was to make a red light district and see if it was possible to have female bots (hot babes) in the windows.
IIRC everything worked except the bots would be invisible in online games only. Something about bots standing behind a transparent brush in Unreal-1 online mode.