I guess this movie is from the end of the 80s. I remember the plot hours like this: an stereotypical suit and tie man is in a big city. It gets too late fit him and the city start to get dangerous. I think he escapes from something and get s into the sewer tunnel and tubes of the city. There he is being followed by a gang members who try to kill him. At the end he prevails by killing the last big bad guy with a piece of pipe which he stabs in the bar guy chest. The movie finished when the protagonist finally can go up to surface level and it is day again and the city has the everyday look of a normal busy morning.

I watch this on TV. And I have googled and googled without success for years.