How can I make the Barrens dangerous again?, Without resorting to random encounters... Options

[jklst14]

I am currently running an SR4 campaign which has been going great. In developing the setting (the game is based in Philadelphia), I've emphasized how dangerous the Barrens are, especially the Z zones and the players have understood and respected this.

Now over the course of the last year, the characters have ventured to the Barrens multiple times - to confront a gang, find a enemy's secret hide out, destroy a secret drug lab etc... I still talk about how destitute and dangerous the Barrens are but with all this going back and forth, they no longer really feel that deadly.

I know this is my fault. So what I would like to do is introduce an element of danger. I want the characters to really and truly hesitate before venturing into the worst of neighborhoods. The characters, while competent, are not big or scary. So I feel like it should be risky for them. But I would ideally like to do this without resorting to random encounters (i.e. "Okay, 3d6 gangers show up and attack you at random) which could just bog down the game with non-plot related combat.

Any suggestions on what I can do?