1970s novel about computer hackers extorting a city

Question

I'm trying to find the name of a novel I read in maybe 1975 where an evil hacker was taking control of a city's computers. I think he was doing this to extort money from the city.

The part I remember most clearly is that the hacker demonstrated that he could change the timing of the city's traffic lights. Unfortunately, joy-riders were counting on the timing of the lights when racing down a street. They crashed into a truck and died when the light changed unexpectedly.

Another part was the hacker was about to trip the fire suppression system in the computer center. This would fill the computer room with carbon dioxide and suffocate the operators inside. The operators had a race against time to get out before the system went off. I think the hacker could also lock the doors.

Edit: If I remember correctly, an early sign of the hacking was when people started getting water bills for absurdly high amounts.

I think the novel was science fiction in the sense of how things could be controlled by computers a few years in the future, not speculative. (But it's possible that it wasn't intended as science fiction, in which case I apologize for asking here :-)

I read Crichton's "The Terminal Man" around the same time, so I could be mixing up parts of that book.

Answer 1

Intruder (1979), by Louis Charbonneau.

He’s got the whole town in his hands.

The technical glitches in Hollister, California, began inconspicuously enough—errors in department store billing and production problems at local factories. But the episodes become more malicious when falsified criminal records are strategically released to employers and press, fake medical reports are sent to spouses, and the city’s traffic lights are hacked and thrown into deadly chaos. The only link between these seemingly random occurrences is the Regional Data Center.

Former FBI agent Michael Egan, the RDC’s new security director, knows something more than coincidence is involved in these events. The RDC computers certainly aren’t foolproof, but the incidents of the last week have grown in such frequency and intensity, it can only mean one thing. It’s not a computer malfunction. The system has an intruder.

Someone is in the RDC network, someone who does not belong there. The intruder is cruel, drunk with power, and his games with the RDC have already resulted in a man’s death. If Egan and his colleagues can’t stop him, many more will die. Hollister is under attack, and the only chance for survival may lie within the very machines where the crisis began.

There are some more details in this review on Goodreads.

I read the Readers Digest Condensed Book version from 1979 Vol 125 #4.

Answer 2

Though this was not a hacker, your plot summary otherwise sounds a lot like the 1978 novel Tomorrow City by Monica Hughes. Instead it is a about a computer AI that goes rogue and takes over a city.

A description is out at: Tomorrow City and out at: here

The piece that I remember most was the scene with the joy-riders crashing because the timing of the light was changed. You may also remember a scene where it shuts off heat to residents and some freeze to death.

Good luck.