Tunnels are still OP

[paule3000]

I employ similar strategies as recommended by others (Trixi, 5hifty, Castaway, Pogmothoin etc.) above and I also find tunneling not that much of a problem. I find tunnels all the time, but I always find them in time. Doing a shakedown every couple of days does wonders, doesn't upset prisoners much (I think it should do more) and needs virtually no micromanagement. I always do them at night, when most guards have spare time. Didn't have an escape for hundreds of ingame days.
(All my maxsecs have access to the workshop btw.)

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Have approx 22 tiles (or more) from any cell toilet to the exterior wall
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Why 22?

[xander]

Why 22?

Presumably because the time in which it takes a prisoner (or group of prisoners) to tunnel 22 tiles is more than the time between searches in the original commenter's usual style of play.

xander

[Axe22]

Prisoners will prefer to sleep rather than tunnel if they are tired, and they only tunnel at night. So if you cut down their sleep time they will become tired at the end of the day and therefore will sleep rather than tunnel...even if they possess the pickaxe tool.

Also keep in mind that time is greatly accelerated in PA. A prisoner with a year long sentence will serve that time in way less than 365 in-game days. Thus, each day really represents much more time than just a single day. So this means that one single night of tunneling represents like maybe two or three weeks of effort (if not more). They also tunnel much faster when they reach the big pipes. So keep the fat pipes to the interior of the prison as much as is practicable.