There may be a really low rate off accidental detonation, but you leave mines all over a city for long enough, and some are going to get set off, whether by unexpectedly large vibrations from normal city life or simply by materials corroding after being buried in the sidewalk for a quarter-century. UXO is a big enough problem already. I don’t care how reliable your triggers are, you don’t mine your own cities in peacetime. Or even in wartime, except for times of tactical necessity when the place has already been evacuated.
I totally get this, and wasn't meaning to make light or express ignorance of the serious issues with mines going on in the world today.
Its worth noting that vibrabombs have one huge edge on your typical minefields, in that the triggers are not set for anything that civilians will be doing (stomping about in 12m tall robots), so the UXO problem does go down by an order of magnitude or so vs. our "real world" examples, even if it doesn't go down to zero.
The comparison that came to mind for me was the natural gas piping system built into many cities, including the one I live in. That is a system that laces the entire city with potentially explosive materials that lies just under the surface of the ground. This system requires constant maintenance and repair, needs close monitoring and occasional shutdown altogether around areas of construction, could potentially be hijacked by someone with ill intent (or James Bond), and still randomly explodes once in a while with loss of life and property (we had a school building go up last year a dozen miles from me, luckily it was not in session but there were still fatalities) . . . yet we still keep the system in place because the cost/benefit analysis says we should. Its a great way to heat homes and cook food and provides everyday value.
I doubt 99.something% of Battletech cities would find the cost/benefit analysis in favor of investing in a Vibrabomb network and setting up the further maintenance and support infrastructure needed to keep it functioning and maintained and minimize accidents after it was buried. Unlike natural gas, its not something providing significant daily benefits to their citizen's lives, it is only providing an invasion deterrent.
Imagine, though, a city in the Draconis March in the 3rd SW era where raids can be a yearly occurrence, and you have been brought up from birth to believe those raiders are just itching to finish what Jinjiro Kurita started on Kentares. Imagine a shell-shocked Capellan city just after the 4th SW and under Romano's rule, desperate and fatalistic about your own future and knowing that enemies are coming soon. They might make that call if other options aren't available.
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Let's face it, most of the suggestions in this thread, even the more "sensible" ones that require less investment and danger, are unlikely to be adopted by governments on a budget and building contractors looking to keep their margins. Even swapping out ordinary traffic cameras for the pricier military-grade Recon Cameras would need to be justified in somebody's budget. This is the Battletech universe, though, with constant warfare a reality and crazy economics and occasional command-economy-style decisions being made by House Lords and others not beholden to a voting public. A few of the ideas in this thread could find their way into being in the right places . . . and in isolated instances even some of the more extreme and dangerous options.