Blocked account/bank guarantee as security for the municipality

Transfer to the municipality! The costs are higher there. And there are no interest payments anyway. From the banks' point of view, I can understand it. Too complicated and expensive. Not proportional.

And then? That has to be booked in the municipal budget, and the titles for "temporary custody of amounts" with earmarked spending restrictions, but repayment possibility, are probably rather scarce there.

Was subordinate land charge not accepted?

Subordinate would have been possible up to iirc 70% of the house and land costs, we were above that. And then the bank said they would rather go fully subordinate than split it. Fine by me, it wouldn't have changed anything, only the registration would have become more expensive (the mortgage was already in place and didn't have to be touched).

And then? That must be recorded in the municipal budget somewhere, and the titles for "temporary safekeeping of amounts" with earmarked spending restrictions but repayment possibility are likely to be rather scarce.

Your problem? Asking doesn't cost anything and a good solution

if the street is damaged at all, then by the contractor who is doing the shell construction. What if he provides a bank guarantee or through an extended insurance (car or liability)

Escrow account at a law firm or [Notoaranderkonto]? Unfortunately, it also incurs fees, but it should serve the purpose well.

A bank guarantee costs significant interest. The municipality is to create a usage contract with you, transfer the duty of traffic safety, and transfer the additional maintenance effort to you, period.