If an eligible bridge is owned or maintained by more than one municipality, the municipalities owning or maintaining such eligible bridge may enter into an interlocal agreement concerning such eligible bridge. Such interlocal agreement may provide, among other things, that one municipality shall be responsible for undertaking and completing an eligible bridge project, maintaining such eligible bridge project, applying for a grant for such eligible bridge project and the apportionment of costs for such eligible bridge project. A municipality is authorized to enter into such an interlocal agreement by vote of its legislative body and the provisions of sections 7-339a to 7-339l, inclusive, shall not be applicable to such interlocal agreement. Any such interlocal agreement entered into prior to May 27, 1987, is validated.