Art. 241, co. 15-bis, of d.lgs. n. 163/2006, which provides for a shortened time limit of one hundred and eighty days for the challenge of the arbitral award, does not apply to disputes concerning the performance of public service concessions, inasmuch as art. 30 of the same legislative decree excludes service concessions from the scope of application of the public contracts code; the provision establishing the shortened time limit, constituting a derogation from the general regime governing the challenge of the arbitral award under art. 828 cod. proc. civ., is to be strictly construed and cannot be extended beyond the cases expressly provided for.