PSI - Issue 84

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 84 (2026) 1247–1254

© 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference Abstract The detailed safety evaluation (VAL4) was introduced by the Italian Ministerial Decree 247/2022, "Guidelines for risk classification, safety assessment, and monitoring of existing tunnels," and it is required depending on the result of the preliminary safety evaluation VAL3. The VAL4 evaluation is intended to provide a comprehensive assessment of the safety level of the tunnels with respect to the risk classes introduced by the Guidelines. Since the Guidelines provide only general criteria for performing the verifications, this paper proposes a structured methodological procedure for conducting the VAL4 evaluation, in compliance with those criteria. The methodology presented herein also establishes general criteria for determining potential extension of the service life of the interventions present within the tunnels. The first part of the paper examines the methodological workflow for the VAL4 evaluation, addressing both the assessment of knowledge levels and the structural verification procedures, for which a distinction is drawn between inspection sections with and without existing interventions. The second part of the paper introduces a dedicated methodology for assessing possible extensions of the service life of existing interventions, applicable both to inspection sections requiring VAL4 and to those not subject to detailed safety verification. III Fabre Conference: Existing Bridges, Viaducts, and Tunnels: Research, Innovation, and Applications A methodological framework for the execution of the detailed safety evaluation VAL4 for existing tunnels and for the evaluation of existing interventions service life extension in compliance with the Italian Guidelines for risk classification, safety assessment, and monitoring of existing tunnels I. Vangelisti a, *, W. Salvatore b , F. Morelli b , D. Peila c , A. Carigi c , G. Bordi d , V. Farmeschi d , V. Prisco d , C. Bonaldi e a Consorzio FABRE, Consorzio di ricerca per la valutazione e il monitoraggio di ponti viadotti e altre strutture, Largo Lucio Lazzarino 1 – Pisa, 56122, Italy b Università di Pisa, Lungarno Pacinotti 43 – Pisa, 56126, Italy c Politecnico di Torino, Corso Duca degli Abruzzi 24 – Torino, 10129, Italy d SINA S.p.A, Viale Isonzo 14/1 – Milano, 20135, Italy e Autostrada dei Fiori S.p.A. - Via della Repubblica, 46 - 18100 Imperia

* Corresponding author. E-mail address: iacopo.vangelisti@gmail.com

2452-3216 © 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference 10.1016/j.prostr.2026.07.035