Technical and economic feasibility of phase 1 (DocFAP) S.S.115 "Southwestern Sicily."
Route: Gela – Agrigento – Castelvetrano. Macro-lot 1 from the A29 Castelvetrano junction to the Sciacca Ovest junction (inclusive).

Project overview

The project concerns a variant to State Road 115 "Sud Occidentale Sicula" in the section affecting the municipalities of Castelvetrano, Menfi, Sciacca, and Sambuca di Sicilia, the first in the province of Trapani and the others all in the province of Agrigento. State Road 115 "Sud Occidentale Sicula" is a fundamental part of the regional road network, as it is the only expressway along the southern coast of Sicily, from Castelvetrano to Gela.

The modernization of the SS 115 Gela–Agrigento–Castelvetrano route has been a primary objective for years in order to complete the Sicilian road and highway network.

The long stretch between Gela and Castelvetrano, as well as the complexity of the project due to the presence of several towns currently crossed by existing roads, led ANAS to divide the entire section into nine functional macro-lots and subsequently to begin feasibility studies for those defined as priorities. These include the present Macro Lot 1, which consists of the project from the A29 Castelvetrano junction to the Sciacca Ovest junction (inclusive), for a total length of approximately 23 km.

For the section under consideration, three route alternatives were evaluated in addition to alternative 0: 1, 2A, and 2B. Alternatives 2A and 2B both involve upgrading the current S.S.115 South-West Sicilian road with a left-hand doubling, with only the replacement of the decks for the existing viaducts in 2A, while 2B involves lowering the levels by 15 m at three viaducts. Alternative 1, on the other hand, involves the construction of a northern bypass to the current S.S.115.

All solutions involve the construction of major engineering structures (viaducts and tunnels) and minor structures (underpasses and overpasses), as well as the adaptation and construction of junctions to ensure connections with the main road network.

Based on the alternatives identified, a transport analysis was carried out to define the expected traffic flows on the new foothill axis and a Cost-Benefit Analysis (CBA) was performed to compare the cost/opportunity associated with the implementation of one design alternative compared to the others, comparing the economic feasibility indicators of the various alternatives considered.

A multi-criteria analysis was performed to compare the various project alternatives based on an overall assessment of their sustainability from a technical, environmental, economic, and social point of view.

The project was subject to public debate, a process aimed at involving stakeholders in a public project which, due to its physical size and cost, has an environmental and social impact on the local area.