The Strait of Messina bridge project

By : Unknown

On : 04:17

In : Mega Structures

The bridge over the Strait of Messina will link the island of Sicily and the Italian mainland.


PROJECT OVERVIEW

This project if completed would stand as one of the Landmark Bridges of the 21st century.  It would be the longest suspension bridge ever built (between towers).

The Strait of Messina (divides the island of Sicily from Calabria in southern Italy) is 2 miles (3km) wide. While the overall length is not a big problem the economics, water depth, wind, and earthquakes all have to be accounted for.

Presently all has been accounted for except the economics.  To avoid the problem of the deep water, the solution was to design the longest suspension bridge ever.  It will have a 3300 m (2 mi) main span and 180 m (590 ft) side spans (overall length 3.7 km (2.5 mi)). The main piers will be founded in 120 m (400 ft) of water. There will be a new patented lighter deck design which deals with aerodynamic and seismic problems. The wind will be no problem as the aerodynamic features of the bridge will allow it to withstand 216 km/hr (134 mi/hr). Earthquakes will have to be huge as the bridge will be able to face without damage a seismic action corresponding to 7.1 magnitudes in Richter scale (severer than the earthquake that destroyed in Messina on 1908). The only obstacle left is the funding.  The bridge is expected to cost five billion dollars and take eleven years to build.

The bridge will be 60 m (196 feet wide) and will have 12 lanes for traffic and two lanes in the middle for trains. This will allow 140,000 vehicles and 200 trains per day. This will cut down transit times of up to 12 hours down to minutes.

The new Messina Straits suspension bridge to link Sicily with the Italian mainland was likely to be one of the most impressive feats of engineering undertaken this century and one of the biggest construction projects ever undertaken in Europe.

Following the plans for the bridge being scrapped by Italy’s new prime minister in October 2006 the project was thought to be totally dead and buried. However, governments change and in April 2008 a general election returned the previous Prime Minister Silvio Berlusconi to power. One of Berlusconi's first acts was to revive the bridge project.

Although the project was welcomed and criticized in equal measure, it is certain that it would have inspired a generation of Italians to marvel at their country's engineering skills and prowess. The bridge would have significantly helped reduce the infrastructural deficit in Southern Italy, creating favorable conditions for the economic growth and social regeneration of the region and promoting an integrated road infrastructure (probably requiring badly needed additional investment).

The bridge was being constructed by the Italian Government, which formed a company, the Stretto di Messina SpA, to oversee construction and operate the bridge when potentially completed in 2012.

Spanning the Messina Straits, the bridge would have been almost 4km (2.5 miles) long and would have cut the two-hour journey time by ferry and train (transporting over 18,000 vehicles per day). The controversial project had been on the drawing board since the 1960s and has been criticized because it would be a waste of public money in Italy where public spending is already overstretched and also because the area in which the construction was taking place had some seismic activity in the past.

The bridge would have cost an estimated €4.4bn ($5.3bn; £3bn) to build. The bridge would have been the world's longest suspension bridge and was expected to have a service life of 200 years.

PROJECT PLANNING

The Strait of Messina Bridge preliminary project is a revised version of the project first proposed in 1992, updated to include the recent findings and resolutions of the Technical and Scientific Committee set up by the Italian Ministry of Infrastructure.

This Committee began work in February 2002, drafting the bridge design guidelines. The Government's technical advisor during the design stage is Steinman International. Stretto di Messina has also made further technical improvements in environmental and urban planning issues.

In May 2006, the bridge building project was questioned by the newly-elected Italian Prime Minister, Romano Prodi, but the project itself could not be scrapped at the time because of agreements and contracts previously entered into by the former government mandating either the construction of the bridge, or an equivalent penalty payment to the contracted construction companies. As will be seen later, he did not give up his questioning.

BRIDGE DESIGN

For the design of a crossing structure, the preliminary project definitively opted for a 3,300m-long single-span suspension bridge that will have the world's longest central span. The deck was to be 3,666m long, including the two suspension side spans, and 60m wide.

The structure was to be composed of three box sections – two lateral ones for the roadway deck and a central one for the railway tracks. The deck's roadway section was to have three 3.75m-wide lanes in each direction (two driving lanes and one emergency lane). The railway section was to have two tracks and two lateral pedestrian sidewalks.

The height of the two towers was set at 382.6m to allow for a navigation clearance with a minimum height of 65m – in the presence of maximum load conditions – and a 600m width; the height of the deck's anchoring on the Sicilian side was lowered by 11m.

The bridge's suspension system was to be secured by two pairs of steel cables, each with a diameter of 1.24m and a total length between the anchor blocks of 5,300m.

The bridge was designed to resist, without damage, an earthquake of 7.1 on the Richter scale – much more severe than that which devastated Messina in 1908. It was also designed to withstand winds of more than 200km/h, given its aerodynamic configuration.

CONNECTION TO ROAD SYSTEM

The preliminary project included 20.3km of road links and 19.8km of railway links to connect the bridge to the existing networks. Under the new design, most of the links were to be developed in tunnels enabling connection of the bridge directly to the new routes.

On the mainland, the bridge was to connect to the new stretch of the Salerno-Reggio Calabria highway (A3) and to the planned Naples-Reggio Calabria high-speed railway line; on the Sicilian side, to the Messina-Catania (A18) and Messina-Palermo (A20) highways as well as the new Messina railway station (to be built by Rete Ferroviaria Italiana).

WIND PROBLEMS

The Strait of Messina Bridge was to be open 365 days a year, 24 hours a day, without any interruption to traffic due to strong winds. This was due to its intrinsic stability and the use of special wind protection barriers that will allow traffic to move normally even in the presence of strong winds.

With regard to stability, the bridge, defined as 'designed by the wind', had a wing profile with aerodynamic characteristics that enabled it to withstand winds at speeds of more than 216km/h (in over 20 years of wind monitoring, speeds of more than 150km/h have never been reached).

Studies in wind tunnels have made it possible to provide a comfortable crossing and optimum stability in the presence of medium / low and strong winds.

SEISMIC ACTIVITY

Suspension bridges are not typically sensitive to earthquakes as the bridge's structural configuration has a type of natural insulation that comes from the typical frequencies of seismic stresses (periods of fractions of seconds). This helps to insulate the structure against the physical possibilities of vibration periods of several seconds and tens of seconds.

The Strait of Messina Bridge was designed to withstand an extreme earthquake with a magnitude of around 7.1 on the Richter scale (the maximum ever recorded in Italy) with the focus at around 15km from the bridge. Such an earthquake is extremely rare.

Key Data:

Start Year	1992 (designs have been on the board since 1960s)
Estimated Investment	€4.4bn
Completion	2012
Start	October 2006; Bridge scrapped by Italian parliamentary vote.
Central Span Length	3,300m
Total Length	3,666m
Suspended Deck Width	60.4m

Cables :

Number of main cables:	4
Diameter of each cable:	4.1 ft (1.24 m)
Length of each cable:	7,650 ft (2,332 m)
Number of wires in each cable:	41,148
Total weight of cables:	166,000 tones

Bridge Specifications:

Tower Height	382.6m, each containing 56,000t of structural steel
Suspension Cables	Two pairs, 5,300m long with a diameter of 1.24m – 44,352 wires for each cable
Minimum Central Navigable Clearance	65m high by 600m wide
Lanes	Six driving lanes, three for each direction (one fast, one normal, one emergency)
Service Lanes	Two
Rail Tracks	Two
Traffic Capacity	6,000 vehicles/hour and 200 trains/day

Key Players:

Sponsor		Stretto di Messina SpA, Italian Government
Main Contractors		Impregilo, Ishikawajima-Harima Heavy Industries of Japan, Sacyr Vallehermoso of Spain and Sacyr S.A., Società Italiana Per Condotte D'Acqua SpA, Cooperativa Muratori & Cementisti-CMC and Parsons Transportation Group
Other Contractors		Systra SA, Bonifica SpA., Systra-Sotecni SpA, Ast Sistemi Srl. Fenice SpA, Agriconsulting, Eurisko, Nautilus, Theolab, Istituto Nazionale della Fauna Selvatica, Marsh SpA and PricewaterhouseCoopers.
Operator		Stretto di Messina SpA

Two satellite pictures of the strait of messina