THE WORLD’S TALLEST BRIDGE

This is the Bridge Which Faced Some Great Engineering Problems From The Start Of The

Project

•This bridge was to be constructed over one of the deepest valley of France, which had two major

engineering threats for the bridge.

1. Foundation Problems Caused By The Porous Lime Stone

2. Major And Frequent Land Slides

So why construct a bridge with such threats in the first place?

Because Of This

• A75 is the motorway that connects Paris to Spain. The motorway goes right to the southern France where it meets with one of the deepest valley of the France.

• A dead end.

• So, from here all the traffic was diverted to the small town of Millau which caused a great problem for the residents of the town.

• And after years of suffering to the locals finally the French government decided to make a bridge over the valley.

•So the project was out.

•The worlds tallest bridge, 2.5 km long was constructed.

•A great engineering achievement.

•Millau Viaduct.

IMAGINE BUILDING A SERIES OF EFFIEL TOWER ,AND THEN LYING A FOUR LANE HIGHWAY ON IT . ACROSS

ONE OF THE DEEPEST VALLEY IN THE FRANCE.

The Millau Viaduct is a cable-stayed bridge that spans the valley of the River Tarn near Millau in southern France .It is the 12th highest bridge deck in the world. Millau Viaduct is part of the A75-A71 auto route axis from Paris to Montpellier

FOUNDERS of Millau Viaduct

Dimensions of the viaduct

Length : 2,460 mHighest pier : 245 m (P2 )Height of metallic pylons : 90 mSlightly curved : constant radius 20KM

THREE DUANTING CHALLENGES THEY FACED

1) BUILD THE TALLEST BRIDGE PIERS IN THE WORLD

2) PUT 36000TON FREEWAY ON TOP OF IT

3) ERECT 7 STEEL PYLONS HUNDREDS OF METER ABOVE THE SOLID GROUND

Construction Overview

• Temporary piers used to help launch and support the deck as the the pylons were constructed.

• The 2460m deck was launched in two pieces.

• Pylons and cables were added on top of the piers.

THE PIERS

Top view of the P2 pier close to

its full height

The crane is linked to the pier and

raised in the same step

Each PIER is supported by four deep shafts, 15 m (49 ft) deep and 5 m (16 ft) in diameter.

EACH PIER WAS COSNTRUCTED AT THE SECTIONS OF 4 METER

• AFTER THE CONSTRUCTION OF THAT SECTIONS THE MOULDS ARE REMOVED

• THE CYCLE IS REPEATED EVERY 3 DAYS FOR CALIBRATING THE MOULDS FOR NEW SECTION

• THE MOULD IS NEEDED TO CHANGED AS THE PIERS HAVE DIFFERENT CROSS SECTION THROUGH IT’S LENGTH

• THE VARITION IN CROSS SECTION OF THE PIER IS SHOWN

• THE TOTAL HEIGHT OF PILLERS COMBINED IS MORE THEN 1 KM , SO THE MOULDS NEEDED TO BE RECALIBRATED OVER 250 TIMES

THE PROGRESS OF PIERS WAS MONITERED BT GPSPIER 2 WAS NEEDED EXATLY TO BE AT

245 m from ground546 m from south

1916 m from north

Completion of Pier Construction.•Months after months the piers grew taller and in November 2003 their construction was finished.

•Amazingly each pier was perfectly on its place, dead on target.

Construction Innovation:The Millau Viaduct Deck

Launch

STEEL DECKS

• THEY OPTED FOR STEEL DECK OVER THE CONVENTIONAL CONCRETE BLOCK , AS IT’S NOT ECONOMICAL AND SAFE TO LIFT CONCRETE OVER SUCH HEIGHTS

• FABRICATION OF THE DECK SECTION WAS DONE ON STEEL FACTORY

• AROUND 2200 SECTIONS EACH WEIGHING UPTO 90 TONS AND SOME WERE 22M LONG

TO OVER COME THE DIFICULTY TO SLIDE THE DECK OVER THE SPAN OF 342M

• THE INTRODUCED STEEL TEMPORARY TOWERS BTWEEN TWO PILLERS BEACUSE THE SPAN BETWEEN TWO PIERS WAS LARGE AND DECK COULD NOT SUPPORT ITSELF

• FIRST TWO PYLONS AND CABLES ON BOTH THE END WHERE ON THE SOLID GROUND BEFORE SLIDING IT , TO GIVE THE DECK AN ADDITIONAL STIFFNESS

Deck Launching

• 7 temporary piers help support the weight of the deck , as the longest the deck could support was half of the span

• 2 deck segments were launched from the each end of the bridge.

Hydraulic Launchers

• Computerized launchers push the pre-fabricated deck segments onto the piers.

• Each cycle moves the deck 600mm. Total of 5000 cycles required.

• THE CYCLE IS REPEATED EVERY 4 MINUTES

Nose Recovery

• Weight of steel box-girder deck sags as span is completed.

• Nose recovery system attached to raise the deck to the level of the next pier.

• This aligns the deck for the level and curvature of the next pier

Completion of deck

• Two deck segments joined in May of 2004.

Pylon Construction

•After the deck construction was finished it was time to erect the pylons to provide cable support for the bridge.

•The temporary piers were supporting the deck but due to the flexibility of the steel the deck was very undulating, the deformations were quite large.

•So the 90 m tall and 700 tonpylons were installed as fast as possible.

Egyptian Technique

• Pylons and cables were needed to straighten the undulated deck.

• For placing the pylons steel engineer Marc Buonomo used a technique which was practiced in the ancient Egypt.

•In this Egyptian method the pylons were lifted slowly using a hydraulic crane.

•As they were being lifted they were also made to pivot by two temporary steel towers, both of them secured by a cable.

•As the bridge is lifted it also pivots until it is vertical and the it’s erected.

Attachment Of Cables

•With all seven pylons in place it was time to attach the cable stays that would straighten the rippling deck and give it the strength to endure the traffic load.

•The roadway weighs over 40,000 tons and the 154 cable stays should prevent it from sagging or collapsing.

•These cable stays are made of 91 individual steel strands and have breaking strength of 25,000 tons.

•These stays are strong enough to hold 25 jumbo jets all at full throttle!

A Great Challenge Faced By Millau Viaduct

An issue that presented itself after the bridge was completed was the fact that the wind speed at the level of the bridge was “up to 151 km/hr,” which is significantly more than the wind speed that would be found at ground level. This would cause

serious issues driving on the bridge because the high wind speeds would push vehicles to the side, making driving dangerous. This problem was addressed by the inclusion of wind screens that reduce the affect of the “wind by 50%,” effectively

causing wind speeds on the bridge to reflect those on the ground.

The Wind Screens

Used to reduce the speed of wind by 50%

•Intriguingly the Millau Viaduct is not straight. As a straight road could induce a sensation of floating for drivers, which a slight curve remedies. The curve is constant circular curve of 20km radius.

•Moreover the road has a slight incline of 3% to improve the visibility.