milau viaduct

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1.GENERAL INTRODUCTION :

The Millau Bridge or Viaduct as it should technically

be known as provides the final missing link in the A75 auto route ultimately connecting Paris to

Barcelona Prior the viaducts construction traffic would have had to descend the Tarn Valley

causing a bottle neck in the town of Millau especially during the summer months of !uly and

August The multi"span cable stayed bridge passes over the Tarn valley at its lowest point

between two plateaus #n order to do this it had to become the tallest road bridge in the world

creating the world$s tallest bridge piers standing at %&%m' the structure rising to (&(m at the top

of the pylon The bridge also holds the title of the world$s longest multi"span cable stayed bridge

with a total length of %&)*m There is a slight gradient of (+ from ,orth to -outh as well as a

slight curve about a radius of %*'***m The piers are of post tensioned reinforced concrete and

the deck and pylons are of steel

-everal initial proposals were at first considered by -.T/A 0the

1rench 2ighway 3epartment4 in linking the e isting auto routes to the north and south of the

Tarn Valley These included the idea proposed by initially by bridge designer Michel Virlogeu

This included a route that would partially descend the valley' cross the Tarn with a 7**m span

cable stayed bridge and then tunnel through the steeper ,orth side of valley until and 6oining up

with the auto route 2owever this proposal was to prove too e pensive and too damaging on the

local environment #n 88* the decision was made to pass the valley at the bridges current

location with a %5**m bridge Michel Virlogeu proposed a design very similar to the final

structure consisting of seven main piers with approach piers and a slightly different cable

arrangement A change in director at -.T/A saw a controlled design competition take place in

88( to ensure that the best solution was found The only design similar to Virlogeu $s was


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grant of contract was made in May 88: then in !une %*** the contest for the construction

contract was launched' open to four consortia #n March %** .iffage established the

subsidiary Compagnie Efface du Viaduc de Millau (CEVM) and was declared winner of the contest

and awarded the prime contract in August.

In initial studies, four options were examined::

ellow routeBlack route/ed routeBlue route

FIG(1)

https://en.wikipedia.org/wiki/Eiffagehttps://en.wikipedia.org/wiki/Eiffage


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Great Eastern 0 grand Est 4 0 yellow route 4 passing east of Millau and crossing the valleys

of the Tarn and 3ourbie on two very high and long bridges 0spans of :** and '*** m or

%')** and ('(** ft4 whose construction was acknowledged to be problematic This option

would have allowed access to Millau only from the 9arCac plateau' using the long and

tortuous descent from 9a ;avalerie Although this option was shorter and better suited to

through traffic' it did not satisfactorily serve the needs of Millau and its area

% Great Western 0 grand Ouest 4 0black route4 longer than the eastern option by % km

07 5 mi4' following the ;ernon valley Technically easier 0re


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% The low solution' descending into the valley and crossing the river on a %** m 0))* ft4

long bridge' then a viaduct of %'(** m 07'5** ft4 e tended by a tunnel on the 9arCac side

3.CONSTRUCTION :

Two weeks after the laying of the first stone on & 3ecember %** ' the workers started to dig the

deep shafts There were & per pylon 5 m 0&8 ft4 deep and 5 m 0 ) ft4 in diameter' assuring the

stability of the pylons At the bottom of each pylon' a tread of (@5 m 0 *@ ) ft4 in thickness was

installed to reinforce the effect of the deep shafts The %'*** m ( 0%')** cu yd4 of concrete

necessary for the treads was poured at the same time

FIG(2)

#n March %**%' the pylons emerged from the ground The speed of construction then rapidly

increased .very three days' each pylon increased in height by & m 0 ( ft4 This performance was

mainly due to sliding shuttering Thanks to a system of shoe anchorages and fi ed rails in the

heart of the pylons' a new layer of concrete could be poured every %* minutes

https://en.wikipedia.org/wiki/Larzachttps://en.wikipedia.org/wiki/Climbing_formworkhttps://en.wikipedia.org/wiki/Larzachttps://en.wikipedia.org/wiki/Climbing_formwork


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The bridge deck was constructed on land at the ends of the viaduct and rolled lengthwise from

one pylon to the ne t' with eight temporary towers providing additional support The movement

was accomplished by a computer"controlled system of pairs of wedges under the deck the upper

and lower wedges of each pair pointing in opposite directions These were hydraulically

operated' and moved repeatedly in the following se


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Heigh ! "# he $ie%!

P1 P2 P3 P& P' P P

8& 5* m

0( * ft

* 5 in4

%&& 8) m

0:*( ft

: in4

%% *5 m

07%5 ft

( in4

&& % m

0&7( ft

% in4

() &% m

0&&7 ft

7 in4

8& m

0()7 ft

( in4

77 5) m

0%5& ft

) in

TABLE(1)

FIG(3)

A pylon under construction


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The abutments are concrete structures that provide anchorage for the deck to the ground in

the ;ausse du 9aCar and the ;ausse /ouge

3.2 DEC* : The metallic deck' which appears very light despite its total mass of around

()'*** tones 0&*'*** short tons 4' is %'&)* m 0:'*7* ft4 long and (% m 0 *5 ft4 wide #t comprises

eight spans The si central spans measure (&% m 0 ' %% ft4' and the two outer spans are %*&

meters 0))8 ft4 These are composed of 7( central bo beams' the spinal column of the

construction' onto which the lateral floors and the lateral bo beams were welded The central

bo beams have a & m 0 ( ft4 cross"section and a length of 5@%% m 0&8@7% ft4 for a total weight

of 8* metric tons 088 short tons 4 The deck has an inverse Airfoil shape' providing negative lift in

strong wind conditions

3.3 MASTS F

The seven masts' each :7 m 0%:5 ft4 high and weighing around 7** tones 0)8* long tons 77*

short tons4' are set on top of the pylons Between each of them' eleven stays 0metal cables4 are

anchored' providing support for the road deck

3.& STAYS :

.ach mast of the viaduct is e


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water which' in high winds' could cause vibration =dubious – discuss > in the stays and compromise the

stability of the viaduct

The stays were installed by the 1reyssinet company

3.& SURFACE :

To allow for deformations of the metal deck under traffic' a special surface of

modified bitumen was installed by research teams from Appia The surface is somewhat fle ible

to adapt to deformations in the steel deck without cracking' but it must nevertheless have

sufficient strength to withstand motorway conditions 0fatigue' density' te ture' adherence' anti"

rutting etc 4 The Gideal formulaG was found only after two years of research

3.' ELECTRICAL INSTALLATIONS F

The electrical installations of the viaduct are large in proportion to the siCe of the bridge There

are (* km 0 8 mi4 of high"current cables' %* km 0 % mi4 of fiber optics ' * km 0) % mi4 of low"

current cables and (57 telephone sockets allowing maintenance teams to communicate with each

other and with the command post These are situated on the deck' on the pylons and on the masts

The pylons' deck' masts and stays are e


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monitor the reactions of the viaduct to e treme conditions Accelerometers placed strategically

on the deck monitor the oscillations that can affect the metal structure 3isplacements of the deck

on the abutment level are measured to the nearest millimeter The stays are also instrumented'

and their ageing meticulously analyCed Additionally' two pieCoelectric sensors gather traffic

dataF weight of vehicles' average speed' density of the flow of traffic' etc This system can

distinguish between fourteen different types of vehicle

The data is transmitted by an .thernet network to a computer in the #T room at the management

building situated near the toll plaCa

3. TOLL PLA+A:

FIG(&)

The Dare de pHage 0toll plaCa4

The only toll plaCa on the A75 auto route ' the bridge toll booths and the buildings for the

commercial and technical management teams are situated & km 0% 5 mi4 north of the viaduct

0coordinatesF &&I:J( * K, (I J( 8&K.4 The toll plaCa is protected by a canopy in the shape of a

leaf 0formed from ten drilled concrete ' using the crease process4 ;onsisting of 5( elements

https://en.wikipedia.org/wiki/Piezoelectric_sensorshttps://en.wikipedia.org/wiki/Piezoelectric_sensorshttps://en.wikipedia.org/wiki/Ethernethttps://en.wikipedia.org/wiki/Computer_networkhttps://en.wikipedia.org/wiki/Computerhttps://en.wikipedia.org/wiki/Information_technologyhttps://en.wikipedia.org/wiki/Toll_plazahttps://en.wikipedia.org/wiki/Toll_plazahttps://en.wikipedia.org/wiki/Toll_plazahttps://en.wikipedia.org/wiki/A75_autoroutehttps://tools.wmflabs.org/geohack/geohack.php?pagename=Millau_Viaduct&params=44_8_3.01_N_3_1_31.94_E_https://en.wikipedia.org/wiki/Concretehttps://en.wikipedia.org/wiki/Piezoelectric_sensorshttps://en.wikipedia.org/wiki/Ethernethttps://en.wikipedia.org/wiki/Computer_networkhttps://en.wikipedia.org/wiki/Computerhttps://en.wikipedia.org/wiki/Information_technologyhttps://en.wikipedia.org/wiki/Toll_plazahttps://en.wikipedia.org/wiki/Toll_plazahttps://en.wikipedia.org/wiki/A75_autoroutehttps://tools.wmflabs.org/geohack/geohack.php?pagename=Millau_Viaduct&params=44_8_3.01_N_3_1_31.94_E_https://en.wikipedia.org/wiki/Concrete


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0voussoirs 4 the canopy is ** m 0((* ft4 long and %: m 08% ft4 wide #t weighs around

%'5** tones 0%'5** long tons %':** short tons 4

The toll plaCa can accommodate si teen lanes of traffic' eight in each direction At times of

low traffic volume ' the central booth is capable of servicing vehicles in both directions A car

park and viewing station' e


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!une %**)' after 7 months of works The farm and its surroundings can accommodate

entertainment and tourism promotion activities

The cost of this work amounted to L5 : millionF

L& : million of state funds for the realiCation of the area 0access roads' parking' rest area'

toilets' etc

L million for the restoration of the old farm building of Brocue6ouls 0all two tranches4

&.CHALLENGES OF THE PRO-ECT:

?ne of the first challenges to overcome was the need to drill

And bury the foundations of the massive pylons deep into the bed rock The challenge

2ere was that there are cavities throughout the country side that have fractured the

9imestone These cavities are necessary to the survival of the local cheese industry This

Terrain is responsible for containing the bacteria responsible for the blue mold necessary

To make /o


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The wind to cut around the bridge in a smooth manner lowering the chance of twistingDeotechnical engineers had to consider the technical aspects of the route which hadBeen favored to see if it was even feasible The limestone in the area of the Tarn /iver Valley is cracked due to the many tunnels and cavities in the countryside produced by

The cheese industry

The structural engineers found a perfect way to build the piers so that they could Oeep this transparency look and also account for e pansion and contraction of the Bridge deckTransportation engineers had to reveal a plan to get the best way possible for traffic

'.STATISTICS:

%'&)* m 0:'*7 ft4F total length of the roadway

7F number of piers

77 m 0%5( ft4Fheight of Pier 7' the shortest

(&( m 0 ' %5 ft4F height of Pier %' the tallest 0%&5 m :*& ft at the roadwayQs level4

:7 m 0%:5 ft4F height of a mast

5&F number of shrouds

%7* m 0::) ft4F average height of the roadway

& %* m 0 ( ft 8 in4F thickness of the roadway

(% *5 m 0 *5 ft % in4F width of the roadway

:5'*** m ( 0 '*** cu yd4F total volume of concrete used

http://en.wikipedia.org/wiki/Lengthhttp://en.wikipedia.org/wiki/Heighthttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Lengthhttp://en.wikipedia.org/wiki/Heighthttp://en.wikipedia.org/wiki/Volume


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%8*'*** metric tons 0(%*'*** short tons4F total weight of the bridge

*'***@%5'*** vehiclesF estimated daily traffic

L) **@7 5*F typical automobile toll' as of 3ecember %**8

%* km 0 % mi4F horiContal radius of curvature of the road deck

.CONCLUSION:

By using these viaducts we can regulate the traffic problems -o that we can

control the road accidents to a great e tent #ndia is still developing country because of not

having better transportation facilities -o we are being the future civil engineers of the country

we have to design better transportation facilities

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.REFERENCES:

Bridge claims record' -ydney Morning 2erald' -ydney' !anuary %* %-piegel ?nline 0#n Derman4 Q.s ist noch nicht fertigR-akowski' .ric 0%**84 G9ist of 5** 2ighest #nternational BridgesG 2ighestbridges com

/etrieved %* !uly %*G1rom the Millau Viaduct to the PyramidsF Ten of the greatest feats of engineeringG )

?ctober %* * /etrieved %* ("*("*7GThe * greatest engineering feats of the decadeG Construction Week Online % April

%* * /etrieved %* ("*("*7GMillau Viaduct' 1ranceG %**)"*8" ( /etrieved %**:" %"%7The Millau Bridge' page %' BB;

milau viaduct

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