REHABILITATION OF THE OLD BRIDGE

MOSTAR

NEWSLETTER    5                      NOVEMBER 30, 2002         MOSTAR, BOSNIA AND HERZEGOVINA

 

Works on the bridge are at full power

 

PAVEMENT DISMANTLING FROM THE BRIDGE REMNANTS

 

Pavement dismantling on the right side of the Bridge began 31.10.2002. As you were informed in the last Newsletter, each pavement stone has been previously marked, documented and measured. This is a very delicate job, because the emphasis was put on the fact that the largest possible number of these stones is to be returned on its original place. The workers have carefully, with hand tools, separated stone by stone, liberating it from mortar, silicon and soil. 

 

Pavement dismantling from the Bridge

 

Pavement was then piled on wooden surface into truck, and then driven to Harem Semovac. It was sorted there, additionally cleaned and put in previously prepared shapes. 

Wooden shapes are made according to real dimensions and form of paving on the Bridge. Nylon basis were then placed on their bottom and on top of them 10cm thick layer of sand. 

 

Pavement piled on Harem Semovac

 

 

ARCHEOLOGICAL EXCAVATIONS

 

Archeological excavations began after pavement dismantling. They are conducted in a way that surface layer of soil is removed, while the whole surface is brought to certain level.   

 

Quadrant on the right bank

 

On the right bank quadrant is dug in the dam. Until now we have reached a depth of apx. 2.5 m below the surface of pavement. Remnants of three walls were found, and they were examined, documented and has digging continued. Dam that is dug out is removed by crane.

 

Left side is explored only to a depth of 0.8m, because here excavations are conducted in more difficult conditions and on incomparable larger surface. Digging is done in soil, between very weak walls, so great attention is given also to the safety of workers. Remnants of 2 pavement layers were found here by excavations, on upstream side, in northern profile of quadrant, directly by the edge of previous pavement of the Bridge. First layer was found on a depth of 0.3m, with dimensions 3.5m x 2.9m, and below that the second one, on 0.5m, 3.4m long and 2.3m wide.

 

Quadrant on the left bank

 

FINDINGS OF PREVIOUS ARCHEOLOGICAL EXCAVATIONS

 

After conducted extended but still unfinished research works and with analysis of archive documents, development of the location can be divided into several developing stages:

 

-around year 1444 towers on both sides of Neretva exist. On the right bank self-standing semicircular tower Helebija, on the left semicircular tower Tara with six-cornered fortification.

 

-before 1452 first wooden bridge was built which connected the fortresses. The bridge was wooden with two console distinctive parts and middle one which was “hanging”. Semicircular, unsymmetrical annex of fortification was built for bridge reliance on the left bank, and on the right bank trapezoid enlargement of plateau of Helebija tower with abutments of the bridge.

 

 

REMNANTS OF WOODEN PLUMBING

 

On the left bank, right next to north-east part of the quadrant, wooden plumbing pipe was discovered with outer diameter 24cm and inner one 12cm. The pipe was covered with 5cm thick layer of red dirt in order to make it water-proof.   

 

16th century plumbing pipe

 

OUTLET OF RADOBOLJA TO NERETVA

 

This year we are witnesses of extreme high water levels of Neretva and Radobolja. High-capacity outlet of Radobolja to Neretva was built to allow undisturbed flow of works in those conditions

 

Elements foreseen by the project were prepared and concreted on harem Semovac, and then 16th and 17th of November concreting of outlet itself was executed.

 

Beside outlet itself, communication over it was arranged. The road was widened and turning point for pickup trucks was made.

 

Concrete outlet

 

DISMANTLING OF REMNANTS OF PARAPET AND CORNICE FROM THE LEFT SIDE OF THE BRIDGE

 

19th of November dismantling of bridge remnants began on the left bank of Neretva. This job is very risky because console of the bridge which remained after its demolition, is in very ban condition. Fractures in construction are visible. The fact that solid support for auxiliary construction still does not exist under his part of the bridge, makes the job even harder.

 

First, pavement and the layer of red dirt under it were removed from the console. After that, parapet was liberated which broke in two parts during demolition of the bridge. A tape was dragged through beneath one part of the parapet and without any further damages crane carried it to the platform with other blocks of the bridge.

 

 

PREPARATIONS FOR ERECTING THE CENTRING

 

 

One of the most important elements which will influence the reconstruction of Old bridge certainly is the centring. In the last Newsletter we presented its construction and the main principles. In this one we are already in a position to inform you that preparatory works for its erection are at full power.

 

Drilling of holes for anchors

 

1.        CONCRETING THE FOUNDATIONS

 

First in a row of preparatory works is concreting the foundations for heavy scaffolding.

 

The works have begun on the right bank of Neretva, by nailing down iron anchors 2m of length into rocks under the bridge. Anchors are nailed down into rocks 90cm and covered with Altex.

 

Concreting of scaffold foundations

 

Wooden bedding was erected on the rock around the anchor and concreting the layer of liable concrete was executed.

 

After that, additional bedding for the foundation foot was erected on the existing one, and reinforcement was placed inside and concreting was done again.

 

 

This kind of basis does not guarantee that pavement will be conserved in the best possible way.

 

During pavement dismantling on the left bank we found cavity directly under the upper layer of pavement. Cavity was formed during recent archeological excavations, because the layer of already washed and no quality soil - simply licked out through the cavities in the walls. System of supporting columns and beams was made even then, so the stability of pavement was ensured at least for some time. 

 

It was necessary to approach this problem very carefully because all structures of old walls and pavement had been disturbed. Also, all dismantling work needed to be planed and done step by step, because all of these elements were interacted and only joined together gave relative stability of the whole structure.

 

 

Removal of pavement on the left side of the Bridge

 

It is interesting that under pavement on left side of the Bridge we found remnants of installation – probably Austria Hungarian. That was plumbing gander pipe 20cm diameter.  

 

 

REMOVAL OF CONCRETE BLOCKS

 

Removal of concrete blocks on both sides of the Bridge was done from 1-16. November.

 

 

Removal of concrete blocks

 

Total five blocks were broken. Three on right and two on left side of the Bridge. Great attention was given to minimal damage of the surrounding pavement and also that surrounding structure is not disturbed.

 

 

-between 1452 and 1566 on the right bank tower Helebija was reinforced by sub-wall with round corridor and the crown. Tower was elevated with wooden crown. In the same period Tara was elevated, building which served  for accommodation of the crew was built within the fortification. Year 1522 mesdzid of Sultan Selim was constructed, smaller mosque for the crew of the fortress. South-west corner of fortress was fortified, tower Hercegusa was constructed.

 

-1566 construction of builder Harjudins` bridge was finished. Distinctive flanking abutment walls were built which reduced the span of the bridge and one-arched stone bridge was built. Over the new entrance-gate into fortress wooden watchman tower – “cardak” was built. Such a Tower also existed also over the gate of fortification on the left bank.

 

- between 1566 and 1690, the fortification side walls were strengthened by erecting an inner, parallel and distanced wall and filling the space between the two walls with soil. The Tara Tower was risen once again, with a new, stone, merlon on the top. The Halebija was also risen, with new merlin and gun holes. Between 1680 and 1695, Captain Halebija, after who the tower was named, rebuilt it into a covered blockhouse. He rose it and opened a number of windows, turning its uppermost floors into the crew dwellings.

 

Archeological excavations 2000. – dowels of chane bridge

 

- between 1690 and 1878, lesser rebuildings were made on facades, with no significant new building. Between 1714 and 1716, lower floors of the Halebija Tower were turned into a jail. At upper floors, the facades were modified by opening of new windows. The watchmen corridor on the jacket wall was risen as a ramp to the northern gate. The new parapet was built at the same time.

 

-  buildings of the end of the 19th ct. and the 20th ct. The fish-market building at the right bank. At the left bank, next to the bridge, a smaller storehouse. The Mesdjid was built again on the old foundations. Between the Mesdjid and the Tara Tower, a new residential-office building was built.

 

 

Archeological excavations 2000. –feet of pillars

 

Crane is lifting a piece of parapet

 

The same thing was repeated with the rest of the parapets, cornice beneath it and stone blocks.

 

 

REPAIR OF ABUTMENT WALLS

 

To begin with the grouting of abutment walls – first important thing is to replace those stone blocks which are destroyed or damaged. Only solid and unique wall can receive grouting mass without any problems.

 

Testing of conglomerate with ultrasound

 

Conglomerate blocks from Bisce polje quarry are being subjected to the list of tests, which are necessary for determining their quality and compactness.

 

 

LIME

 

22nd of November 10 tons of lime arrived on auxiliary site on harem Semovac. Lime was burned and extinguished in natural manner and it is at least 12 months old.

 

Storing of lime on harem Semovac

 

 

2.        PLACING THE PONTOON

 

Anchor block on the right bank

 

In order to allow undisturbed communication of people and material during erecting of centring, it is decided that Neretva is to be temporarily spanned with pontoon.

 

Excavation, drilling and covering the anchors were done beneath feet of temporary walking bridge. After that, planking and steel elements were erected and anchor blocks concreted.

 

Placing the first pontoon element

 

Three iron ropes with diameter 15.2mm were erected and dragged through beneath the two anchor blocks on the right and left bank. Separate ropes of pontoon elements were hooked on the main rope with slip-knots, which allow adjusting the position of pontoon to various water levels.

 

Four pontoon elements are connected with steel latticed porters over which the deck for communication is placed.

 

Setting pontoon connection

This NEWSLETTER was made in accordance with prevailing articles of the Contract No 002/2002 about the Rehabilitation of the Old Bridge, by ER-BU CONSTRUCTION / TURKEY