A NEW BRIDGE OVER DANUBE

Among all the countries crossed by the Danube, Romania has the largest access to this river, fact that represents, on one hand, an advantage, due to the possibilities to turn into good use the whole potential, and on the other hand, a disadvantage, due to its size. The Danube represents an obstacle difficult to cross in the relationships with the neighbor countries, as well as while crossing it on our territory.

The first railway bridges

Since the old times and up to nowadays people have tried to accomplish definite crossings over the Danube, through bridges that provide permanent links between the two banks of the river, no matter in what conditions. The Romans have achieved the first work of this kind in year 105 after Christ, the ruins that remind of its existence being still visible today in the area of Drobeta - Turnu Severin. Later on, in year 1895 there have been inaugurated the bridges for the railways in Fetesti - Cernavoda area. Over 60 years, namely in year 1954, there has been put into operation the Friendship Bridge, between Giurgiu and Ruse, having access on the railways and on the roads. But the necessity to achieve new permanent road crossings, which allow the direct link with Dobrogea and with the Romanian seaside have been solved through the execution of the bridge over the Danube from Giurgiu - Vadu Oii, inaugurated on September 23, 1970.
Economical and social development of Romania, the increase of the exterior trade activity have imposed the achievement of some new bridges with double line railway and road with four traffic lanes in Fetesti - Cernavoda area. It is about a new bridge over Borcea branch, which has been put into operation in 1985, and one over the Danube, inaugurated at the end of the year 1987. Simultaneously, excepting the execution of these bridges there have been also performed works for the road crossing of Ialomita isle in this area. There has been built the highway section Fetesti - Cernavoda, component of the north-south trans - European highway on the territory of our country, on Nadlag -Timisoara - Bucharest - Constanta route.

An adverse state

All the crossings achieved up to present time on the Romanian sector of the Danube are placed in the central area of the river and have solved a great deal the situation of the transit towards Dobrogea. Yet, the problem of certain permanent crossings in the extreme areas - Calarasi, Braila, Galati, Tulcea - have not been solved. In the same time, we have to notice the fact that the crossings on the bridges do not provide the permanent access over the Danube in the area of great urban centers placed on the Romanian bank of the river, according to the demands.
According to the Statistic Bulletin of Romania, 1995 edition, the main towns existing on the bank of the Danube, which are more developed from the economical point of view, had the following number of people: Calarasi - 78,874 inhabitants, Braila - 235,763, Galati - 326,728 and Tulcea - 96,616. The lack of certain direct and permanent accesses from a bank of the Danube to the other has led these urban centers to develop only one bank of the river, on great lengths, with all the implications that result from this process. Similarly, the harbor activity has been extended on great lengths, with limited perspectives of development in the future due to the hydrologic conditions and the reduced possibilities of exploitation.
Currently, the transit from a bank of the Danube to the other is performed only with road and water means of transportation, through those of the two ferryboats. One of them belongs to INF, boat that links Braila and Smardan, providing the continuity of the public operation towards Dobrogea. The other one belongs to the Commercial Company Insula Mare a Brailei and performs the technological and passengers transports necessary for the unfolding of the agro-industrial activities of the Insula Mare a Brailei.
During the wintertime, in the situation in which the Danube freezes, and also during the springtime, when the ice floes flow, and whenever there is fog or storm, the link with Dobrogea practically ceases in Braila - Galati area and also with the entire Moldova. The Danube can only be crossed on Giurgiu - Vadu Oii bridge, fact that increases the distance with 133 km on Tulcea route, respectively with 56 km on Constanta route.
Naturally, such a situation can not last forever. A solution is compulsory!

Are we going to cross the Danube at Braila?

For the achievement of a road and railway link between Braila and Dobrogea, including Insula Mare a Brailei, have been studied, in time, two versions: the permanent connection through the achievement of a bridge and the ferryboat crossing. Pursuant to these studies there has been imposed as optimal solution the building of a bridge, which location has been established at Braila.
At the selection of the optimal locations in order to achieve this important objective - the crossing over the Danube there have been taken into consideration several technical elements. We can mention: the characteristics of the river bed (the width of the water surface at low-water mark and the depth of the river bed at low-water mark), the necessity of the provision of certain navigation clearances (maritime - from 180 x 38 m and river - from 150 x 20 m), the possibility to adjoin to the existing railway and road network and, not at last, the degree of occupation of the area and the correlation with other objectives. Based on these elements, there have been analyzed several locations, the most liked by the District Council being…
.
…E location

This will be situated at the northern extremity of Braila municipal, area where the bed of the river Danube has the width of around 900-m at low-water mark and the depth of almost 25 m. In order to provide the access to Insula Mare a Brailei, in the E location, as well as in other possible, it is necessary to build a bridge over Macin branch, the railway adjoin for the E location being achieved from Baldovinesti station. Being performed an analysis of the traffic conditions on the Danube, there was reached to the conclusion that in this particular case it is necessary the provision of a maritime navigation clearance of 180 x 38 m.
According to the specialists from the Territorial Designing, the building of the railway bridge over the Danube is justified only in the case in which there is achieved a railway connection between Braila, Tulcea and Constanta, through the existing railway section Medgidia - Tulcea.

Studied solutions

A. Bridge over the Danube
Taking into consideration the fact that the width of the Danube at the low-water mark quotation in the area of the chosen location (E) is of almost 900 m, the solutions proposed for the main bridge over the minor river bed have been analyzed in various versions, being accepted the following:
a) combined bridge of railway and road, with the superstructure composed of a beam with continuous iron bars, with the rigidity arch on the main opening, having the openings of 151 m + 300 m + 151 m, extended with two openings each of 151 m, achieving a total length of superstructure of 904 m. The beam with the iron bars has the general orthotropic blading at the inferior flange. The infrastructure of the main bridge is compound of files with massive elevation and the foundations on the mud pilots of large diameter. The inferior quotation of the sole is at the low-water mark quotation (+1.07 NMNS). The railways and the roads are at the same level. The first ones will pursue the route from the inside of the beams with iron bars, and the roads will have the location on the exterior angle of the beams with the iron bars. We have to mention that, according to this first solution, the railways are stipulated with prism of ballast designed to be achieved in a shaft of reinforced concrete that is leaned on the metallic beams.
b) combined bridge of railway and span wired roads, with central opening of 460 m and two marginal openings each of 230 m, resulting a total length of 920 m. The concrete deck is compound of a beam with iron bars through the interior of which the railway will be placed, and through the exterior, on the sole (in the case of the combined bridge), will be placed the road.
c)road bridge, with two or three traffic lanes, in the same version of construction as the combined bridge.

Lengths of bridges and viaducts

Road bridge
- arch solution: L = 960 + 904 + 660 = 2,524 m
- span wired solution: L = 960 + 920 + 660 = 2,540 m
Mixed Bridge
- arch solution:
railways: L = 1,980 + 904 + 1,680 = 3,664 m;
road ways: L = 960 + 904 + 660 = 2,540 m
- span wired solution
railways: L = 1,980 + 920 + 1,680 = 3,680 m;
road ways: L = 960 + 920 + 960 + 2,540 m
Access viaduct on the left bank
- on the railways: 33 x 60 = 1,980 m
- on the road ways: 16 x 60 = 960 m
Access viaducts on the right bank
-on the railways: 28 x 60 = 1,680 m
-on the road ways: 11 x 60 = 660m
With regard to the superstructure of the viaducts we have to mention that, in the case of those of the railways, this is compound of a metallic beam locked with the way on the ballast in the reinforced concrete shaft. At those on the road is compound of metallic beams with "full web", which co-works with the prefabricated slabs made of reinforced concrete.
The viaducts infrastructure, either on the railways or on the road, it is compound of massive abutment and files of the bridge, with the foundation of the drilled mud pilots with 1.08 m diameter, 1.18 m or 1.50 m or on pilots with large diameter made of metallic pipes and prefabricated tubes and of reinforced concrete, introduced though vibration.

B. Bridge over Macin branch
In order to cross the branch Macin, in any of the locations of the bridge over the Danube, there has been stipulated the achievement of a new road bridge or a combined bridge, on the railway and on the road. The main bridge has three widths of 128 m + 160 m +128 m, having a total length of the superstructure of 416 m, which is compound of beams with iron bars on three widths. The infrastructure is compound of massive files with high soles and the foundation on the mud pilots with large diameter.

Bridge versions

Road bridge: L = 6 x 50 + 416 + 6 x 50 = 1,016 m
Mixed bridge, on railways and road
Road ways: L = 6 x 50 + 416 + 6 x 50 = 1,016 m
Railways: L = 12 x 50 + 416 + 12 x 50 = 1,616 m

The necessity and the opportunity to achieve these crossings are demonstrated by the studies of economical efficiency (the internal rate of the liability, RIR, and the economical liability rate, RER, are coping with the accepted limits, over 8%) according to the traffic that will be achieved on Moldova - Dobrogea route.
A key-problem for the transposition in life of the above-mentioned objectives remains the provision of the necessary funds. A welcomed solution would be the attraction of the investments in this area of the country having great possibilities of development in the future due to an extremely favorable geographical position.

Magdalena Bran