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Description of Construction


Spans


Contrary to the fully closed construction of the Stephenson’s bridge, Lentze designer spans with parallel truss walls. Such spans turned out not only lighter and more economical, but also less exposed to the pressure of the wind. The spread of each of them was the same and equaled 130.88 metres in the axes of the pillars, 128.60 between the supports and 121 metres in the light of the openings. The spans of the bridge have dense pattern of truss girders with poles and cross-bracings made of flat bars. The upper and the lower strips create open chamber profiles consisting of angle bars and plates connected with rivets. The height of the girders equals 8.68 metres and their reciprocal distance – 6.43 metres. Both main girders link from below the truss crossheads, which carry the weight of the road with its working load. Strengthening of the construction of the span is provided by three horizontal bars, one on the lower and two on the upper level. The road surface was made of wooden joists and planks. The space between the girders of the bridge made it possible to lay only one track in the axis of the bridge. On its sides there were two lanes for road traffic. As the width of the bridge was very limited the road traffic had to be stopped for arriving trains. Pedestrians were given footpaths 0.94 metres in width on both sides of the truss walls of the bridge.


The Bridgeheads and the Gates

The monumental character of the bridge was stressed by the bridgeheads made of bricks, with massive entrance portals with rectangular towers taller by 12.5 metres than the girders. Inside here were casemates and rooms for guards. On the portals two reliefs 7 x 4 metres in size were placed. On the western portal – a relief by Gustav Blaser from 1860 with a fictitious scene of the bridge being opened by Frederic William IV, The inscription read: “Under the rule of Frederic William IV, begun on 27th of 1851 and opened for the traffic on 12th of October 1857”. The relief on the eastern portal designed by the sculptor Hermann Schievelbein in 1859, showed medieval Lithuanians tamed and converted by the Great Master of the Teutonic Order – Winrich von Kniprode. The description underneath read: “To commemorate the greatest rise of the Teutonic Order in Prussia under the rule of the Great Master Winrich von Kniprode”. Both reliefs were removed in 1929 by Polish authorities.


The Turrets


The pillars of the bridge were crowned with ten turrets (two on each pillar) in the neo-gothic style referring to the architecture of the castle in Malbork. The role of the turrets is not only limited to their decorative function; They prevented the spans from transversal movements. Only four turrets have managed to survive until now, two were destroyed in the detonation in 1939 and the following four were pulled down in 1948.


Characteristics of the present construction of the bridge


The present construction of the bridge consists of 12 spans of various types.


1. Span 1 is a simply supported beam construction built in 1961. The spread of the span equals 18.50 metres, the width of the road surface 8.90m, the bearing construction of the span consists of 4 steel girders with a cooperating reinforced concrete plate of the platform.

2. Spans 2 and 3 are the construction of an English military bridge of ESTB type with a driving surface at the bottom; previously the spans were parts of the railway bridge. The main girders are bolted trusses of parallel strips of X type. The platform is made of steel cross-ties and spars, on which prefabricated reinforced concrete plates were laid. The spread of the spans is 125.27 and 126.79m, the continuity area being 1.905m in length. The width of the road surface is only 3.50m, the width of the footpath is 1.20m. In 1998 limited tests of steel from ESTB spans were carried out. On the basis of endurance and chemical tests it was ascertained that the samples were of open-poured, carbon-including, constructional steel of ordinary quality.

3. Spans 4,5 and 6 are the original construction of Lentze, made of multiple truss. Spans 4 and 5 make a continuity, span 6 has only a bearer left after the destroyed old span 7. The upper and the lower strips of the girders make open chamber profiles consisting of vertical and horizontal brasses linked by means of angle sections and rivets. The space between the strips is a web of crossing flat bars of changing distance (more dense at the supports), additionally supported by vertical steel elements. The main girders are linked below with truss cross-ties, on which the construction of the wooden platform is laid. In the level of lower strips there is a horizontal truss wind bracing of X type. The upper bracing of girders is made of frames consisting of elements of the truss, vertical truss membranes and two horizontal wind bracings of X type. In 1997 at the Universität Kaiserslautern and in Schweißtechnische Lehr - und Versuchsanstalt Saarbrucken, detailed mechanical and chemical tests were carried out on samples taken from the bearer of span 6. The chemical and endurance tests showed the steel has stratified structure of varied endurance characteristics in the perpendicular and parallel direction (compared to the direction of rolling).

4. Spans 7 -9 are simply supported trusses with driving surface on the top, constructed in years 1946 – 1947. The main girders are riveted trusses of parallel strips with W type trussing, the spread of spans being 3 x 39.50 m. On the strips of upper truss and on the middle spar supported on vertical truss concentration there is a wooden road surface. The width of the road is 5.30 m., the width of the footpath is 0.90 m.

5. Spans 10 – 12 dating back to 1912 are simply supported riveted trusses of parallel stripes with driving surface on the bottom. The spread of the spans is 3 x 81.60 metres. On the surface of lower truss strips there is a platform consisting of riveted cross-ties and spars made of rolled double-tee iron. Shapers of “Zores” type are laid on the road; the width of the road being 6.05m, the width of the footpaths – 1.40 metres.