Manko Z.
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SCAFFOLDS FAILURES CAUSED BY VEHICLE STRIKES DURING 1
CONSTRUCTION OF NEW VIADUCT OVER A-18 MOTORWAY IN POLAND 2
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Zbigniew “Zee” Manko 7
Professor of Civil and Structural Engineering, Bridge Division, Institute of Civil Engineering 8
Wroclaw University of Technology, Wybrzeze Wyspianskiego No. 27, 50-370 Wroclaw, Poland 9
Tel./fax (+48) 71 352-92-74 zbigniew.manko@wp.pl 10
(Corresponding author) 11
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Word count: text (3122) + 7 figures (7 × 250 = 1750) + 0 tables (0 × 250 = 0) = 4872 15
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Submission date: June 5, 2009. 17
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TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.
Manko Z.
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Abstract: The paper is presented cases of failures of steel scaffolds damaged by vehicle strikes 1
during the construction of new viaducts over the upgraded A-18 motorway in Poland. After 2
several vehicle strikes into the scaffold structures their damaged components were no longer 3
serviceable (considering the safety of the construction works being carried out). This put the 4
contractor to additional expenses connected with the replacement of the damaged scaffold. The 5
causes and consequences of the failures are given and the necessary solutions adopted in the 6
considered cases – whereby the traffic situation significantly improved – are described. 7
Moreover, it is proposed to increase the minimum vertical clearance required during the building 8
or repairs of bridge structures. 9
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Keywords: Scaffold Failure, Vehicle Strike, Damaged component, New Object, Viaduct 12
Construction, Motorway A-18. 13
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TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.
Manko Z.
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INTRODUCTION 1
Formerly in Poland, a little attention was paid to the bridge-specific design and erection of 2
scaffolds, which was the cause of many serious failures (1), (2), (3), (4), (5), (6), (7), (8). Today 3
bridge scaffolds are classified as engineering structures and require the detailed design, including 4
all aspects, which may occur from their erection, through the full loading of the spans during 5
concreting, to their dismantling, in accordance with the current guidelines (PN-M-47900-3 (9), 6
PN-M-47900-1 (10), and PN-M-48090 (11). When new bridge structures are built over transport 7
obstacles, the continuity of vehicle traffic must be ensured, particularly on national roads, which 8
carry traffic through the whole bridge construction period (12), (13), (14). 9
Unfortunately, the heavy trucks (e.g. TIR lorries) and tractor-trailer units carrying various 10
machines and equipment drive through the clearance gates shaped in the scaffolds using during 11
building of motorway bridge structures most often strike at the new scaffold components already 12
built. It refers these both as well as the trucks of permissible and over normative dimensions 13
which mainly conducting to serious damages of scaffolds or their structural elements. 14
Using as example motorway viaducts WD-14 and WD-12 built over national road A-18 15
(which is being upgraded), the failures of the scaffolds erected to build on site the concrete 16
objects are described and their causes are explained. The cases considered here and the ones 17
presented previously (1), (2), (7), (13), (14), (15), (16) clearly show the need to modify and 18
update the guidelines for erecting scaffolds for the building of road bridge structures. This 19
applies particularly to the minimum headroom (vertical clearance) since the current standard one 20
is inadequate. The above considerations should be taken into account in the designs of bridge 21
structures. 22
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DESCRIPTION OF OLD AND NEW VIADUCT WD-14 24
The old reinforced concrete viaduct (built in 1934) consisted of two spans having an effective 25
length l
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= 14.00 + 14.00 = 28.00 m. The span overall width was 6.76 m, load class D (200 kN) 26
according to the PN-85/S-10030 (17), the vertical clearance – 4.53 m. The viaduct was situated 27
at a skew of 45 to the road’s longitudinal axis. Because of the viaduct’s bad technical condition, 28
it was not worthwhile to upgrade it and so it was demolished (Figure 1). 29
The new viaduct is located at the 0+179.79 km of Cisowa – Jedrzychowiczki (Henrykow) 30
local road No. 4918009 being upgraded. The viaduct makes possible the safe crossing of national 31
road No. 18 at its 13+634.37 km. The designed viaduct WD-14 is located in the place of the old 32
demolished one (Figure 1). 33
The new reinforced concrete viaduct with a trapezoidal single-girder cross section and a 34
continuous-beam static scheme has four spans with an effective length l
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= 18.00 + 27.00 + 27.00 35
+ 18.00 = 90.00 m. The axes of the supports are parallel to the national road and with the 36
viaduct’s longitudinal axis form an angle of 44.99’. The middle spans cross the two carriageways 37
of the national road. There are technological strips and the local road embankment slopes under 38
the extreme spans. The main girder is 1.50 m high and 2.70 m and 3.20 m wide respectively at 39
the bottom and top (at the level of the cantilevers’ bottom). The cantilevers’ width varies from 40
0.21 to 0.40 m and their outreach is 1.90 m. The overall width of the load-carrying structure is 41
7.00 m. The overall width of the viaduct is B = 7.70 m, including the roadway between the curbs 42
(6.10 m) and sidewalks with the rigid barriers (2 × 0.80 m). The viaduct’s total surface area 43
bounded by the deck edges is A = 7.70 × 92.10 = 709.17 m
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. The local road’s technical class is L 44
(4), (5). The target traffic clearance under the viaduct is H
c
= 4.70 m. The viaduct traffic loading 45
is as for class B (400 kN) according to the Polish Bridge Load Standard PN-85/S-10030 (17). 46
TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.TRB 2010 Annual Meeting CD-ROM Original paper submittal - not revised by author.
