Peace Bridge brings together two historically separate communities in Derry, Northern Ireland. The construction project combined challenging design, fabricating 65-ton units in Rowecord’s works, and transporting these from South Wales to Northern Ireland. BIM helped project team from design to transportation and erection. The accuracy of the model and the control over the geometry during fabrication and erection were major contributors to the success of the Peace Bridge project.
Peace Bridge’s S-shape brought challenges to design and construction process as there were lots of curved, complex shapes. Rowecord tackled the challenge by modeling curved plates as a series of triangles and unfolded using the macro within Tekla Structures. The workflow was important for the success of the project: The detailers methodically worked from one end of the bridge to the other to ensure the overall geometry, including the pre-cambers, was correct.
From model to workshop
During the project the Tekla model worked as the source of general arrangement and fabrication drawings. As Rowecord wanted to save time in the workshop, they decided to export information from Tekla to enable fabrication staff to scribe the positions of the stiffeners onto box girder plates. Although this cost time in the drawing office, it made assembly in the workshop considerably easier and saved time during fabrication.
“Although it is difficult to quantify, creating the model in Tekla environment reduced errors which was a significant benefit. Being able to see that everything fits together is a real advantage,” says Jeremy Masters, Drawing Office Manager of Rowecord.
Collaborating, checking and surveying with the model
Tekla model helped the engineers to develop details as they could see what the other project members were doing. Also the architect used the Tekla model, without problems, to detail the aluminum flooring panels. Naturally the model proved useful for showing the project parties how the bridge was going to look like when finished.
With the building information model, checking the Peace Bridge’s fabrication drawings was easier: The consulting engineer viewed the model and saw exactly how his drawings had been interpreted. Elsewhere other project members could check the engineer’s setting out relatively easily. The team managed to avoid clashes during the design phase as they were easily spotted already within the model.
Surveyors utilized the model to check and record relevant points along the structure. Due to the complicated geometry of the Peace Bridge, it would have been difficult and time consuming to produce all drawings for fully checking the setting of the bridge. With building information model, Rowecord’s surveyors could quickly and easily pick on the points they wanted.
The Peace Bridge’s box section and cantilever arms of the main deck were fabricated in 32-meter long sections, weighing approximately 65 tons each, in controlled indoor conditions at Rowecord’s works in South Wales. The builders fitted even lighting and cables before erection. Rowecord utilized the model to develop the temporary works, and to calculate weights and centers of gravity for transportation, lifting and erection of the bridge.
Transporting a bridge calls for some arrangements: Peace Bridge traveled ca. 480 kilometers (300 miles) by road and ca. 170 (100 miles) by sea - the deck sections were the largest ever taken on the ferry. Rowecord surveyed the road route from South Wales to Northern Ireland to identify any street furniture that needed removing
Modeling with Tekla for temporary supports and transportation
As the Peace Bridge was largely build off-site, Rowecord had to consider the use of temporary steelwork and include it to the model already in the design and detailing phase.
“We exported a 3D dwg file from the model to set up the trial erection,” tells Drawing Office Manager Jeremy Masters. In the works, they temporarily propped the bridge decks into position and trial assembled the adjacent section to ensure site fit-up. In addition to fit-up, the project team had to plan the transportation of the bridge.
“We set each bridge section onto the trailers we used for transportation in the model, and we also modeled temporary props and support beams that stabilized the massive load for the entire journey,” Masters says.
For erecting the bridge, the construction team calculated centers of gravity and checked dimensions with the model.
“Using the Tekla model for calculating centers of gravity and checking weights is straight forward and reasonably quick,” Jeremy Masters tells and continues: “It is essential for large, irregular loads like parts of Peace Bridge to know exactly the weight and where the center of gravity is. Then temporary lifting attachments can be designed to ensure that the loads can be transported and lifted safely.“