Hairline cracks in the steel. In October 2016 the girders of the bridge over the river Merwede at Gorinchem were found to be unsafe for heavy vehicles. As soon as the discovery was made the Dutch department of Public Works closed the 1961 bridge to buses and HGVs to avoid overloading the steel. A team of 12 operating companies was charged with reopening the bridge to heavy vehicles as soon as possible.
A week and a half. Whereas tender and preparation processes normally take at least a year, the plan for repairing the bridge was ready in no time. “Everyone sensed the urgency,” recalls Pjotr Mak, manager for rail, road and water at VolkerRail who was closely involved during the initial weeks of the project. “In the morning I phoned my colleague who works for the Volkerinfra team responsible for maintaining the waterways in the province of Zuid-Holland to offer my help. Two hours later I was sitting at a table holding emergency talks with the department of Public Works.” In collaboration with the client’s own engineering firm the team went in search of a suitable solution that was also practical from a technical point of view. Could the bolts we had chosen be supplied immediately? How heavy were the proposed steel reinforcement plates? Feasibility and viability were therefore major prerequisites for the plan.
Stress, tension and safety
Despite the time pressure, safety remained the unquestionable priority for the duration of the project. “We collaborated intensively with the safety experts from the start,” says Pjotr. “In a calamity project you need extra focus on the safety culture. Everyone is hugely driven so you have to protect people from themselves.” Sessions were therefore organised to teach contractors to recognise signs of stress and tension in their co-workers. A close eye was also kept on how many hours colleagues had worked. Given all the exhaust fumes air-quality monitoring also helped increase safety, as did extra assistance to road traffic and shipping. The measures proved effective. Pjotr: “We completed the work with minimal incidents for our employees. I’m really proud of that!”
Life-size model of worksite
Repairs to the bridge’s support beams proved exceptionally challenging. The access hatches to the box girders were small: round holes with a diameter of just 60 cm. This made it difficult to take along the steel plates. In addition the toxic substance chromium-6 was found to be present. In order to carry out the repair as safely and effectively as possible a life-size reconstruction of part of the box girder was made, not only to practice the repair but also to test the psychological component. “We wanted to be sure that we were deploying engineers who were comfortable working in a tight, confined space,” explains Pjotr.
Quality in a QR code
The right people, tools, preservation and layer thickness. “The repairs had to be demonstrably executed in accordance with the design,” says Pjotr. And so the team used the quality system developed for the Galecopper Bridge, which involves using QR codes to link physical areas of the bridge to a specific work process. What steps have been performed? When? And by which engineer? The department of Public Works was also given access to the system, which enabled the quality control to take place simultaneously with the works. Pjotr: “An hour after the last bolt had been tightened the first lorry was driving over the bridge.”
The VolkerWessels team
“Repairing the Merwede Bridge was a real team effort. That’s what I find really cool about projects like this. With more than 12 VolkerWessels companies involved, everyone contributed their expertise in order to achieve the common goal. It’s brilliant to see what we are able to do when we work together.”
-Pjotr Mak, manager for rail, road and water at VolkerRail