Finger on the pulse in emergency repairs to Amsterdam quays and bridges

Amsterdam is at the beginning of an extensive repair operation of many quays and bridges in the old city center. Monitoring the effect of construction work on the environment is essential in this process. Especially if you have to install steel sheet pile walls in the historic canals. For BouwRisk, monitoring the effects of construction work is daily work.

The quays and bridges in Amsterdam's ring of canals are in bad shape. Since the 1980s, systematic cutbacks have been made in the maintenance of this centuries-old infrastructure. The wooden pile foundations are gradually running out of steam. Moreover, the quays and bridges were once designed for use by pedestrians and horse and carriages, not for heavy freight traffic and parking along the waterfront. That is beginning to pay off in many places. Meanwhile, the municipality did take central control from the city districts and established the Quay Walls and Bridges Program. A rehabilitation program is expected to take decades and cost hundreds of millions, if not more than a billion euros. But it must be done: no one wants an inaccessible downtown and unsafe quays. 

Safety Structures

The greatest need must be met first. "The first inventories showed that 190 kilometers of quay are bad, a number of sections are in such a state that a safety construction must be made immediately to prevent collapse," says Yvo Hollman, managing director of BouwRisk, an expertise agency based in Eindhoven that specializes in monitoring environmental influences in construction projects. "A permanent solution requires a long preparation time, but something must be done until that renewal starts to ensure the safety of the quays. Hence, a number of quays will be given a safety structure for the period until renewal. This involves installing a sheet piling at some distance in front of the quay, then filling the gap with sand and stamping the quay against the wall. BouwRisk has been asked to provide monitoring before, during and after the work on quays and adjacent properties in terms of settlement, noise, vibrations and misalignment."

Vibration and pressure

BouwRisk was previously involved in the replacement of a section of quay wall in front of the Anne Frank House and the Westertoren, and in recent months provided monitoring for the construction of the safety structure on the east side of Prinsengracht between Rozengracht and Reestraat. Hollman: "Together with CRUX Engineering BV, where CRUX made predictions of the deformations, noise and vibrations. In addition, CRUX has drawn up a protocol of what needs to be monitored where. Hereby the effects of the work traffic and of the other activities especially the installation of the sheet pile walls are considered. Some of the sheet piles are vibrated in and others are pressed to depth statically. Keeping an eye on the buildings is the most important thing. Two years before the renewal of a quay, we already start measuring the buildings for natural settlement behavior. Unfortunately, this is not always possible when a safety structure is installed. You have to have a good baseline measurement. That's one of the reasons why you can't start working on quays all at once. We mainly monitor quay walls for misalignment. Bad sections can fall a centimeter further out of plumb in just a few months, with a safety construction you stabilize such a development."  

Pulitzer Hotel

In all work, inconvenience is minimized as much as possible. Hollman: "Wherever possible, the sheet piles are vibrated in. At locations where this is not possible due to noise or vibration nuisance, the sheet piles are installed by static pressing (low-vibration). At all locations where sheet piling was installed, we monitored the effects of the vibration. Because of this approach, residents and also guests of the Pulitzer Hotel experienced minimal inconvenience from the work. The sheet piling was installed during the off-season and the canal-side rooms were kept empty during that time. In front of the hotel, a beautiful scaffolding was also constructed on the safety structure. Thus we are all making a virtue of necessity."

BouwRisk, in a combination with RPS and IV-Infra, has several framework contracts running on behalf of the City of Amsterdam to monitor deformations of vulnerable quay walls, it involves dozens of kilometers of quay that are intensively monitored. What will happen to the temporary safety structures has recently become clear. The Municipality issued a pitch for the innovative, rapid approach to the complex quay problems and from this three combinations were selected that have now started the research and development phase to renew quay walls. Pilot projects will start in 2021.