Movable bridges form an essential part of the infrastructure that makes it possible for shipping and road traffic to intersect. They involve a unique interaction between solid mechanical engineering and electrical engineering. The movable parts of a bridge have to satisfy stringent availability, reliability and safety requirements. Movares has experience with both new build and the replacement of existing bridges. Railway bridges are our speciality.
Safety of movable bridges
Movares has extensive experience with the strict European legislation that applies to movable bridges. That legislation uses many ISO and IEC standards that are also recognized in the US. Movares has developed a standard process to assess whether a bridge is safe and to identify the measures required to achieve an acceptable level of safety. The process starts with an inspection of the bridge, and we use a standardized checklist for typical hazards related to movable bridges. Using a risk assessment procedure, we compile a list of safety measures that is then approved by the bridge owner.
In addition to the application of codes and standards we have specific experience in the following areas:
- Responsibility and accountability for the application of safety regulations
- Partly completed machinery
- Modifications to older bridges
- Proof of structural integrity with respect to the safety of machinery (moving parts)
- Functional safety according to IEC 62061
We have provided the following services (amongst others):
- Safety management
- Advice on application of health and safety requirements
- Incorporation of safety regulations in contracts
- Risk assessments
- Reverse engineering for movable parts
- Design of safety measures
- Compilation of technical files
- Quick scans
A selection of our movable bridge projects:
- New Botlek Bridge
- The Nelson Mandela Bridge – the largest movable fibre-reinforced plastic bridge in the world
- Bridge over the River Gouwe
- Ketel Bridge
- Recalculating the Caland Bridge
- Complete design for a movable bridge
New Botlek Bridge
After 62 years’ service, the old Botlek Bridge – an important structure for vehicles using the widened A15 motorway and for shipping on the Oude Maas river – was due for replacement. The bridge forms an intersection between one of the busiest roads and one of the busiest waterways in the Netherlands. In 2015, a new bridge was built alongside – one of the biggest lift bridges in Europe.
The new Botlek Bridge is 14 metres high – 6 metres higher than its predecessor. It has two channels, each 87 m wide, which means that the bridge has to be opened for shipping less often – 20 times a day instead of 50. The bridge carries two lanes in each direction, improving traffic flow on the A15, and the new railway line will allow more freight trains to use the Botlek Bridge. Movares built a special hybrid safety system, to ensure that trains could cross the movable bridge safely. There is a mechanical system (consisting of operating rods) and an optoelectronic version (based on sensors).
The Nelson Mandela Bridge – the largest movable fibre-reinforced plastic bridge in the world
The Nelson Mandela Bridge over the Kolhorn near Alkmaar is the largest movable FRP bridge in the world. This table bridge links the towns of Alkmaar and Heerhugowaard with a busy industrial estate.
The central section, which is made of FRP, is 22.5 m long and can be raised. Because the material used for that section is light, so is the counterweight, which means that less energy is needed to open the bridge. Furthermore, an FRP bridge needs less maintenance and has a longer service life than a concrete or steel bridge. The result is a durable, sustainable structure.
Bridge over the River Gouwe
A set of roads has been built parallel to the A12 motorway to improve traffic flow and safety. The outstanding feature of this new road system is a new movable bridge over the River Gouwe, the Amalia Bridge. Movares designed the steel leaf of the bridge, the operating machinery and the concrete land bridges. The machinery includes two very large trunnion gears, each with a diameter of 4 metres.
- The leaf spans some 30 metres and weighs approximately 1000 tonnes, including the counterweight. This makes the Amalia Bridge one of the largest movable bridges in the Netherlands.
- The bridge is 41 m long in total and 23.5 m wide.
- The bridge has an electro-mechanical drive, which consists of two very large trunnion mechanisms and a single enclosed gear box driven by a 160-kilowatt electric motor.
- The machinery includes a variety of technical features designed to enhance the safety of the bridge and reduce damage in the event of an incident.
- The entire bridge was designed in a single integrated IT environment, with a complete 3D model, using a building information management system.
The parallel road network for the A12 motorway is designed to reduce “weaving” on the A12/A20 interchange by creating a direct connection to bypass it. Weaving is the dangerous situation whereby vehicles leaving the motorway cross those joining it.
The Ketel Bridge is an 800-metre bascule bridge carrying two roads over the Ketelmeer, a stretch of water forming part of the IJsselmeer inland bay. In 2009, the Directorate-General of Public Works and Water Management decided to renew the Ketel Bridge bascules, as they were showing signs of fatigue and the machinery was not up to current standards. Movares supported the process leading to the bridge receiving its CE marking (the certification mark that indicates conformity with health, safety, and environmental protection standards for products sold within the European Economic Area).
The contract did not stipulate the type of machinery that was to be installed, but we chose to use an electromechanical drive operating on the crank/connecting-rod principle. To maximize availability and reliability, a trunnion mechanism was used. The movable bridge consists of two leaves, each with its own drive. The drive system is very reliable, and allows the leaves to be held closed.
Replacing the trunnion gears would be no simple matter, so they and the components directly connected to them are designed for a service life of at least 100 years.
Safety was a high priority, both for road users and shipping once the bridge entered service, and during the construction process. Safety measures included replacing all stairs and railings, fabricating new steel steps, making the supporting pier and inspection gangway accessible and creating escape walkways.
The bridges were floated in via the Prinses Margriet Canal, the lock at Lemmer and the IJsselmeer, and exchanged with the existing bridge leaves. The entire process was carried out in a single night.
Recalculating the Caland Bridge
In 2005 it was decided that the existing Caland Bridge near Rotterdam needed to remain in service – and suitable for heavy traffic – until 2020. Movares carried out various renovation and servicing operations to make this possible.
- Major renovation operations: strengthening the bridge, installing a supporting structure for the overhead line that could move with the bridge and increasing the capacity of the machinery by replacing the drive.
- Servicing: work on the control system to guarantee that the bridge could be used safely.
- Conservation and asphalting work
- Reduction in the time necessary to open and close the bridge
The Caland Bridge was to be modified to reduce noise emissions, which would increase its dead load. The bridge would also be carrying heavier rail traffic, as it was to form part of the Betuweroute freight line linking Rotterdam and the Ruhrgebiet in Germany. Calculations showed that in its existing condition, the bridge could not fulfil all requirements. It was therefore decided to limit the remaining design lifetime of the bridge to 15 years, which would give a safety margin. Accurate calculations of the bridge buckling modes were also carried out. Despite these efforts, it was still necessary to strengthen the bridge, but strengthening was limited to the critical diagonals and connections. Following strengthening, the bridge was fit for service until 2020, when it will be replaced.