The Netherlands built a 72-metre bicycle roundabout above a busy junction; 24 steel cables suspend the circular bridge from a 70-metre pylon | World News

Representative Image of a circular bridge resembling a flying saucer, suspended above traffic, with cyclists and pedestrians crossing above ( AI Generrated Image)

At a busy junction in Eindhoven, the Netherlands, cyclists ride around a circular bridge suspended above motor traffic. Known as the Hovenring, the structure resembles a flying saucer held aloft by a tall, cigar-shaped steel pylon. Its circular deck has a diameter of 72 metres and is suspended from the central pylon by 24 steel cables. Cars and other motor vehicles pass through the junction below, while cyclists and pedestrians cross above. Designed by Dutch engineering firm ipv Delft, the bridge became a local landmark for its distinctive form and lighting. Its first period of use was cut short in January 2012, when cable vibrations led to the cycle roundabout being closed. Following repairs and adjustments, it was officially opened to the public on 29 June 2012. The designer lists the construction cost at €6.3 million. Its unusual appearance rests on an engineered system of cables, a circular counterweight and a tall central pylon.

Hovenring Eindhoven: why the city built a circular cycle bridge above a busy junction

The Hovenring was developed to address congestion at a junction connecting Eindhoven with Veldhoven and Meerhoven. In an interview published by ipv Delft, senior designer and project leader Adriaan Kok explained that the existing ground-level roundabout carried different types of traffic and was poorly designed for cyclists. The development of a nearby housing estate added to the need to redesign the intersection to accommodate growing traffic. Eindhoven wanted an alternative to cyclist underpasses and a conventional roundabout at road level. The city asked ipv Delft to explore possible designs, and the team developed an elevated circular roundabout with four connecting bridges. The arrangement allows cyclists and pedestrians to cross above the road while motor vehicles continue underneath. Kok also identified the junction’s connections towards Eindhoven Airport and the A2 motorway as part of its wider transport context.The design reflected Eindhoven’s association with lighting and technology. Known as the City of Light because of its historical links with Philips, Eindhoven wanted an innovative structure that used lighting creatively and complemented the nearby Evoluon, a futuristic, saucer-shaped building. The circular bridge offered a way to combine the city’s visual ambitions with a practical transport solution. Space was a major constraint. To create comfortable gradients for the approach ramps without substantially expanding the junction’s footprint, the road level underneath the bridge was lowered by approximately 1.5 metres. The ramp gradients range from 2% to just over 3%, according to ipv Delft. Kok also described how the designers addressed local concerns about the slopes: stakeholders were invited to cycle over other ramps around Eindhoven whose gradients had been measured in advance, without being told the figures beforehand. The exercise allowed participants to judge the slopes for themselves.

How 24 steel cables and a concrete counterweight support the Hovenring

The bridge’s structural design centres on a circular deck, a single pylon and 24 steel cables. Rather than attaching the cables to the outer edge of the deck, the designers connected them to its inner side. According to ipv Delft’s project description, this arrangement helps prevent twisting, or torsion, in the deck. In his interview with ipv Delft, Kok explained that the inner circular counterweight is partly filled with concrete and helps balance the deck around the cable attachment points. The cable placement and counterweight work together to support the circular structure. M-shaped supports near the approach spans provide additional stability.The circular deck has a diameter of 72 metres, according to ipv Delft. The designer’s specifications list a width of 5 metres. The central pylon rises 70 metres above the ground. According to steel fabricator Kersten Group, the pylon is made from 23 conical steel segments, with plate thicknesses ranging from 20 to 50 millimetres. Kersten also describes slotted holes cut into the inside of the pylon where the cables come together. The designers wanted a thin circular deck and a powerfully shaped pylon. In its project description, ipv Delft explains that a standard cable-attachment arrangement would have created a bulky concentration of steel near the top of the pylon, so the team developed a tailor-made solution. Positioning the pylon in the middle of a busy road junction also required approval from Eindhoven’s traffic planner.

Hovenring lighting and cable vibrations: the challenges behind the landmark

Lighting is central to the Hovenring’s appearance after dark. The space between the circular deck and the inner counterweight contains aluminium lamellas, translucent sheeting and tubular lights, creating a visible ring of light. LED lighting integrated into the railing illuminates the bridge deck, helping users recognise one another’s faces. Additional lights attached to the cable framework and counterweight illuminate the junction below, according to ipv Delft. Cable vibrations interrupted the Hovenring’s early use. In January 2012, Dutch regional broadcaster Omroep Brabant reported that the junction had been closed after wind-driven vibrations raised concerns about the cables’ condition. Engineers investigated the problem before the cycle roundabout could open officially.A 2013 study by T. Argentini, L. Rosa and A. Zasso, titled Experimental Evaluation of Hovenring Bridge Stay-cable Vibration, was published in WIT Transactions on Modelling and Simulation, volume 55. The researchers identified vortex shedding as the cause of the vibrations. This phenomenon occurs when wind flowing around a cable produces alternating vortices that can make it vibrate. The paper also examined the effectiveness of a Stockbridge-type damper and assessed the fatigue life of the bridge’s stay cables.In an April 2012 report, Omroep Brabant said damage to the cable anchorages had become known in February and that all the anchor rods had since been replaced. Remaining work included painting and lighting, with rain delaying the final coat of paint. The bridge’s reopening preparations also involved measures to control cable vibrations. In an interview published by ipv Delft, Kok said the team had set aside a budget for vibration-control measures and ultimately spent less than the amount allocated. The solution included two types of dampers designed to address different vibration frequencies.The repairs did not proceed entirely smoothly. Omroep Brabant’s coverage of the opening reported that a mounting error had left dampers improperly fitted, prompting another closure shortly before the official ceremony. The Hovenring was officially opened on 29 June 2012. The episode illustrates the engineering challenges behind a structure whose striking appearance depends on a carefully balanced system of cables, a central pylon and a circular deck.