荷兰埃因霍温市的Heerbaan和Meerenakkerweg路口上悬浮着一座“飞碟”式桥梁，这就是世界上首座环形自行车专用天桥。荷兰是世界著名的自行车城市，除了民众自觉骑自行车是对自然环境爱护的体现外，政府与民间对单车客的支持与配合亦不在话下，为让民众能安全无碍的骑车穿越繁忙的公路，ipv Delft在Eindhoven的一条高速公路上兴建了一座供自行车骑乘的高架桥Hovenring，它的功用不只在平日的交通运输，也是假日民众骑车休憩的去处，而整座具有设计感的建筑在落成后，更成为当地新地标。这座自行车天桥每天帮助超过5000名自行车骑车人安全通过有2.5万辆汽车行驶的交通要道。
这里曾经是一个平交路口，随着附近的发展，人流车流的不断激增，政府不得不邀请荷兰桥梁专家ipv Delft提出解决方案。圆形斜拉桥似乎是最好的选择。整座环岛桥包括一个70米的中央塔、24条钢缆、和约1000吨钢材制作的桥面，24条钢缆均匀的连接到圆桥内侧、与地面的M形支架一道确保着桥梁的安全稳定。
Like a flying saucer, the steel bridge hoovers above the Heerbaan/Meerenakkerweg intersection, its impressive pylon marking the entrance way to the cities of Eindhoven and Veldhoven. There used to be a level crossing here, but the development of a nearby housing estate meant the intersection needed changing in order to cope with growing traffic. As Eindhoven City Council refrains from cyclist underpasses and didn’t want a level crossing roundabout either, they asked Dutch bridge specialist ipv Delft to look at possible solutions. A circular cable-stayed bridge soon appeared to be the best option.
Structure
The bridge comprises a 70-metre high pylon, 24 steel cables and a circular bridge deck and is made out of circa 1.000 tons of steel. The cables are attached to the inner side of the bridge deck, right where the bridge deck connects to the circular, concrete counter weight. This way, torsion within the 72-metre diameter bridge deck is prevented.To ensure stability, concrete was added to sections of the bridge deck as well. The M-shaped supports near the approach spans also ensure stability.Soon after the pylon was put in place, the cables started vibrating visibly.
Vibrations like these (caused by the wind) are nearly impossible to predict. After extensive research by structural experts, two types of dampers (high frequency and low frequency) were attached to the cables, solving the vibration issues.
One of the challenges of the design process was the spacial integration. The existing infrastructure and buildings set the boundaries for the grades of the slopes leading up to the roundabout. As space was limited, it was decided to lower the ground level of the intersection underneath by a metre and a half, allowing for a comfortable slope for pedestrians and cyclists.
TAILOR-MADE
The design and building process offered many technical challenges as well. Ipv Delft had a very clear view of what the bridge should look like: little more than a thin circular bridge deck and a powerfully shaped pylon. Amongst other things, this meant the standard way of attaching cables to the pylon wouldn’t suffice, as it would result in a bulk of steal near the pylon top. Therefore, a tailor-made solution was designed. The same applies to the M-shaped supports near the span bridges.
Lighting design
Befitting Eindhoven’s identity as the ‘City of Light’ (Eindhoven is home to the Philips company), ipv Delft also made a lighting design for the Hovenring. One of its main elements is integrated into the circular deck. The space in between counter weight and deck has been fitted with aluminum lamellas, translucent sheeting and tube lighting, which results in a clearly visible ring of light at night. Together with the illuminated pylon, the ring of light ensures the bridge’s spectacular appearance at night.
The functional lighting is integrated into the railing, where LED-lighting illuminates the bridge deck and ensures facial recognition of the bridge users at the same time. Lights attached to a cable framework in between pylon and bridge deck and to the inner surface of the circular counterweight illuminate the intersection underneath.Both day and night, the pylon bridge is a true eye-catcher, spectacular in its simplicity.
在我们国家，骑自行车上班的人少得可怜，周末的时候稀稀疏疏的可以看到几个自行车爱好者，骑着越野自行车在宽大的机动车马路上挤。在我们拥挤的城市里，骑自行车似乎成为了一件奢侈的运动项目。荷兰国还有专属的自行车道路，甚至还有专属的自行车环岛高架桥，道路照明设计不比机动车道路的差。上班的时候骑着自行车，告别拥挤的公交，空闲的夜晚，也可以牵着爱骑来到这里欣赏城市夜景灯光设计，虽然能够听到桥底下传来的汽车引擎做声，但是这里是属于自行车的。
In the summer of 2012, design office IPV Delft realized one of its most talked about cycle bridges to date: The Hovenring in the Dutch city of Eindhoven. The cable-stayed bridge offers cyclists and pedestrians an exciting crossover. With its impressive 70-metre pylon, 72 meter diameter, thin deck and conspicuous lighting, the cyclist roundabout is a new landmark for the city. Like a flying saucer, the steel bridge hoovers above the Heerbaan/Meerenakkerweg intersection, its impressive pylon marking the entrance way to the cities of Eindhoven and Veldhoven.
号外：位于上海陆家嘴的环形人行天桥 Circular Pedestrian Bridge in Lujiazui, China
