Articulated buses are a common sight in Europe. Bi-articulated buses are far less so - but Utrecht is one of several places I have found them operating.
Operation of Utrecht's city bus services has recently changed hands. From December 2013, the concession to operate them is held by QBuzz (trading as U-OV, website in Dutch only). Prior to that, Utrecht's bus services had been operated by GVU (Gemeente Vervoerbedrijf Utrecht) and its parent company, Connexxion.
I visted Utrecht briefly in June 2013. This post reflects what I found then, a few months prior to the change of operator.
Utrecht is home to a large university, to the east of the city. GVU's bi-articulated buses were operating on two routes linking the university with the central railway station. These routes were running at very high frequency, up to every 3-4 minutes, carrying large numbers of people.
With the service running that frequently, and with such high-capacity vehicles, you might think the service would be better provided by tram or metro rather than buses. If so, you wouldn't be alone.
Utrecht already has a small light rail system, opened in 1983, which starts from Utrecht's central railway station and heads into the south-western suburbs.
The system is being extended across the city to the university, with the extension due to open in 2018.
As well as the bi-articulated vehicles, there were plenty of articulated buses in use on Utrecht's streets.
While GVU operated the routes to the inner parts of Utrecht, services to the more outlying parts of the city were operated by Connexxion.
Both operators were also using standard single-deck buses on a number of their routes...
... while GVU were operating smaller vehicles such as this one on route 2, serving Utrecht's museum quarter.
Route 2 had been used to trial an electric bus in 2010. On taking up the concession for Utrecht's buses in December 2013, U-OV introduced three new electric buses on route 2. The new buses are charged wirelessly whilst at their terminus outside Utrecht's main railway station.
Connexxion's buses on local routes in Utrecht carried a yellow and brown colour scheme. These weren't the only Connexxion buses in Utrecht.
Connexxion also operated services from neighbouring towns. They continue to operate these, details can be found (in Dutch language only) on Connexxion's website.
The Dutch rail system provides a frequent direct link from Utrecht to Rotterdam. The bus is there to serve a number of outlying villages.
Utrecht's central rail station is a transport hub, with bus stations on both sides of the station. Most of the "out of town" bus routes pick up at the bus station on the western side of the station.
Connexxion are not alone in operating into Utrecht from further afield. Arriva (website only in Dutch) also operate several services into Utrecht.
In the Netherlands, longer-distance coach services tend to complement the railway system, providing links which the rail network doesn't offer.
Two such services into Utrecht are provided by Arriva, branded as Q-Liner.
Veolia (website only in Dutch) also operate longer-distance services into Utrecht from the province of Brabant, using BrabantLiner as their brand name.
Fares on public transport into and within Utrecht are paid using the OV-Chipkaart, the smartcard for public transport throughout the Netherlands.
Although the bus operators' websites are only in the Dutch language, public transport information (irrespective of operator) can be found in English here.
The start of the U-OV concession brought a large number of new buses onto the streets of Utrecht in December 2013. Nevertheless, images on the busfoto.nl website show that a number of buses from Connexxion and GVU, including the bi-artics, have passed to U-OV and continue to ply the streets of Utrecht, at least for the time being.
Other cities where I have found bi-articulated buses include Hamburg, Luxembourg and Geneva; I have also found bi-articulated trolleybuses in Geneva, as well as Zürich and Luzern.