by Adrian-Liviu Dorofte

Test track in Wiesbaden: an urban challenge for the Mercedes-Benz Citaro Euro VI

Clean, responsive, comfortable and user-friendly. Introducing the Mercedes-Benz Citaro with new drive technology that meets the Euro VI emissions standard. And has already made a superb impression on demanding routes today.

Three doors, impressive lighting – the new Citaro

The optional pivot-and-slide doors open within seconds to welcome both driver and passengers aboard. An LED light strip illuminates the step, while another light strip in the door frame overhead highlights the entire entrance – the new Citaro certainly makes it easy for passengers, extending an invitation to hop on board.

Driver’s area upgraded with new door locking system

A new optional feature for the Citaro is the electromagnetic locking system for the door to the driver’s cab, activated via a button in the cockpit. In the test bus, a partition extending across half the width of the door creates distance from the passengers, yet doesn’t prevent direct contact.
The driver’s area itself is by now well-known: plenty of space with enough storage options for everything from the driver’s bag to the chilled compartment, to the pen and mug holders. Anyone driving the Citaro also benefits from a cockpit that is comfortable, modern and well-laid-out.

The buttons are exactly where they should be, the four-spoke steering wheel with multifunctional buttons is a comfortable fit. High-quality materials have been used, evident in everything from the pleasant feel of the cockpit cover to the chrome ring of the round air vents. Any driver who takes to the helm of this bestselling bus can expect a first-class working environment.

The new OM 936 located in the rear of rigid bus

Not much more than a subtle rumble can be heard from behind when the new in-line six-cylinder OM 936 engine starts up, one that meets the Euro VI standard with a 7.7 l displacement, 220 kW (299 horsepower) power output and 1 200 Nm torque. In the test vehicle, it has been installed upright in a tower construction. Immediately above this is the radiator. With automatic transmission set to “D” and the parking brake released, the Citaro leaves the ESWE bus depot in Wiesbaden’s Gartenfeldstrasse in the centre of the city, not far from the main train station.

A challenge for any omnibus: Wiesbaden

ESWE is a company that has been closely linked to Mercedes-Benz for many years now. The first transit buses appeared in Wiesbaden as far back as 1922, from a predecessor of the current Daimler AG. Whether during the changeover from trams to buses in 1929 or today: vehicles from Mercedes-Benz have always taken centre stage.

The state capital of Hesse really sets a challenge for buses and their drivers. Wiesbaden may be situated in a wide lowland, yet there are significant height differences to be overcome within the city’s confines. This includes the several kilometres of bus routes 4 and 14 which run parallel to each other, connecting the city centre with the densely populated district of Wiesbaden-Biebrich on the Rhine. This popular duo is the perfect test route for the Citaro and its new Euro IV-compliant drive train.

Straight as a die: Biebricher Allee

The Citaro crosses the Bahnhofsplatz only a few hundred metres from the bus depot, before turning left onto Biebricher Allee and filtering into the flow of traffic on ESWE lines 4 and 14. After reaching just the first stop on Fischerstrasse, the route continues as straight as a die with an increasingly uphill gradient – no easy task.

The distances between the bus stops on Biebricher Allee are short, with additional stops factored in due to traffic lights. Hard work for an urban bus, however a seemingly easy task for the Citaro. Even at half-throttle, the bus moves gently yet purposefully forward, seamlessly merging with the rest of the traffic on the wide avenue. The new compact Euro VI engine with 7.7 l displacement confidently accelerates forward every time.

Powerful acceleration and low engine speeds on gradients

The 6-speed automatic transmission shifts up under these circumstances by 1 250 rpm at the latest, even earlier at less, resulting in extremely low acceleration speeds of around 800 to 900 rpm. The compact engine performs effortlessly, really showing its mettle when faced with an uphill challenge. Proving to have plenty of power even below 1 000 rpm, this is a vehicle boasting peak performance.

The route along Biebricher Allee certainly sets the bar high: kerbs are raised kerbs at the bus stops and bevelled to protect tyres. Tactile lines on the pavement safely guide visually impaired passengers to the front of the bus, while the surrounding road surface has been reinforced to ensure there is no damage caused by the continuous flow of these heavy vehicles.

Turnover is high: the buses travelling along routes 4 and 14 are ten minutes apart during the day, with a bus at the stop every five minutes on average. Due to the high number of passengers commuting, only articulated buses are used – primarily the Mercedes-Benz Citaro.

Transmission shifts up very early on downhill stretches

The route peaks after around a kilometre. It gets easier for the Citaro from this point on, rolling down in the direction of Wiesbaden-Biebrich. Halfway there is the Landesdenkmal stop: to the right an obelisk and a statue commemorating Duke Adolf of Nassau (later the Grand Duke of Luxembourg) and, on the opposite side of the avenue, the large sparkling wine cellar and visitor attraction.

The Mercedes-Benz Citaro keeps on going however. On downhill stretches, its shift points are extremely low at only around 1 000 rpm. Acceleration speeds reach around 800 rpm. And despite this, the drive train operates almost without vibration. The bus then traverses the A66 motorway, connecting Wiesbaden to Frankfurt and Rüdesheim.

The route divides after the stop Herzogsplatz, taking the one-way street Strasse der Republik and then Rathausstrasse into the heart of the densely populated district of Wiesbaden-Biebrich.
Business and residential buildings to the left and right, rows of snugly parked cars, as well as plenty of pedestrians – a challenge easily managed by the driver from his spacious Citaro cab.

Typical Citaro feature is and remains its manoeuvrability

Almost 4.5 kilometres into the journey, the banks of the Rhine are in sight. The bus lines separate here, with the Citaro veering right along route number 14. The right-angled approach to Rheingaustrasse requires special attention, calling on the articulated bus to use two lanes when turning, generally advised as a safety precaution. The driver of the Citaro has no problems making a clean turn here thanks to the vehicle’s small turning radius and superb view.

Approximately 300 metres later, passengers on the right-hand side of the bus have the opportunity to admire the Baroque Biebrich Palace. Once the residence of the Nassau dynasty, today it is used for events such as state government receptions. It is also poses as the civil registry office, providing the perfect backdrop to romantic wedding photos. Over the Whitsun holiday period each year, the international equestrian elite meet in the palace gardens to take part in Wiesbaden’s “Pfingstturnier” tournament. The Citaro follows its own course on a daily basis, travelling from stop to stop along Rheingaustrasse with its fancy villas.

The Citaro urban bus: smooth chassis, quiet drive

After just a few hundred metres, the bus turns right onto Albert-Schweitzer-Allee. Here, on the flat, the shift points are between 1 000 and 1 200 rpm when accelerating, at 50 km/h the Citaro conserves fuel and remains quiet with 1 000 rpm.

On this slightly uneven surface, both driver and passengers also benefit from the chassis and suspension set-up of the bus. The front axle with independent wheel suspension absorbs any inconsistencies in the road surface and prevents any disruption to the Citaro’s steering capability.

The new engine masters the uphill challenge

Another kilometre into the journey and the route leads along the Äppelallee back to Herzogsplatz and Biebricher Allee. Then uphill to Wiesbaden city centre, a real test for the Citaro with several stops and traffic lights along the 1.5 km stretch of slope.

Despite acceleration at full throttle, the engine remains quiet and discreet. It is the passengers to the rear of the bus who benefit in particular from the smooth running characteristics of the in-line six-cylinder engine with common-rail injection, from the low engine speeds and sophisticated noise insulation.

Anyone travelling at night will notice the new unique ambient lighting in the passenger compartment, available as an optional extra. Additional lamps above the double seats beam either orange or white light, while LED reading lamps can be individually adjusted. A level of comfort almost on a par with coach travel and even greater safety to boot. Another impressive feature of the Citaro is the blue night light.

Efficient retarder decelerates almost to a standstill

The influence of the retarder certainly becomes apparent on the descent into the city: if the bus is equipped with a pitman arm for the third brake, skilled drivers can almost bring the vehicle to a standstill when required.

During this part of the route, the automatic transmission switches up a gear up again with around 1 000 rpm when accelerating - it doesn’t get much resourceful than this!

The test course once again diverts from bus routes 4 and 14 at the main train station, heading back to the ESWE bus depot in Wiesbaden. 10.5 km have been completed in around 40 minutes and 24 bus stops reached. With its new Euro IV-compliant drive train, the Citaro has completed the course with flying colours, powerful acceleration and low-noise operation.

Credits: Daimler AG

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