In 2020, the Ruhrbahn, the public transport operator in Essen, the fourth largest city in North Rhine-Westphalia (after Cologne, Düsseldorf and Dortmund) with around 600,000 inhabitants (11th largest in Germany), and its western neighbour Mülheim (Ruhr), launched three neighbourhood bus lines in the south of the city around the Werden district, namely lines 182, 190 and 192. Line 190 connects the Essen-Werden S-Bahn station with the Ruhrlandklinik hospital, which is located on the heights above the Ruhr valley. Lines 182 and 192 are counter-running circular lines with the route S-Bahn station Werden – Fischlaken – Heidhausen – S-Bahn station Werden (line 182) and vice versa (line 192).
Line 190 has a single carriage, which covers the ten kilometres of its route to and from Werden S-Bahn station in one hour. Note: due to the route’s narrow, steep and winding roads, there should not be a second bus on the line, as there is not enough space for two carriages to pass each other at many points along the route. The roads are too narrow in places – and that in a large city in the industrial region of the Ruhr…
There are two buses each on lines 182 and 192, i.e. a total of four buses, and both lines run every 20 minutes. Each of the four buses therefore makes a round trip from the Werden S-Bahn station every 40 minutes.
In 2020, Ruhrbahn purchased six Mercedes-Benz 519 CDi Sprinter City 75 buses (buses 2094 to 2099) for the five routes on these three lines, which were built at the Mercedes plant in Dortmund. Mercedes has since sold the Dortmund plant to Tremonia, but the Sprinter minibuses are still being built here according to Mercedes’ design plans, albeit now under the Tremonia brand name.
In 2024, Ruhrbahn expanded its fleet of minibuses with two Mercedes Sprinters with bodies from the Austrian/Slovenian company Kutsenits (K-Bus) with the vehicle numbers 2494 and 2495.
The minibuses are certainly needed, not only on line 190 to the Ruhrlandklinik hospital, but also on lines 182 and 192, some of which are steep, narrow and winding. Full-size 12-metre buses would have difficulties there.
Ruhrbahn and the battery-electric minibuses
The concept of using minibuses on the three routes has proven successful. This is demonstrated not least by the fact that Ruhrbahn added two more vehicles to its ‘fleet’ of buses for these routes last year.
But Ruhrbahn also wants to move away from diesel and towards battery-electric buses on these routes. And so, two battery-electric minibuses were tested in the spring:
- a Northern Irish/Chinese ‘Rightech RB 6’, the result of a collaboration between Northern Irish bus manufacturer Wrightbus and Chinese bus manufacturer King Long
- a ‘Wisdom Sigma 7’, which is produced by the Chinese company ‘Wisdom Motor Corp.’ in the former British Crown Colony of Hong Kong.
The Wisdom Sigma 7 in Essen
The little Wisdom has an interesting history. It first saw the light of day at the beginning of this decade as the ‘Mellor Sigma 7’ from the British bus manufacturer ‘Mellor’ in Rochdale in central England. Mellor purchased the empty body shell of the Sigma 7 from Wisdom Motor Corp. and completed it in its own factory in Great Britain to produce the finished electric minibus. It was used as a test vehicle in Bonn, for example, and three units were sold to Kieler Verkehrs Gesellschaft (KVG). They run on routes on the outskirts of the city where full-size buses would not be viable.
In 2024, Mellor was sold to the Belgian Dumarey Group. Dumarey continues to build minibuses on Iveco, MAN and Mercedes chassis, but the ‘Sigma’ programme in collaboration with Wisdom has been discontinued. Wisdom then made a wise decision: the Sigma body shell, which was already in the production programme, will be completed as a finished electric bus.
Jebsen & Jessen in Hamburg, which had previously been Mellor’s distribution partner, was won as the distribution partner for the ‘Sigma series’ for the German-speaking part of Europe. Jebsen & Jessen was able to deliver three more ‘Sigma 7’ buses to Kiel’s KVG, this time no longer as Mellor, but as Wisdom.
And Wisdom has given the little Sigma a facelift that makes it look more modern.
Test on the neighbourhood bus lines in the south of Essen
The small Sigma 7 is – as is standard today – a low-floor bus. It can carry 27 passengers, 14 of whom can be seated and 13 of whom can stand. The seats are made by the German manufacturer Kiel, which supplies seats for a large number of public buses. There is a manually operated wheelchair ramp at the wide centre door. This does not need to be operated with a key stick; instead, the driver can operate the ramp more conveniently with a cable pull. This means they do not have to bend down so far.
The electric motor comes from the manufacturer ‘Hande’ and has a peak output of 150 kW (continuous output 70 kW). The batteries are supplied by the world’s largest battery manufacturer CATL, have a capacity of 127 kWh and use LFP (lithium iron phosphate) cell chemistry. The vehicles operate on neighbourhood bus routes from 5 a.m. to 11 p.m. Consumption measurements showed that the demonstration vehicle consumed 4% of the electricity stored in the batteries on a 10-kilometre route with the air conditioning running, and would therefore only consume 72% of its electricity when in use from 5 a.m. to 11 p.m. So there is no need to worry that the vehicle could run out of power. Even if power consumption is not quite as favourable in winter with the heating running, the bus will not break down and will always be able to cover its 180-kilometre daily mileage. With ease, so to speak.
The small Sigma 7 has twin tyres on the rear axle. It is 6.99 metres long and 2.10 metres wide.
Impressions from the test drive: the routes served by Essen’s local buses are sometimes quite steep. Not only on line 190 on the way to the Ruhlandklinik hospital, but also on line 182 in the Fischlaken district. The author was impressed by how the little Sigma sprinted up the inclines. No diesel bus could have kept up. The chances of keeping to the timetable are therefore not bad, even if there is a traffic jam somewhere, as the potential to make up for a delay is definitely there.
And when it’s a steep downhill slope? Then the little Sigma recovers and recharges its batteries.
And otherwise? Passengers are transported in a pleasant and comfortable manner.
25.06.2025
