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Solingen: Two new lines with battery trolleybuses and the official project completion

Inauguration of the " lines 691 and 694 on 7 May 2024 | © Christian Marquordt

Solingen converted two more routes to battery-trolleybus operation (Batterie-Oberleitungs-Bus BOB) and celebrated the official conclusion of the funding project to procure the vehicles.

Trolleybus since 1952

In 1952, Solingen opened its trolleybus service, which very quickly became one of the largest German trolleybus companies – at times 80 vehicles were in operation – and is now one of the last three in Germany (Solingen, Esslingen and Eberswalde) to rely on this mode of transport.

The trolleybus in Solingen was born out of necessity. During the Second World War, the city’s tram infrastructure had been largely destroyed and rebuilding it would not only have been very expensive, but also difficult. The city’s geographical location on the edge of the Bergisches Land and the Rhine Valley plays a significant role here: rail-based vehicles always have a much harder time travelling uphill/downhill than buses. And this applies to Solingen in any case: there is hardly any really flat route. Line 684 in the direction of ‘Widdert Schule’ is a good example: there is a section here with a 10 % gradient.

The Uerdingen ÜH III s

The trolleybus turned out to be a splendid solution for Solingen. By 1959, 62 trolleybuses of the first generation had been bought, all of the legendary ‘Uerdingen ÜH III s’ model with components from Henschel. Later, a second-hand purchase from Bochum-Gelsenkirchener Straßenbahnen, previously their trolleybus 5 of the same type, was added as bus no. 63. Further 4 ÜH IIIs came later from the Minden.

Solingen’s first generation of trolleybuses was finally completed with six ‘Henschel HS 160 OSL’ solo trolleybuses and six ‘Henschel HS 160 OSL-G’ articulated trolleybuses.

On 30 December 1975, bus 59, an Uerdingen ÜH III s from 1959, appears at the Weidenstraße depot. First registered on 18 December 1959 – the author’s birthday! | © Christian Marquordt
Trolleybus 28, a Krupp/Ludewig TS 2 from 1971, at the Krahenhöhe loop on 18 October 1985 | © Christian Marquordt

A Solingen ‘home-grown’ trolleybus

The second generation of trolleybuses went into operation in 1968. By 1974, a total of 80 very unusual trolleybuses had been built. The 12 metre long, three-axle solo trolleybuses were very much based on the Italian ‘filo buses’ (literally translated as ‘wire bus’) of the 1950s and early 1960s, and were designed not least by the then head of the Solingen municipal utilities, Dipl-Ing. Helmut Meis. The bodies were supplied by the well-known Ludewig body factory in Essen-Altenessen, and the chassis was built using Krupp components. Interesting note: Mercedes had just taken over Krupp’s commercial vehicle division and ended the construction of Krupp lorries and buses – but components (such as the drive unit) were still supplied under the Krupp name for Solingen’s new trolleybuses. This explains why Solingen’s second generation of trolleybuses is known as the ‘Krupp/Ludewig TS’ (TS = Trolleybus Solingen).

MAN from Vienna

The third-generation trolleybuses came from MAN. There were 21 articulated trolleybuses of the ‘SG 200 HO’ type (actually 22, because the burnt-out trolleybus 7 was replaced by a replica two years younger with the same trolleybus number) and 46 three-axle rigid trolleybuses of the SL 172 HO type. They were also somewhat unusual: They were again three-axle buses, for better traction on the hunt routes in Solingen. And their place of birth was also unusual: Although the Federal Motor Transport Authority listed them as MAN and they also had MAN vehicle identification numbers (chassis numbers), they were built in Vienna-Liesing by MAN subsidiary Gräf & Stift (‘MAN Special Bus’).

MAN SL 172 HO trolleybus 36 on the famous trolleybus turntable in Burg on 17 August 2009  | © Christian Marquordt
When it was still brand new: Berkhof trolleybus 176 brandnew at the depot on 12 June 2001 | © Christian Marquordt

The fourth generation: Dutch / Belgian / Swiss

Solingen’s fourth generation of trolleybuses is quite colourful. It consists of 50 articulated trolleybuses, purchased between 2000 and 2009, from three different manufacturers. The trolleybuses 171 to 185 came from the Dutch manufacturer Berkhof (now merged into VDL) and were of the ‘Premier AT 18’ type. Today, all of the Berkhof trolleybuses have been decommissioned, although the author was told at the ‘70 years of trolleybuses in Solingen’ anniversary in 2022: ‘The Berkhof trolleybuses are the best of our oldest trolleys.’

Van Hool from Lier in Belgium supplied 20 trolleys of its ‘AG 300 T’ type, 14 of which are still in daily use today (series 251 to 270). And in 2009, Hess from Bellach in Switzerland supplied a further 15 articulated trolleybuses of its type ‘BGT-N 2 C’ (often referred to as the ‘Swisstrolley’), buses 951 to 965. The Hess vehicles were procured for two extensions of line 683 in the Burg district and in Wuppertal-Vohwinkel. Both extensions were not spanned with contact wire – not in Burg so as not to disturb the historic townscape of Burg, and not in Vohwinkel because of a low railway bridge. The Hess articulated trolleybuses were therefore fitted with generator sets from the Trier-based manufacturer Kirsch, the main element of which is a diesel engine from FPT (Fiat Power Train).

On the way to the ‘BOB’

For some time now, decision makers in Solingen have been thinking about how to expand electric transport in the city. Although line 684 had been extended from the city centre to Hasselstraße and two diesel bus lines had been electrified as trolleybus lines 685 and 686 years ago, the cost to install overhead lines for each new electric line was still very high.

Meanwhile, the battery-electric bus entered the scene. And, although their range is still rather limited for the time being, they have been used successfully in one city or another. Bonn, for example, trialled a Chinese BYD back in 2012 and a Dutch Ebusco in 2013. Both did what they were supposed to do, but had to ‘plug in’ relatively often.

Then someone had a clever idea: couldn’t you equip a battery bus with trolley poles, not only drive it with the electricity from the overhead contact line where it runs under trolleybus overhead contact lines, but also recharge its batteries, and let it run on sections of the route without overhead contact lines using the electricity from the batteries? That was the birth of the ‘In-Motion Charger’ (IMC), known in Solingen as the BOB (Batterie OberleitungsBus = battery overhead line bus) for short.

In 2018, the first four battery-powered trolleybuses, vehicles 861 to 864, went into operation in Solingen.  They are of the ‘Solaris Trollino 18.75’ type, often referred to in Solingen with the type suffix ‘BOB’, while Solaris is more likely to refer to them as ‘Solaris Trollino 18.75 IMC’.

One of the first four “BOB” still in the Solaris Trollino III design | © Juanjo Olaizola
Solaris Trollino 18 “BOB” on line 695 | © Christian Marquordt

These new vehicles went into service on the previous diesel bus route 695 (Meigen – city centre – Abteiweg). The route is partly identical to that of trolleybus route 683. When the bus is travelling here, it ‘starts up’, runs and recharges its batteries from the overhead line, and covers the rest of the route from its batteries. Only 30 % of the route needs to have overhead contact lines; the bus manages the remaining 70 % from its batteries. SWS operations manager Laise: ‘The fact that the buses are constantly recharged from the overhead line means that their range is practically unlimited, unlike a battery-only bus.’

Meanwhile, the BOB fleet in Solingen has grown to a total of 36 buses, with 20 articulated buses (861 to 880) and 16 solo buses (201 to 216). All 36 are of the Solaris types ‘Trollino 18.75 BOB’ and ‘Trollino 12 BOB’. Laise: ‘The solo buses replace diesel buses, the articulated buses older pure trolleybuses’. The last buses ordered are about to be delivered, with a delay of a few months.

Since 7 May 2024, the two lines 691 and 694 have now also been converted to operation with BOB (previously there had already been test runs with the BOB on these lines). Line 691 runs from the main station (Ohligs station) to Lukaskrankenhaus, line 694 from the main station to the neighbouring town of Leichlingen. Both lines were previously purely diesel bus lines, there was no overhead contact line. And no new overhead lines have been installed. So where does the BOB get its electricity from? It’s simple: lines 691 and 694 have been linked with lines 685 and 686, which were already pure trolleybus lines, so the BOB can recharge perfectly here.

The ribbon in the blue/yellow city colours is cut, from left to right: SWS operations manager Matthias Laise, Federal Transport Minister Wissing, Lord Mayor Kurzbach, SWS Managing Director Leif Reitis and NRW Transport Minister Krischer | © Christian Marquordt


The conversion from line 695 to BOB in 2018 alone led to savings of 147,000 litres of diesel and 334 tonnes of CO2 per year.

Plans for the future

Solingen wants to have no more diesel buses by 2030 (that’s only five and a half years away). Then there will only be ‘BOB’ buses. However, this not only means that all diesel buses will have to be replaced by BOBs by then, it also means that all pure trolleybuses will have to be replaced by ‘BOBs’ by then. So: farewell, Berkhof (they are no longer in the fleet anyway, even though they were considered very solid), but also: farewell Van Hool and farewell Hess.

There were times when SWS communicated that due to the long range of the BOB without overhead contact lines, they could even consider removing trolleybus overhead contact lines in the city. The new SWS operations manager, Matthias Laise, no longer wants to hear about this. ‘We are looking into setting up catenary islands on new lines to be converted from diesel to BOB so that our BOBs can recharge there.’

Solingen? It remains exciting!