Trolley Vs Battery Electric Buses - Are trolleybuses a practical alternative?

[Jozhua]

I've seen a lot of debate surrounding the use of Trolleybuses for electrification of the global bus fleet. Some popular transportation/urban planning channels have taken to calling battery buses a "scam".

From my perspective, a battery electric bus fleet > a battery electric car fleet, just as as an ICE bus fleet > ICE car fleet, regardless of the merits of trolleys.

Trolleybuses are sold as being cheaper and less materially expensive, but I'm somewhat skeptical this is the case. I have seen legacy trolley systems working well to this day (Budapest being a good example), but would such a system be built from new today?

Certainly the trolley poles require extra overhead from a driver's perspective, especially over junctions or when passing other vehicles. I would think a modern system may deploy something more high tech than the wheeled poles!

Perhaps there is a place for in-motion charging of battery electric buses on trunk routes, utilising newer technologies such as that seen on the e-highway trials for trucks. This uses computerised tracking systems to keep pantographs attached to the wires.

Overall, I think buses are a massively underappreciated mode and I would like to see a successful decarbonisation strategy for them! What are everyone's thoughts on the subject?

 

[GusB]

Perhaps there is a place for in-motion charging of battery electric buses on trunk routes, utilising newer technologies such as that seen on the e-highway trials for trucks. This uses computerised tracking systems to keep pantographs attached to the wires.

I honestly don't think that we'll see widespread re-introduction of trolleybuses. Battery technology has come on leaps and bounds in recent years, and provides far more flexibility for operators to alter services to meet the needs of a given area, just as diesel buses provided that flexibility when new housing estates (and new towns) were springing up in the post-war era.

Having said that, where buses currently use pantograph equipment to provide opportunity charging, I don't see why it couldn't be used to provide charging on-the-move on a high-frequency corridor where services then diverge to serve different areas.

 

[daodao]

I honestly don't think that we'll see widespread re-introduction of trolleybuses. Battery technology has come on leaps and bounds in recent years, and provides far more flexibility for operators to alter services to meet the needs of a given area, just as diesel buses provided that flexibility when new housing estates (and new towns) were springing up in the post-war era.

Having said that, where buses currently use pantograph equipment to provide opportunity charging, I don't see why it couldn't be used to provide charging on-the-move on a high-frequency corridor where services then diverge to serve different areas.

It seems to me that battery electric trolleybuses would have advantages. The core section of a high frequency service could be wired, but junctions would not be wired (to keep the overhead simple) nor would outer ends of routes where the frequency is lower. In motion charging would enable the battery size (and thus weight) to be minimised, and the vehicle would not need to wait for long periods at termini to be fully re-charged. However, there seems to be an aversion to overhead trolleybus wiring in many cities, most notably Moscow, where the largest trolleybus system in the world was abandoned recently to be replaced by diesel as well as battery buses.

 

[edwin_m]

In some ways the trolleybus has the disadvantages of a bus (high energy consumption, tyre pollution, smaller vehicle size) and of a tram (needs fixed infrastructure), although this is something of an over-simplification. For very high passenger numbers a tram carries more people at lower cost and for low ones a battery bus allows a service free of (exhaust) emissions without the need to put overhead line above every route. There may be a niche in between for trolleybus, but it's a pretty small niche and could be so small as to be non-existent.

The pantograph charging systems require precise positioning of the vehicle because the two sides of the pantograph need to touch the two sides of the electrical supply. To do this on the move would need some sort of guidance for the vehicle. A conventional trolley pole doesn't have this restriction and indeed normally allows the vehicle to change lane.

 

[johncrossley]

I would like to see a successful decarbonisation strategy for them! What are everyone's thoughts on the subject?

That's already in progress. Several places have already largely stopped buying diesel buses. For example China, London and the Netherlands.

 

[Ken H]

A trolleybus is such a simple bit of kit they should be cheap to make in quantity. A battery/trolley bus could have a go anywhere capability with the caveat it would need a decent amount of trolley running to keep the batteries topped up.
They are called trolley buses because the original design had a 4 wheeled trolley running under the wires. The latest ones in UK had a carbon insert in a groove that ran under the wires.
only problem with a bi-mode is attaching/detaching the trolley from the wires.
I dont see a modern trolleybus overhead to be much more intrusive than a tram overhead.

 

[Sir Felix Pole]

The Leigh guided busway in Greater Manchester would be a good place for trolleybuses, with battery operation for the continuation of the route in Manchester City Centre and down Oxford Road, and permitting recharging on the electrified sections. Stagecoach's high frequency and quite long route 43 from Piccadilly to the Airport via Oxford Road and Northenden would be another candidate - it is battery operated but requires a high vehicle requirement to allow for recharging. I have seen buses stranded en-route, or terminated at Northenden in order to visit the depot there for a 'top-up'.

 

[Jozhua]

I honestly don't think that we'll see widespread re-introduction of trolleybuses. Battery technology has come on leaps and bounds in recent years, and provides far more flexibility for operators to alter services to meet the needs of a given area, just as diesel buses provided that flexibility when new housing estates (and new towns) were springing up in the post-war era.

Having said that, where buses currently use pantograph equipment to provide opportunity charging, I don't see why it couldn't be used to provide charging on-the-move on a high-frequency corridor where services then diverge to serve different areas.

It seems to me that battery electric trolleybuses would have advantages. The core section of a high frequency service could be wired, but junctions would not be wired (to keep the overhead simple) nor would outer ends of routes where the frequency is lower. In motion charging would enable the battery size (and thus weight) to be minimised, and the vehicle would not need to wait for long periods at termini to be fully re-charged. However, there seems to be an aversion to overhead trolleybus wiring in many cities, most notably Moscow, where the largest trolleybus system in the world was abandoned recently to be replaced by diesel as well as battery buses.

I agree with both of these points, about it being useful for in-motion charging in high frequency areas. You can reduce battery capacity requirements and increase the utilisation of the buses!

In some ways the trolleybus has the disadvantages of a bus (high energy consumption, tyre pollution, smaller vehicle size) and of a tram (needs fixed infrastructure), although this is something of an over-simplification. For very high passenger numbers a tram carries more people at lower cost and for low ones a battery bus allows a service free of (exhaust) emissions without the need to put overhead line above every route. There may be a niche in between for trolleybus, but it's a pretty small niche and could be so small as to be non-existent.

The pantograph charging systems require precise positioning of the vehicle because the two sides of the pantograph need to touch the two sides of the electrical supply. To do this on the move would need some sort of guidance for the vehicle. A conventional trolley pole doesn't have this restriction and indeed normally allows the vehicle to change lane.

You have a point, using trams for the high-frequency/capacity core sections and then buses feeding in, or providing service on less heavily utilised routes.

To be honest, you could also just look at fixed infrastructure such as charging at Terminus, or perhaps even having multiple "charging" connections to discrete battery packs - I'm aware there are probably power management systems on buses that do this!

That's already in progress. Several places have already largely stopped buying diesel buses. For example China, London and the Netherlands.

True - even if battery buses are "imperfect", they are a solution that exists today!

The Leigh guided busway in Greater Manchester would be a good place for trolleybuses, with battery operation for the continuation of the route in Manchester City Centre and down Oxford Road, and permitting recharging on the electrified sections. Stagecoach's high frequency and quite long route 43 from Piccadilly to the Airport via Oxford Road and Northenden would be another candidate - it is battery operated but requires a high vehicle requirement to allow for recharging. I have seen buses stranded en-route, or terminated at Northenden in order to visit the depot there for a 'top-up'.

Guided busways could work very well with pantographs!

Always wondered about the 43. The buses are quite pleasant to ride on anyhow.

 

[PeterC]

The technology exists to use pantographs but they would still be best on long runs without lane changes so would be highly suitable for guided busways.

 

[Jozhua]

The technology exists to use pantographs but they would still be best on long runs without lane changes so would be highly suitable for guided busways.

Yeah - I think even Trolleybuses wouldn't make much sense relying entirely on power from overheads. Even a small battery to allow for flexibility during power outages - perhaps this could be something we can deploy on the railways?

I believe most modern Trolleybuses have at minimum a small battery for moving round the depot.

 

[dm1]

However, there seems to be an aversion to overhead trolleybus wiring in many cities, most notably Moscow, where the largest trolleybus system in the world was abandoned recently to be replaced by diesel as well as battery buses.

That closure was almost universally condemned by everyone with any understanding of Moscow's public transport system. Effectively it happened exclusively because the mayor had a personal dislike of the wires, despite even his own experts advising it was a bad idea.

Moscow could have replaced about 80% of the diesel buses in the city with in-motion charging (IMC) trolleybuses, using existing infrastructure, and the rest could have been electrified either using battery electric buses for low-traffic routes, or with a few small extra sections of wires where necessary.

Instead they replaced the trolleybuses nominally with opportunity charging electric buses, in reality mostly with diesel buses. Even many of the electric ones had diesel furnaces as the batteries weren't big enough to supply enough heating power in the winter, and those furnaces didn't have to comply with any emissions regulations, so were even worse than diesel buses...

If it wasn't for this stupidty, Moscow could have had an entirely electric bus network by now, and therefore an entirely electric public transport system. Unfortunately in reality the number of electric buses has fallen significantly since the trolleybus network was closed.

I'm not convinced that it won't make a comeback once there is a new mayor. The economics stack up too well compared to other electric bus solutions - IMC trolleybuses have by far the lowest whole-life cost, and many of the masts, transformers and rectifiers are still in place, even if the wires themselves have been removed.

A trolleybus is such a simple bit of kit they should be cheap to make in quantity. A battery/trolley bus could have a go anywhere capability with the caveat it would need a decent amount of trolley running to keep the batteries topped up.
They are called trolley buses because the original design had a 4 wheeled trolley running under the wires. The latest ones in UK had a carbon insert in a groove that ran under the wires.
only problem with a bi-mode is attaching/detaching the trolley from the wires.
I dont see a modern trolleybus overhead to be much more intrusive than a tram overhead.

That is exactly it. The issue with other types of electric buses is that they have to either spend significant time charging (and therefore out of service, meaning more buses are required for the same service), or they are extremely heavy (because they require large batteries). The beauty of IMC is that you charge on the move, so you can run exactly the same as a diesel bus, with the added reliability advantage since they have far fewer moving parts and make far more sense environmentally as the battery can be much smaller and therefore fewer raw materials are required.

I think many people, particularly those making decisions in the UK have either no experience of trolleybuses, or remember the knackered systems that closed in the 60s, so don't realise that trolleybus technology has developed signficantly since then - dewirements are a rare occurence on modern systems, poles can be raised or lowered automatically at the push of a button and therefore junction designs are simplified considerably.

New depots use CCS for charging IMC buses, with no overhead wires needed there.

Discontinuous electrification might be a new concept for railways, but it has been in daily, reliable use for several years now in trolleybuses. Modern systems only need around 50% of the route wired. In temeperate conditions even 30% is sufficient, since much of the energy demand comes from heating and cooling.

The other problem in the UK, as ever, is deregulation. A bus operator has no incentive to pay for the fixed infrastructure, or just don't have the finances or political clout to get it built, nor do they have the confidence that they will be around long enough to amortise the longer lifetime of trolleybuses and reduced running costs compared to diesel or battery buses. Even London's regulated environment isn't conducive to such investments.

 

[Ken H]

That closure was almost universally condemned by everyone with any understanding of Moscow's public transport system. Effectively it happened exclusively because the mayor had a personal dislike of the wires, despite even his own experts advising it was a bad idea.

Moscow could have replaced about 80% of the diesel buses in the city with in-motion charging (IMC) trolleybuses, using existing infrastructure, and the rest could have been electrified either using battery electric buses for low-traffic routes, or with a few small extra sections of wires where necessary.

Instead they replaced the trolleybuses nominally with opportunity charging electric buses, in reality mostly with diesel buses. Even many of the electric ones had diesel furnaces as the batteries weren't big enough to supply enough heating power in the winter, and those furnaces didn't have to comply with any emissions regulations, so were even worse than diesel buses...

If it wasn't for this stupidty, Moscow could have had an entirely electric bus network by now, and therefore an entirely electric public transport system. Unfortunately in reality the number of electric buses has fallen significantly since the trolleybus network was closed.

I'm not convinced that it won't make a comeback once there is a new mayor. The economics stack up too well compared to other electric bus solutions - IMC trolleybuses have by far the lowest whole-life cost, and many of the masts, transformers and rectifiers are still in place, even if the wires themselves have been removed.


That is exactly it. The issue with other types of electric buses is that they have to either spend significant time charging (and therefore out of service, meaning more buses are required for the same service), or they are extremely heavy (because they require large batteries). The beauty of IMC is that you charge on the move, so you can run exactly the same as a diesel bus, with the added reliability advantage since they have far fewer moving parts and make far more sense environmentally as the battery can be much smaller and therefore fewer raw materials are required.

I think many people, particularly those making decisions in the UK have either no experience of trolleybuses, or remember the knackered systems that closed in the 60s, so don't realise that trolleybus technology has developed signficantly since then - dewirements are a rare occurence on modern systems, poles can be raised or lowered automatically at the push of a button and therefore junction designs are simplified considerably.

New depots use CCS for charging IMC buses, with no overhead wires needed there.

Discontinuous electrification might be a new concept for railways, but it has been in daily, reliable use for several years now in trolleybuses. Modern systems only need around 50% of the route wired. In temeperate conditions even 30% is sufficient, since much of the energy demand comes from heating and cooling.

The other problem in the UK, as ever, is deregulation. A bus operator has no incentive to pay for the fixed infrastructure, or just don't have the finances or political clout to get it built, nor do they have the confidence that they will be around long enough to amortise the longer lifetime of trolleybuses and reduced running costs compared to diesel or battery buses. Even London's regulated environment isn't conducive to such investments.

Most of the trolleybus systems in the UK were minicipal. Tho some were BET* owned. No Idea if subsidised though.

*BET were a congolmerate company who made and operated trams and trolleybuses. They morphed into a bus company as trams and trolleybuses went, and eventually sold their bus companies to the government, which became part of the National Bus Company.

 

[carlberry]

The other problem in the UK, as ever, is deregulation. A bus operator has no incentive to pay for the fixed infrastructure, or just don't have the finances or political clout to get it built, nor do they have the confidence that they will be around long enough to amortise the longer lifetime of trolleybuses and reduced running costs compared to diesel or battery buses. Even London's regulated environment isn't conducive to such investments.

How can deregulation be the problem if it isnt attractive under a regulated environment either? The problem is that the UK doesnt like investing in public transport outside of fixed rail.

If the money is available it's quite possible for any local authority to put up the overhead and either use London contracts or a quality partnership to specify the vehicles to be used on it. It's no different to the Leigh Busway or Bristol's Metrobus roads.

It is however expensive and slow and is taking a bet on where things will be in 5-10 years time. In that timescale it's quite possible that alternatives (battery, hydrogen or even something else) will have come along and make fixed infrastructure appear outdated.

 

[johncrossley]

London is way ahead of the rest of the country when it comes to electric buses.

 

[dm1]

It is however expensive and slow and is taking a bet on where things will be in 5-10 years time. In that timescale it's quite possible that alternatives (battery, hydrogen or even something else) will have come along and make fixed infrastructure appear outdated.

For some reason that line of argument is considered unacceptable for railways (despite the Treasury's best efforts), but is apparently absolutely fine for buses. The same laws of physics apply in both cases.

Battery technology is improving, but some level of fixed infrastructure is in many cases still far more efficient and cost-effective than trying to put all of the technology into the vehicles. Trolleybuses are a mature technology and it is entirely possible to electrify complete bus networks today, without any compromises on cost or operations, whereas purely battery buses (with opportunity or overnight charging) still have significant issues that will remain in the foreseeable future, in particular, high weight due to heavy batteries, power grid capacity, and somewhat problematic battery recycling and production.

In my view it is almost the exact same situation as for railways, but scaled down - for higher frequency corridors (anywhere with more than say, 8 buses per hour per direction), in particular in cities, fixed infrastructure makes a lot of sense, whereas for lower frequency rural or suburban services, other technologies may be better.

How can deregulation be the problem if it isn't attractive under a regulated environment either? The problem is that the UK doesn't like investing in public transport outside of fixed rail.

It is true, that the UK doesn't like investing in any public transport infrastructure other than rail. That is a problem.

The point I was making is that London's tendering system is based on relatively short contracts, that are significantly shorter than the lifetime of a trolleybus, meaning operators would need to win at least two tenders with the same vehicles, with access to the infrastructure in order to amortise their cost. Under a different regulated environment, this would be less of an issue.

In other words - from a system perspective, trolleybus + wires will often be cheaper overall, whereas battery or diesel bus is much cheaper in the short term, but more expensive in the long run, from high battery replacement costs for the former and from fuel and maintenance costs for the latter.

Most of the trolleybus systems in the UK were minicipal. Tho some were BET* owned. No Idea if subsidised though.

Municipal operators are one way to ensure that the operator can benefit from the whole-life costs, since it will be around long enough to benefit from them. Many modern trolleybus systems around the world operate in this way.

 

[Bletchleyite]

It is true, that the UK doesn't like investing in any public transport infrastructure other than rail. That is a problem.

Mostly. But it isn't 100% true, for instance the PTEs like building big, fancy bus stations, as do some Councils.

 

[NorthKent1989]

I think trolley buses could be useful for longer distances trunk routes in London, like the 18, 207/427/607, 180 and the 53/453 routes and also radial routes like the X26, the 269, the 119 and the X140, as the wires could act as charging points on some stretches of the route.

But shorter routes can be solely battery where they can charge at the end of each terminal.

Theres room for both in my opinion.