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Post by stuckonthe486 on May 24, 2017 11:46:29 GMT
Apologies if this topic has been tackled before, but being a bit clueless as to vehicle types, I've a question. It came after a discussion about an air quality campaign at a school where the parents are, naturally, pushing for cleaner buses on the routes outside (thanks to the tender section of this board, I can see most of their routes are due hybrids in their next contracts, which are due soon, so thanks to all those who post that info). I was wondering about bus emissions and had a glance at the most recent bus fleet audit, particularly table 3: content.tfl.gov.uk/bus-fleet-audit-130117.pdfIt's clear now that there's a welcome shift to hybrids and zero emission buses in the double decker fleet. But very little's happened with single deckers - in fact, there are fewer hybrids than there were in 2011, and it looks like TfL is still experimenting with hybrid/zero emission single decks after all this time. Even though I'm sure the first zero-emission buses to be demonstrated in London were single decks. It does seem very odd, particularly as there is a strain of political/resident group opinion in London that will blame everything on buses - particularly in areas where little single-deckers might go down side roads past schools and other sensitive locations. Is there any one reason for this? Is it political (ULEZ plus greater visibility of double deckers) or is it an industry issue (cost/reliability)? |
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Post by redexpress on May 24, 2017 12:20:19 GMT
Apologies if this topic has been tackled before, but being a bit clueless as to vehicle types, I've a question. It came after a discussion about an air quality campaign at a school where the parents are, naturally, pushing for cleaner buses on the routes outside (thanks to the tender section of this board, I can see most of their routes are due hybrids in their next contracts, which are due soon, so thanks to all those who post that info). I was wondering about bus emissions and had a glance at the most recent bus fleet audit, particularly table 3: content.tfl.gov.uk/bus-fleet-audit-130117.pdfIt's clear now that there's a welcome shift to hybrids and zero emission buses in the double decker fleet. But very little's happened with single deckers - in fact, there are fewer hybrids than there were in 2011, and it looks like TfL is still experimenting with hybrid/zero emission single decks after all this time. Even though I'm sure the first zero-emission buses to be demonstrated in London were single decks. It does seem very odd, particularly as there is a strain of political/resident group opinion in London that will blame everything on buses - particularly in areas where little single-deckers might go down side roads past schools and other sensitive locations. Is there any one reason for this? Is it political (ULEZ plus greater visibility of double deckers) or is it an industry issue (cost/reliability)? There's an enormous difference between a hybrid bus and a zero-emission one. Hybrid buses are still essentially diesel-powered vehicles, they just use less fuel and have lower emissions levels. A hybrid drivetrain is not a magic solution that reduces environmental impact to zero! Unfortunately too many people latch onto the "hybrid" label as if a hybrid bus is automatically better than a conventional diesel. It's not as straightforward as that, especially if you compare the emissions of older hybrids with newer EuroVI-compliant diesels. In the case of single-deckers I believe that the extra weight of the hybrid system (including batteries) tends to outweigh the benefits - or at least it makes the environmental gains negligible. Bear in mind that most single-deckers in London are lightweight models that are already quite fuel-efficient. Zero-emission single-deckers, on the other hand, are worthwhile, but they are still very expensive for now. Apart from the experimental hydrogen-powered buses, the zero-emission buses in use in London are plug-in electric vehicles which also require major investment in the charging infrastructure. None of this comes cheap. |
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Post by stuckonthe486 on May 24, 2017 12:30:39 GMT
There's an enormous difference between a hybrid bus and a zero-emission one. Hybrid buses are still essentially diesel-powered vehicles, they just use less fuel and have lower emissions levels. A hybrid drivetrain is not a magic solution that reduces environmental impact to zero! Unfortunately too many people latch onto the "hybrid" label as if a hybrid bus is automatically better than a conventional diesel. It's not as straightforward as that, especially if you compare the emissions of older hybrids with newer EuroVI-compliant diesels. Thank you - yes, I probably should have made that clearer, especially with the issues surrounding the early versions of the New Bus For London. I live just off one of the backstreet bits of the 380, which is now getting new vehicles; is it simply that a lightweight new Euro VI single-decker will be as clean as a hybrid weighed down by batteries, while the weight of a double-decker makes the switch to hybrid more worthwhile? |
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Post by redexpress on May 24, 2017 12:58:14 GMT
There's an enormous difference between a hybrid bus and a zero-emission one. Hybrid buses are still essentially diesel-powered vehicles, they just use less fuel and have lower emissions levels. A hybrid drivetrain is not a magic solution that reduces environmental impact to zero! Unfortunately too many people latch onto the "hybrid" label as if a hybrid bus is automatically better than a conventional diesel. It's not as straightforward as that, especially if you compare the emissions of older hybrids with newer EuroVI-compliant diesels. Thank you - yes, I probably should have made that clearer, especially with the issues surrounding the early versions of the New Bus For London. I live just off one of the backstreet bits of the 380, which is now getting new vehicles; is it simply that a lightweight new Euro VI single-decker will be as clean as a hybrid weighed down by batteries, while the weight of a double-decker makes the switch to hybrid more worthwhile? I doubt the new diesels will be *as* clean as a hybrid, just that the difference isn't enough to make the extra cost worthwhile. They should also have stop-start technology, which will avoid unnecessary emissions while idling and should give anti-bus campaigners one less thing to whinge about. They'll certainly be cleaner than the Optare Tempo hybrids that briefly ran on the 380 a couple of years ago - those used earlier technology and were based on a heavyweight chassis. |
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Post by snoggle on May 24, 2017 13:07:49 GMT
There's an enormous difference between a hybrid bus and a zero-emission one. Hybrid buses are still essentially diesel-powered vehicles, they just use less fuel and have lower emissions levels. A hybrid drivetrain is not a magic solution that reduces environmental impact to zero! Unfortunately too many people latch onto the "hybrid" label as if a hybrid bus is automatically better than a conventional diesel. It's not as straightforward as that, especially if you compare the emissions of older hybrids with newer EuroVI-compliant diesels. Thank you - yes, I probably should have made that clearer, especially with the issues surrounding the early versions of the New Bus For London. I live just off one of the backstreet bits of the 380, which is now getting new vehicles; is it simply that a lightweight new Euro VI single-decker will be as clean as a hybrid weighed down by batteries, while the weight of a double-decker makes the switch to hybrid more worthwhile? I suspect it is a cost and capacity issue. A double decker hybrid can basically keep its capacity equivalent to a diesel decker so TfL don't have to increase the number of vehicles for a given capacity on a route. That is NOT the case yet, for example, with an all electric decker such as the BYDs on the 98. They are incredibly heavy and have a much reduced carrying capacity. You would need vastly more of them to give a defined level of capacity on a route. The same issue applies with single deckers. Hybrid single deckers are much too heavy meaning a lower carrying capacity to meet axle weight concerns. Furthermore the market place is pretty immature for diesel electric hybrid single deckers - there's no great push in the market place for them so they're not cheap nor has the technology been pushed on as it was with double deckers. As Mr Redexpress said the market has split for single deckers - we have lightish fuel efficient euro6 diesel single deckers or we have heavy and expensive all electric single deckers. TfL has dabbled with all electrics and hydrogen for Zone 1 because of ULEZ requirements and because it doesn't have to buy many of them!!!!! Hence all the screaming on here when single deck routes running into Victoria kept diesel buses - people thought they'd be electric but Victoria approached from the west is not in the ULEZ so euro6 single decks are the answer. The sole exceptions to this are the C1 and 70 but they had extra government funding and, I think, some funding from RATP whose subsidiary London United won the contract to run those services. Money talks but that's a rare exception in recent times. It is also worth bearing in mind that many single deck routes are not remotely commercially viable and it would be ludicrous for TfL to push up the cost base needlessly by buying heavier, more costly buses and then needing even more of them to give the required capacity. Heck even the very busiest single deck routes like the 235 have only gained euro6 single deckers and not hybrids or all electrics. The alternative if people insist on zero emission buses in the suburbs will be *no* bus service because the TfL budget cannot carry the cost, Mayoral policy doesn't require it and technology cannot yet provide a cheap zero emission bus that gives a reasonable carrying capacity. There will come a point where routes will have to be withdrawn or cut back if people are insistent on costly technology. All that does is make the bus service even less attractive and will force people into cars which is not the right answer. I appreciate that what I am saying will not be popular and has not been articulated by politicians but we know what TfL's response to declining demand is - take out cost. The flip side to this is not to add extra cost when you already have a poor commercial situation and high subsidy. The restructured Orpington network shows this - every improvement was funded by a cut to service levels or removals of routes or sections of route to keep the overall resource level low. Also few, if any, new vehicles being used. That same philosophy would be applied if resident groups go on the war path over "clean buses". People need to consider the big picture - do you want a low emission bus service that people want to use or do you want a zero emission non bus service because your demands forced TfL to scrap the service altogether or else cut it back to a few trips per day. |
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Post by stuckonthe486 on May 24, 2017 13:34:24 GMT
Thanks both for your really interesting answers. There have been some air quality studies near me and the people carrying them out certainly started out by trying to prove the 380 made the local air worse, even putting an emissions tube in at the rear of a bus stop (even though air quality experts advise against this - I've been involved in a few studies myself). Of course, it proved absolutely nothing of the sort - the main problems were and remain rat-running and school run traffic.
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Post by snowman on Sept 20, 2017 10:42:18 GMT
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Post by redexpress on Sept 20, 2017 11:34:48 GMT
Interesting comments from Daimler about stop-start in that article. Specifically that they are "vehemently against" the idea of stop-start for buses, and that it can be "counterproductive". So if they have introduced a stop-start option for the Citaro, it would seem to be something they've done purely because customers have asked for it, not because they think it's a good idea. EDIT: Direct link to the article in case anyone doesn't want to faff around with the digital edition of the full mag |
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