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Post by pacific on May 30, 2012 9:43:54 GMT
Interesting how TfL limits the acceleration of busses. The current limit is more than good enough for London and the E400 and B9TLs perform far better than the old Metrobuses and Gardner-powered Olympians.
It's also pretty amazing at the wealth of options operators can have with the same engine. The Cummins L10 coming in from 215hp going upwards of 300! The Ex-Dublin Bus/Happy Al's Volvo Olympian, now owned by a local coach company in Dagenham managed 50mph with the ZF Gearbox. My uneducated guess tells me it's still at 215hp. Pump up the hp and it will actually be gearbox limited!
The First Volvo B9TLs doing the X1 through Norwich clearly had extremely powerful, and different engines to that of First Capital's B9TLs. I wonder if they're 62mph capable and limited...
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Chris M
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Post by Chris M on May 30, 2012 16:36:27 GMT
One question, though. Is there a speed limit if the vehicle is carrying standing passengers? National Express coaches don't carry standing passengers, but any "bus" could use a motorway or dual carriageway. If it does, is there a speed limit if the vehicle is carrying standing passengers, or if it is certified to carry standing passengers? The X25 service between Weston-super-Mare and Cribbs Causeway uses the M5 as part of it's journey. My understanding is that standing passengers are not allowed to be conveyed on the motorway sections of the route. The speed limit is 62mph as for coaches, but I'd be very surprised if the buses First use on the service could get anywhere near that on the flat, let alone on the steep hills in the area. |
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Post by norbitonflyer on May 30, 2012 20:54:53 GMT
Time was when LT's route 140 ran some journeys on the M4 Heathrow Airport spur, with open-platform RTs and, later RMs.
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Post by plymothian on Jun 3, 2012 19:25:00 GMT
According to the DSA Official Theory Test for PCVs, which I'm currently studying:
Buses after 1996 must be fitted with a limiter set at 62mph/100kph
and the national speed limit for a dual carriageway is 60mph, 70mph on a motorway (though obviously not possible with a limiter)
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Post by deansullivan on Jun 4, 2012 10:17:42 GMT
Interesting how TfL limits the acceleration of busses. The current limit is more than good enough for London and the E400 and B9TLs perform far better than the old Metrobuses and Gardner-powered Olympians. Found it! So for info, here is the spec for acceleration rates on newly delivered London Buses: Acceleration Rates The combined engine and transmission acceleration controls should limit the bus to a) A maximum rate not below 1.2 m/s2 and not above 1.7 m/s2 on full free acceleration. b) At any point during the acceleration period a range of not below 0.4 m/s3 and not above 0.5 m/s3 should be maintained. c) At full acceleration in the fully laden condition a maximum road speed of 25kph should not be exceeded within the first 10 seconds of acceleration. The rate ranges above should be capable of being delivered within their maximum in the unladen condition and within their minimum in the fully laden condition. Dean |
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Post by notatraindriver on Jun 4, 2012 21:07:27 GMT
Thanks for that information. Wow so a fully laden vehicle shouldn't attain 25 kph (15 mph) in less than 10 seconds? To give an idea of how slow that is, fast double deckers could reach 50 kph (30 mph) in around 10 seconds. Tube trains and certain mainline trains can easily get to 15 mph in less than 10 seconds!
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Post by phillw48 on Jun 4, 2012 21:56:37 GMT
The trolleybuses were well known for their acceleration, far quicker off the mark than most contemporary cars.
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Post by roythebus on Jun 15, 2012 9:22:39 GMT
Yes, a lot of "I thinks" on here and common sense from Dean Sullivan and Norbiton Flyer. Dean should know his stuff as he has a CPC!
I had a 1970's AEC Reliance that would do about 85 mph with a 760 engine and semi-auto gearbox, but was exempt from having a speed limiter due to its age and the fact that VOSA said that by design it was incapable of exceeding 65 according to their data, but "don't get caught". It was bizarre that you could have an older coach with no seat belts legally doing 70 whereas a modern coach with belts and ABS brakes is limited to 62mph/100kmh.
I once rebuilt a Reliance engine for Mitcham Belle. that coach had a ZF 6 speed box and on a test run on the M4 I was overtaking a more modern coach at about 70, then changed into 6th! I ran out of motorway before I could find out what it would actually do.
The same coach was involved in an incident (not involving me) previously; it went onto the M25 from Reigate to go anti-clockwise. The driver accelerated down the slip road; found queueing traffic and hit the brakes. He ended up mounting the grass verge to stop and was branded "a hero" by the local press for doing do. When the brake shoes were examined back at the depot, he'd actually burnt out the linings trying to stop.
There's currently a discussion on the Routemaster owners forum about Routemaster speeds with someone wanting to fit a turbo Scania to one to make it go faster. the problem is as said above, stopping anmd steering it at those higher speeds and the damage that can be caused to the transmission.
Modern buses are indeed limited by computer. Epsom Buses limits his Optare Solos to 30 mph on the grounds that they don't need to go any faster. his accident figures have dropped considerably.
Some of the fastest coaches built were the Midland Red C5 motorway coaches of the early 60's which were reported as doing over 90!
Speeds on older vehicles are limited by the engine speed, the ratio of the differential and tyre size. So the max design speed on an RF for instance fitted with 900x20 tyres and a high ration diff is 48 mph at 1800rpm. Fit 100x20 tyres and the book says it will do 54. fit a low ration diff and 900x20 tyres and it's about 38mph.
My Routemaster with Cummins engine uprated to run at 2400rpm with standard diff will do 54 mph. I hate to thing what it would do with a high ration diff!
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Post by Guest on Jun 15, 2012 11:12:32 GMT
Didn't the Midland Red C5's change drivers whilst on the move?  |
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Post by Charlie J on Jun 15, 2012 17:34:39 GMT
Epsom Buses limits his Optare Solos to 30 mph on the grounds that they don't need to go any faster. his accident figures have dropped considerably. Optare buses can do 30!? ;D ;D |
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Post by notatraindriver on Jun 16, 2012 6:24:02 GMT
Very interesting discussion. Whilst older vehicles are faster it's their ability to stop that worries me. Modern coaches have very powerful brakes and can have powerful engines. A Volvo B13R has engine options of 420 or 460 bhp. Correct me if I'm wrong but older coaches whilst fast wouldn't have more than 300 bhp.
But it's all about economy and not speed nowadays with fuel management systems designed to use as little fuel as possible and kickdowns being disabled. Trains seem to be the only form of public transport where performance is important.
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Post by inspectorsands on Jun 16, 2012 7:37:03 GMT
Having had a quick read through this thread I think the use of the outside lane of a motorway, and maybe some other special roads, is governed by the motorway traffic (England) regulations, possibly the 1982 version off the top of my head, although I vaguely remember from my youth it may have been later. I will ask a traffic colleague and see what they say about the regs.
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Post by inspectorsands on Jun 16, 2012 7:58:03 GMT
Apologies for the double post, I'm surprised how quickly people answer an email on a Saturday morning! It would appear the rules governing the use of the offside or right hand lane of a road governed by the 1982 motorway regs with three or more lanes of traffic proceeding in the smae direction is the The Motorways Traffic (England and Wales) (Amendments) Regulations 1983, a copy of which you will find here www.legislation.gov.uk/uksi/1983/374/regulation/3/madeI'm going to stop now before I turn this into an episode of yes minister. |
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Post by anthony263 on Jun 16, 2012 9:49:27 GMT
Epsom Buses limits his Optare Solos to 30 mph on the grounds that they don't need to go any faster. his accident figures have dropped considerably. Optare buses can do 30!? ;D ;D Surprising isnt it? especially those fitted with engines from MAN. The examples we have in south wales which are fitted with mercedes-benz engoines I have found to be pretty quick off the mark and can do more than 30mph although they do tend to really scream when they get passed 40mph |
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