On Thu, 22 Dec 2005, Richard J. wrote:

But at least they could divert, which trams and trolley buses would not
be able to do.

Take a look at (apologies for the horrible URLs) some of the fleet
listed at
http://www.tpg.ch/Internet+TPG/Franc...cVehicules.htm
for example
http://www.tpg.ch/Internet%20TPG/Fra...HESSBBC-SE.htm

GMA (Groupe de marche autonome)
Moteur essence VW / 127

I read that as something like
"autonomous propulsion group / petrol motor", no?

I don't know whether this feature is ever used for rescues in
passenger service, but evidently these trolleybuses are capable of
moving themselves if/when the need arises. (Not all of them are shown
as fitted with this feature, in case you want to have a whine.)

To the best of my recollection, some German trolleybuses have (or have
had) a fully fledged diesel motor, used routinely on the outer parts
of their routes, and only switch to/from OHL power for the more
central parts of the town/city. Evidently, in the event of a problem
(road blockage, OHL or power failure) they would be capable of
continuing in service on the other power source.

"Alan J. Flavell" wrote:

To the best of my recollection, some German trolleybuses have (or have
had) a fully fledged diesel motor, used routinely on the outer parts
of their routes, and only switch to/from OHL power for the more
central parts of the town/city. Evidently, in the event of a problem
(road blockage, OHL or power failure) they would be capable of
continuing in service on the other power source.

As do some in the US - Seattle among other cities use them. Interestingly
enough, it appears that they are being phased out though. Note the last
paragraph:

Planned rebuilding of articulated trolley buses: The dual-powered
(electric-diesel) articulated buses that go through Seattle's bus tunnel are
reaching the end of their useful lives. Metro plans to rebuild them as
electric-only articulated trolley buses and bring them into service in 2004-2005
on high-ridership routes 7, 43, and 44.

http://transit.metrokc.gov/up/archiv...4-trolley.html

On Thu, 22 Dec 2005 22:43:42 -0700, Clark W. Griswold, Jr. wrote:

"Alan J. Flavell" wrote:
Evidently, in the event of a problem
(road blockage, OHL or power failure) they would be capable of
continuing in service on the other power source.

As do some in the US - Seattle among other cities use them. Interestingly
enough, it appears that they are being phased out though. Note the last
paragraph:


Metro plans to rebuild them as
electric-only articulated trolley buses and bring them into service in 2004-2005
on high-ridership routes 7, 43, and 44.

http://transit.metrokc.gov/up/archiv...4-trolley.html

I bet they have traction batteries though - the weight of the diesel
engine and the fuel tank would hold quite a lot of battery power.


The new Roma (Italy) Route 90 trolley buses actually run the into the
city centre on battery - the wires stop at the old city wall. They stop,
drop their poles and drive in on battery.

The lights dim slightly, the air-conditioning stops, and the bus can't
accelerate as hard when the poles are dropped, but they are quite capable
of moving with the traffic at that point.

"Alan J. Flavell" wrote:

To the best of my recollection, some German trolleybuses have (or have
had) a fully fledged diesel motor, used routinely on the outer parts
of their routes, and only switch to/from OHL power for the more
central parts of the town/city.

There's an interesting video here

mms://winmedia.metrokc.gov/transit/ITtunnel.wmv

It shows dual operating buses and some other detaiils.

On Fri, 23 Dec 2005 00:26:51 +0000, "Alan J. Flavell"
wrote:

To the best of my recollection, some German trolleybuses have (or have
had) a fully fledged diesel motor, used routinely on the outer parts
of their routes, and only switch to/from OHL power for the more
central parts of the town/city. Evidently, in the event of a problem
(road blockage, OHL or power failure) they would be capable of
continuing in service on the other power source.

Seattle's system does this, running as trolley buses underground
through the city centre, and using diesel once on the surface. They
are articulated but I don't know who made them.
--
Terry Harper
Website Coordinator, The Omnibus Society
http://www.omnibussoc.org

Terry Harper wrote:

Seattle's system does this, running as trolley buses underground
through the city centre, and using diesel once on the surface. They
are articulated but I don't know who made them.

The Seattle dual power buses were made by Breda of Italy, but they are being
phased out due to maintenance and parts availability issues. Apparently, there
were only just over 200 made and they shared a similar heritage to Fiat cars
("Fix It Again, Tony").

The Seattle bus tunnel is currently closed for renovation for 2 years, and the
metro bus authority is taking the opportunity to replace the Bredas with deisel
electric hybird buses that cost $200,000 more than standard deisels and get less
than 4 miles per gallon.