[net.railroad] combination of third rail and overhead power

cb@mitre-bedford.ARPA (Christopher Byrnes) (01/09/86)

  I believe that the MBTA's Blue Line uses both third rail (in the
tunnel under Boston Harbor) and overhead wire for power.  As I recall,
the reason for this is due to a combination of factors.  The Boston
Harbor tunnel was originally built for streetcars, so its small size
prevents putting a full overhead in the tunnel.  The above ground
section of the Blue Line in East Boston and Revere runs close to the
shoreline, so winter iceing problems forces the need to switch from
third rail to overhead.  It sounds complicated, but it seems to have
worked for the last 30 years.
					Christopher Byrnes
					The MITRE Corporation
					Burlington Road
					M. S. A425
					Bedford, Mass. 01730

					cb@Mitre-Bedford.ARPA
					...decvax!linus!bccvax!cb.UUCP

dennis@CSNET-SH.ARPA (Dennis Rockwell) (01/10/86)

	From: Christopher Byrnes <cb@mitre-bedford.ARPA>
	Date: 09 Jan 86 08:28:54 EST (Thu)
	Subject: Re: combination of third rail and overhead power

	  I believe that the MBTA's Blue Line uses both third rail (in the
	tunnel under Boston Harbor) and overhead wire for power.

Thanks!  I've been wondering why the switch was made.  The four stations in
downtown Boston are third rail, the switch is made at Maverick (in East
Boston, on the other side of the harbor), and the rest of the line north and
eastward (past the airport, the beach, and the racetrack) runs under wire.

Also, Boston's Green Line is essentially a buried (in the denser portions
of the city) streetcar line, now running a few PCC cars (trolley poles) as
well as Boeing LRVs (half-pantographs), the same cars used in parts of San
Francisco.  There is an LRV in the shops with trolley poles that was used
for evaluation.  The other two rapid transit lines (Red and Orange) use
third rail exclusively.  Red, Orange, and Blue lines all use reasonably
normal-looking subway cars, although all three are different (the Red Line
uses two different types itself).

For those interested in arcana, an MBTA employee has restored an old
(wooden!) streetcar and occasionally runs it around the Green Line for
fantrips.  He told me that he sometimes runs it on old street trackage,
using one wire from the trackless trolley overhead!

Dennis

edg@micropro.UUCP (Ed Greenberg) (01/13/86)

In article <1434@brl-tgr.ARPA> dennis@CSNET-SH.ARPA (Dennis Rockwell) writes:
>....  There is an LRV in the shops with trolley poles that was used
>for evaluation.
>Dennis

The book "Inside MUNI" by John McKane and Anthony Perles carries two
interesting pictures from the early days of the Boeing LRV's.  Page 47
carries a picture of "TWO PILOT LRV's nos. 1220 & 1221, arrived in
October 1977 and ran under existing overhead wires with trolley poles
to test components of the cars" Sure enough, there it is, trolley poles
and all.

Page 62 carries a picture of "MUNI REPAIR CAR.  #1088, one of the 1948
double-end PCC's ... was a testbed for the pantographs to be used on
the Boeing-Vertol LRV's and was the first electric car to operate in
the Muni Metro under Market St."  Indeed, two trolley poles (at each
end) and a half-pantograph in the center.

T'is amazing what a car-shop can do if told to do so. :-)
                                -e

--
Ed Greenberg                    | {hplabs,glacier}!well!micropro!edg
MicroPro International Corp.    |  {ucbvax,decwrl}!dual!micropro!edg
San Rafael, California          |       {lll-crg,ptsfa}!micropro!edg