Unidirectional vs Bidirectional

[Myrtone]

I don't know the exact measurements of the curves in the city and suburbs, but the city cars make 90 degree turns from one street into another in a number of places and even the turns inside the subway tunnel are very sharp while the suburban cars do not have a 90 degree turn from one street into another anywhere on the system(this system is overwhelmingly private right of way) The sharpest turn on the suburban system is the loop inside 69th Street Terminal and that is a very gentle turn.

Must be quite a large loop, and is there a station in the loop. Are the stops more widely spaced on the Red Arrow lines than on the "city" lines? And are the "suburban" cars actually interurbans? Are does the Red arrow line not have any street stops? In Prague, the minimum curve radius is techinally 15m, but the on street minimum is 18m, curves less than this being confined to depots. In the photos and videos I have seen, I have not seen any 90 dergee curves at their intersections. This may relate to there 500-600m stop spacing.

The use of trolley poles, I understand, was almost an exclusively North American practice. Modern LRV's are not usually equipped with poles, though the city version of the K-Cars are. In the "old" days, pantographs, were used on some heavier interurban lines, and on heavy mainline railroad electrifications, but were not usually found on city equipment. The suburban K-Cars on the former Red Arrow Lines replaced "conventional" trolley pole equipped equipment, and even the high speed C&LE cars, which were operated at speeds approaching 90 MPH on that system were trolley pole equipped.

They were used in the British Empire as well, and many European systems, including Prague started with trolley poles.

[mtuandrew]

The use of trolley poles, I understand, was almost an exclusively North American practice. Modern LRV's are not usually equipped with poles, though the city version of the K-Cars are. In the "old" days, pantographs, were used on some heavier interurban lines, and on heavy mainline railroad electrifications, but were not usually found on city equipment. The suburban K-Cars on the former Red Arrow Lines replaced "conventional" trolley pole equipped equipment, and even the high speed C&LE cars, which were operated at speeds approaching 90 MPH on that system were trolley pole equipped.

They were used in the British Empire as well, and many European systems, including Prague started with trolley poles.

Moderator's Note: In case anyone would like to continue discussion of the whys and wherefores of trolley poles, pantographs and bow collectors, feel free to check out Trolley v. Pantograph in this same forum.

Interesting topic so far.

[Patrick Boylan]

Must be quite a large loop, and is there a station in the loop.

Yes, in http://www.septa.org/maps/station/69th.html the loop in question is the west terminal. The map's a tiny bit misleading. The trolley loop is the green line in the map, trolleys operate counterclockwise, inbound is a single track, after unloading at the inbound platform, which in the map is between 'Routes 107, 109, 110, 111, the track splits in 2 so the outbound trolley platform, which on the map says Routes 104, 112, 120, 123, and should really have a prefix 101, 102, is between the 2 outbound tracks. Chances are you'll see outbound trolleys only on the map's green line except in weekday evening peak hours. Bus routes 104, 112, 120, 123 use the same space inbound as the trolleys, but outbound stay on the platform's left side. The right side is unpaved, so only the trolleys can use it. The left side, like the inbound platform, is paved, so both buses and trolleys can use it.

One reason why it's a relatively large loop is that bus routes 107, 109, 110, 111 loop clockwise inside the trolley loop.

Are the stops more widely spaced on the Red Arrow lines than on the "city" lines?

Absolutely.

And are the "suburban" cars actually interurbans?

Paraphrasing Bill Clinton, that depends on your definition of interurban. As alluded to before in this thread, they're certainly heavier, generally faster, than SEPTA's city streetcars.

Are does the Red arrow line not have any street stops?

Yes, both lines 101 Media and 102 Sharon Hill have portions of street running with stops, some of which have substantial stone shelters built around 1907. Those stops are a bit further apart than those on most of SEPTA's city trolley lines.

ttp://world.nycsubway.org/us/phila/media-sharon.html photos 41-130 show 69th St and its loop, 21-40 Media street running

You cross Providence Road from Bowling Green and enter State Street, Media's main drag. The single track is dead center in the street and it presents a traffic nightmare, as the street is barely wide enough to have traffic lanes on either side of the tracks. Even this is a tight squeeze and not for the squeamish driver. Your car continues for a little over a half-mile, past the Delaware County Court House, and comes to rest at the end of rail at Orange Street.

photos 161-180 show street running on 102 Sharon Hill line

After crossing Baltimore Pike, your car shortly leaves private right of way for a stretch of street running in Springfield Road. And, almost as quickly, you duck under the R3 Elwyn commuter line (you can duck off the car and board an R3 at Clifton-Aldan station if you'd prefer), then turn off busy Springfield Road into Woodlawn Avenue. The R3 overpass is another favorite photo spot, with good top views of cars available from the station platforms, and possible meets to be photographed.

At the end of street running at North Street, the double track merges into one.

[Myrtone]

One reason why it's a relatively large loop is that bus routes 107, 109, 110, 111 loop clockwise inside the trolley loop.

So the buses entering and leaving the terminal would need to cross somehow.

Are the stops more widely spaced on the Red Arrow lines than on the "city" lines?

What is the stop spaicing on both systems? And are the Red arrow routes all-stoppers? By that I mean, that they stop at all stops whether or not passengrs wish to board or alight. Prague does this with both trams and busses. Do the "city" lines have stops at evey intersection or every second or third?

[walt]

The present configuration of the Red Arrow portion of the 69th Street Terminal dates from 1936 when this portion of the terminal was rebuilt. The original 1907 Terminal was simply a six track stub end affair ( later expanded to eight tracks) with a rather complicated set of switches at the "mouth" of the terminal. ( Thus the original system was completely bi directional) The Red Arrow Lines predecessor Philadelphia & West Chester Traction Company discovered in the late 1920's that loading and unloading cars at the terminal was causing increasing delays, so that portion of the terminal was rebuilt in 1936. Additionally, when the original terminal was built, there were no buses--- this system delevoped in the 1920's. As conceived in 1936, the larger outside loop was exclusively for the trolleys, with the smaller inner loop for buses. When the West Chester trolley line was converted to bus in 1954, the bus replacements continued to use the trolley loop, loading at the one track which is embedded in concrete. The same occurred with the bus replacement for the Ardmore trolley line when that line was converted in 1966.

As I recall, Red Arrow trolleys only stop at stations ( other than 69th Street and the western termini ) if there are passengers wishing to board or alight. Otherwise the cars will run through without stopping. On the P&W ( now SEPTA Route 100) passengers wishing to board at one of the on-line stations were required to set a track signal by pulling a signal cord located in the station, otherwise the extremely fast moving cars would not stop.

[ExCon90]

Route 101 has some rush-hour trips which are designated EXPRESS and skip a number of closer-in stops; any passengers waiting at those stops take a following local. An interesting curiosity some years ago was as far as I know the only "slip carriage" operation on any U. S. traction property. To conserve rush-hour departure slots at 69th St., two St. Louis cars left coupled as a train, the lead car designated express to Springfield (Woodland Ave.), local to Media, the second car express to Scenic Road, local to Springfield. Approaching Scenic Road, the operator of the second car uncoupled using a console switch provided for the purpose and brought his car to a stop at Scenic Road, while the first car went barreling on through Scenic Road, not stopping until Springfield, while the secord car continued to Springfield making local stops. The cars returned separately from Woodland Ave. and Scenic Road, respectively. I don't know how long this lasted.

[ExCon90]

In reponse to Myrtone's question about stops made by city cars, one might build on Gardendance's Clinton analogy and comment that in Philadelphia it depends on what the definition of "intersection" is. Philadelphia has a number of extremely narrow streets (literally one vehicle wide) in between the wider "regular" streets, which in many cities would be regarded as very narrow themselves. By and large, city cars stop at what I have termed "regular" streets, between which there may be two or even three of the one-lane streets, which would be called alleys in many other cities. (But they really are streets, in that there are front doors along them, with house numbers and mailboxes.)

[Myrtone]

I should also note that, while bidirectional rolling stock is almost always configured in a symmetrical way. But unidirectional rolling stock is sometimes configured asymmetrically. An example is the three section Combinos in Erfurt, which have powered front and unpowered rear bogies. Other examples are articulated trams with two bogies under the front and one under the rear section.

[ExCon90]

Some years ago, Milan introduced off-center unidirectional cars with more overhang on the right side than on the left because of limited clearance between tracks in the street. To achieve a wider body they had to put all the increased width on the right side of the vehicle (presumably they counterweighted the cars to compensate for imbalance). No way to do that with bidirectional cars.

[Patrick Boylan]

You must exercise your imagination more. One could do it with bidirectional cars if the clearance problem was on only 1 side, and the cars never looped or wyed, or had skyhook rotate them.

For example the Niagara Gorge Railway usually had plenty of room on the river side, but suppose there was a landslide which caused clearance issues on the cliff side. It might have made more sense for them to put left hand overhang on the cars, instead of doing trackwork to shift the rails away from the cliff.

[Myrtone]

Some years ago, Milan introduced off-center unidirectional cars with more overhang on the right side than on the left because of limited clearance between tracks in the street. To achieve a wider body they had to put all the increased width on the right side of the vehicle (presumably they counterweighted the cars to compensate for imbalance). No way to do that with bidirectional cars.

And this wouldn't be necessary on North American or Australian systems because of wider track centres. Even Prague has never had trams like this as far as I can tell.

Another thing is that party because of the humorous LVT story, it's good practice for physically connected lines within the same city built to the same gauge to conform to the same operational mode, either all lines should be capable of functioning with unidirectional rolling stock or the entire fleet should be bidirectional. While Philadelphia has both balloon loops and unidirectional trollies some lines bidirectional vehicles and dead-end termini on others, there is separation between the the two operational modes, unidirectional looped urban lines and bidirectional on the interurbans. Is there any physical connection between the Red-Arrow and "city" lines?

[Patrick Boylan]

Not in our lifetime.
per Ron Degraw's book The Red Arrow, and probably a bunch of other sources, when originally built in the 1890's the Philadelphia and West Chester Traction Co had a physical track connection with the Philadelphia streetcars at 63rd and Market. That disappeared sometime after 1907 when PWCT, Philadelphia and Western and Philadelphia Rapid Transit all consolidated their operations at their joint 69th St terminal.

I think I remember Rome, Italy, 1976 had some lines with single ended equipment and some with high floor double ended equipment.

[Myrtone]

I know that mixed operationl mode does exist but most of the world's tram systems conform to one operational mode or the other network wide, probably for good operationl reasons. Bidirectional trams can operate anywhere on a network with loops or wyes at both ends of all lines. But on networks with dead end termini, unidirectional trams would either impossible to operate or limited to lines with loops at both ends. By either having all lines capabse of functioning with unidirectional trams or an all bidiectional fleet, there is more scope for diverting routes, the same tram running on different routes on different rosters and moving depots. Potential for charters is also maximized.

[Disney Guy]

The Philadelphia Kawasakis in terms of interurban versus city versions differed in interior layout only. The body shells are the same except for the door arrangement.

From a description of the cars from back in 1981 I believe a Red Arrow Kawasaki will run with no problem on the city lines, with a trolley pole substituted for the pantograph. And a city Kawasaki would negotiate the track with no problems on the Red Arrow lines with a pan substituted for the pole.

[Patrick Boylan]

My understanding is that although both Philly's city and suburban LRV's are the supposed to be the same guage, the suburban ones' track guage is about a quarter inch wider.
Or at least the wheel profiles are different, something like the suburban flanges are deeper, more like railroad flanges, which the city cars have shallower flanges better to fit the in-street track's flangeways.