Unidirectional vs Bidirectional

General discussion of passenger rail proposals and systems not otherwise covered in the specific forums in this category, including high speed rail.

Moderators: gprimr1, mtuandrew

Unidirectional vs Bidirectional

Postby Myrtone » Sat Sep 25, 2010 7:41 pm

An operational question for North Americans. In an edition of Transit Australia from last year there was an article by Tony Prescott where he argues for unidirectional running, he has this idea of tram going only one way, with a driver's cab at only the front, doors on only one side and using loop track to turn around. His article is about why some European systems stick to unidirectional running and why many newcomers to LRT are so reluctant to consider it.
I have noticed that the Portland streetcar line is basically a single track loop, with streetcars running continuously in the same direction. Yet their rolling stock is all designed for bidirectional running, because they started with dead end termini. There is some discussion on skyscraper city. A poster from Syndey, New South Wales, Australia wanted to know whether Czech tram operators have had any significant problems with operating unidirectional trams and what the experience was like over the years. Someone else replied that bidirectional system were not considered necessary and there were not siginificant problems. Larger systems like Prague have small bidirectional fleets which can be used on lines temporarily truncated for trackwork, and others couple unidirectional trams back to back.

As for US streetcar operations, knowing that Boston and Philadelphia use unidirectional LRVs quite extensively. Have cities like Philidelphia ever considered switching to bidirectional running or are they happy with the way things are? Unidirectional running was historically common in North America and did all those old systems run into significant problems.

If you have a driver's cab at only the front and doors on only the right, there will be more seats and most fixed front facing. Here in Australia, according to that aforementioned Australian poster on skyscraper city, many public transport users also do not like facing each other, so Sydney trains often have flip over seating, but trams here in Melbourne and those of the Sydney light rail, and all new trams in Adelaide have half the seats facing each way. Some old trams here, such as the Adelaide H class and the Y class Melbourne tram had flip over seats. Is there is same problem in North America with traveling backwards, and do reversible seats have any history in North America?

A case that comes to mind is Washington DC, it appears that their new system will use bidirectional trams and dead end termini despite the fact that their previous system, many surviving unidirectional networks show no signs of converting to bidirectional running, and the supplier, Skoda, supplies mostly unidirectional rolling stock. Does Washington have any island platforms or is it side platforms only? Note that staggered side platforms can take up less lateral space than island platforms, and on narrower roads, stops are necessarily on the kerbside.
And even if you operate bidirectional rolling stock, you may need loops at busy termini because there is often not enough time to change ends, and even if there is only just enough, what happens if the driver discovers a hidden fault.
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby gt7348b » Sun Sep 26, 2010 10:27 am

Just one correction - Boston has unidirectional running only on the Mattapan High Speed Line. All the Green Line trains need Bi-Directional because both sets of doors open at Park Street, Government Center is an island platform, and those trains that run through North Station also require bi-directional rolling stock to allow the doors to open correctly to face the platform.

FWIW, I know here in Atlanta while the proposed streetcar is essentially a loop and could probably accommodate unidirectional running, I think it was the ROW requirements for the turnaround loop that caused the design for bi-directional vehicles.
Atlanta - within two and a half hours of . . . the edge of its suburbs
gt7348b
 
Posts: 221
Joined: Sat Jan 29, 2005 5:10 pm
Location: Atlanta

Re: Unidirectional vs Bidirectional

Postby Myrtone » Sun Sep 26, 2010 6:36 pm

gt7348 wrote:Boston has unidirectional running only on the Mattapan High Speed Line. All the Green Line trains need Bi-Directional because both sets of doors open at Park Street, Government Center is an island platform, and those trains that run through North Station also require bi-directional rolling stock to allow the doors to open correctly to face the platform.


Actually, don't all rolling stock, whether unis or bis need doors on both sides because of island platforms. Wouldn't the actual reason have to with changing direction at termini?

Moderator's Note: duplicate post deleted, 10:12 PM CDT 9/26/10
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby ExCon90 » Sun Sep 26, 2010 7:21 pm

As far as I know, the only bidirectional PCCs Boston ever had were the ones they bought from Dallas to use on such trips as the Northeastern University turnbacks which used intermediate crossovers. The PCCs simply had one additional door on the left side--no need for bi-directional running.
ExCon90
 
Posts: 3936
Joined: Thu Sep 18, 2008 1:22 pm

Re: Unidirectional vs Bidirectional

Postby typesix » Tue Sep 28, 2010 10:44 am

Only the new North Station under terminal on the MBTA requires bidirectional cars, all other terminals can run unidirectional cars.
typesix
 
Posts: 648
Joined: Fri Mar 12, 2004 11:23 am
Location: Boston

Re: Unidirectional vs Bidirectional

Postby wigwagfan » Tue Sep 28, 2010 10:47 am

Myrtone wrote:I have noticed that the Portland streetcar line is basically a single track loop, with streetcars running continuously in the same direction. Yet their rolling stock is all designed for bidirectional running, because they started with dead end termini.

Egh, not quite. Yes, in the beginning the Portland Streetcar had that ridiculous stub end track on S.W. Montgomery Street but that was never intended to be permanent. That was actually more of a design flaw resulting from a decision to push the Streetcar onto the PSU campus; the original plan for the Streetcar was for it to be an actual loop ending at S.W. Market Street and turning back onto 10th Avenue. (In retrospect, the Streetcar could have simply continued on the 11th Avenue pedestrian esplanade south to Harrison, and then looping back onto 10th - thus providing direct on-campus PSU access, while retaining a loop configuration. However the powers-that-be wanted to create the Urban Center with the Streetcar running through it.) Then the Streetcar pushed further to S.W. Moody Avenue - again, not a permanent arrangement; then again to S.W. Gibbs Street; now it is finally a loop terminating at S.W. Lowell Street. As a result, the Streetcar was more of a "U" shape because the N.W. 23rd Avenue end of the run was always a loop.

MAX is operated a bit differently. The real estate needed for a MAX turning loop is much greater (for example an entire city block is taken up by the turning loop at the south end of the mall; and half a block is required for the old 11th Avenue terminus). A train running from Gresham to Hillsboro takes 1 hour 40 minutes to complete the run; afterwhich the Operator takes a break. A stub-end terminal station makes the most use of costly real estate, allows the station platform to have a simple design (curved station platforms are always difficult to engineer) and does not add to operational inefficiencies.

TriMet does have some cars with only one cab - the type 4 trains. However, they are always operated with another type 4 car, so the result is a bi-directional train. The added seating capacity - which I refer to as the "parlour" or "observation" area, has eight seats in it that would otherwise not be there. But due to reduced seating in the mid-section of the car between the doors, the end result is that a Type 4 car has just four more seats than a Type 2 or 3 car, and six fewer seats than a Type 1 car. I've also found that the seating area tends to not be popular with many folks (and thus I always tend to sit there).
--------------------------------------------------
Erik Halstead - Portland, Oregon
User avatar
wigwagfan
 
Posts: 3291
Joined: Mon Feb 28, 2005 10:57 am
Location: Portland, Oregon

Re: Unidirectional vs Bidirectional

Postby Myrtone » Wed Sep 29, 2010 8:40 pm

wigwagfan wrote:Egh, not quite. Yes, in the beginning the Portland Streetcar had that ridiculous stub end track on S.W. Montgomery Street but that was never intended to be permanent. That was actually more of a design flaw resulting from a decision to push the Streetcar onto the PSU campus; the original plan for the Streetcar was for it to be an actual loop ending at S.W. Market Street and turning back onto 10th Avenue. (In retrospect, the Streetcar could have simply continued on the 11th Avenue pedestrian esplanade south to Harrison, and then looping back onto 10th - thus providing direct on-campus PSU access, while retaining a loop configuration. However the powers-that-be wanted to create the Urban Center with the Streetcar running through it.) Then the Streetcar pushed further to S.W. Moody Avenue - again, not a permanent arrangement; then again to S.W. Gibbs Street; now it is finally a loop terminating at S.W. Lowell Street. As a result, the Streetcar was more of a "U" shape because the N.W. 23rd Avenue end of the run was always a loop.


I wasn't quite sure but know from another discussion that it wasn't always a loop.

wigwagfan wrote:MAX is operated a bit differently. The real estate needed for a MAX turning loop is much greater (for example an entire city block is taken up by the turning loop at the south end of the mall; and half a block is required for the old 11th Avenue terminus). A train running from Gresham to Hillsboro takes 1 hour 40 minutes to complete the run; afterwhich the Operator takes a break. A stub-end terminal station makes the most use of costly real estate, allows the station platform to have a simple design (curved station platforms are always difficult to engineer) and does not add to operational inefficiencies.


I don't know what the minimum curve radius for the MAX is but I know the standard LRT minimum is 25 metres. The stub-end terminal station is obviously less busy than the other end so of course the stub does not add operational inefficiencies. Also the trains I have seen in photos are longer than a street running tram, which means more seats while having driver controls at both ends and doors on both sides. The traditional tramway minimum is 15 metres, which means that loops can take up less space. In addition to being shorter, trams often run at closer headways on busier parts of a network, meaning there is less time for changing ends.
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby wigwagfan » Mon Oct 04, 2010 12:16 pm

Myrtone wrote:The traditional tramway minimum is 15 metres, which means that loops can take up less space. In addition to being shorter, trams often run at closer headways on busier parts of a network, meaning there is less time for changing ends.

I work near the South Mall MAX terminus and frequently watch trains make their turnaround there.

Given that trains must move at a crawling pace through the excessively sharp curve to make the turnaround, it would not take any more time for a stub-end terminal to have been built, and the Operator simply walk the 140 feet or so to change ends, and then go - takes about two minutes.

In terms of real estate, a stub track (just like the old Streetcar stub on Montgomery) could have been built in the unused area of the 5th Avenue overpass over I-405; and then a switch and then the lead to 6th Avenue would be where the current equipment shack is. Far less real estate, same function, lower cost, no operational inefficiency.

If you look at the Streetcar loop's north end on 23rd Avenue, what you make convenient for the Streetcar poses huge problems for motor vehicle, bicycle and pedestrian traffic in the area - cars have to be held back to allow room for the Streetcar to turn; traffic lights have to be specially timed; pedestrians are held up because of longer "don't walk" signals and you have curved rails in the intersection posing a hazard to bicyclists (which is a HUGE deal in both Portland and Seattle.)
--------------------------------------------------
Erik Halstead - Portland, Oregon
User avatar
wigwagfan
 
Posts: 3291
Joined: Mon Feb 28, 2005 10:57 am
Location: Portland, Oregon

Re: Unidirectional vs Bidirectional

Postby Myrtone » Tue Oct 05, 2010 3:22 am

wigwagfan wrote:I work near the South Mall MAX terminus and frequently watch trains make their turnaround there.


Is there a video available online showing this.

wigwagfan wrote:Given that trains must move at a crawling pace through the excessively sharp curve to make the turnaround, it would not take any more time for a stub-end terminal to have been built, and the Operator simply walk the 140 feet or so to change ends, and then go - takes about two minutes.


Consider how long the trains are, and that the high floor rolling stock has only two sections, there is a pivoting bogie under each end and a bogie under the articulation, while the low floor rolling stock has two long sections, each with a pivoting bogie under the outer end, and a very short centre section on a fixed bogie. An on-street tram of similar length would also have three sections but more alike in length and with a bogie under each articulation as well as a pivoting bogie under each end. Thus an on street tram would loop around faster.

wigwagfan wrote:In terms of real estate, a stub track (just like the old Streetcar stub on Montgomery) could have been built in the unused area of the 5th Avenue overpass over I-405; and then a switch and then the lead to 6th Avenue would be where the current equipment shack is. Far less real estate, same function, lower cost, no operational inefficiency.


These tracks are for MAX, not for unidirectionl trams.
Real estate: A loop may be around a block, in which case route can be incorperated into the loop, for example, if one or more lines serve thi city square, the loop circle the square with stops on the loop.
Function: Not the same, loops are compadible with unidirectional rolling stock, which are cheaper than bidirectional rolling stock, and carry more passegers in shorter length.

wigwagfan wrote:If you look at the Streetcar loop's north end on 23rd Avenue, what you make convenient for the Streetcar poses huge problems for motor vehicle, bicycle and pedestrian traffic in the area - cars have to be held back to allow room for the Streetcar to turn; traffic lights have to be specially timed; pedestrians are held up because of longer "don't walk" signals and you have curved rails in the intersection posing a hazard to bicyclists (which is a HUGE deal in both Portland and Seattle.)


The problem here is obviously curve radius. This wousd be less or a problem with pivoting bogie (low floor) trams because they can negotiate tighter curves and so less room is needed for them to turn.
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby walt » Sat Oct 09, 2010 10:21 pm

Myrtone wrote:
As for US streetcar operations, knowing that Boston and Philadelphia use unidirectional LRVs quite extensively. Have cities like Philidelphia ever considered switching to bidirectional running or are they happy with the way things are? Unidirectional running was historically common in North America and did all those old systems run into significant problems.


Philadelphia has both. The remaining city streetcar lines, the five West Philadelphia subway surface lines and the all surface Route 15 are "unidirectional" while the two remaining former Red Arrow Lines suburban trolley lines and Route 100, the former Philadelphia & Western Railroad ( Interurban known as the P&W) are "bidirectional". Since all of these lines could be described as "heritage" lines, in that they were built in the "early days" of US electric traction, the factors which determined whether they would be unidirectional or bi directional would be factors which existed in that earlier period, now 100 years in the past. The major factor would have been cost, since these were privately built and privately financed lines. Generally, the unidirectional line, which would employ cars, described here in the US, as "single ended" was more expensive to construct, because of the cost of acquiring land for, and building, turning loops at each end though the cars themselves were less costly because they only had "one end" ie. one control platform. Sometimes, single ended cars were turned using a track configuration known as a "Wye" which allowed a car to be turned using a somewhat complicated backing maneuver, but the vast majority of streetcar lines using single ended equipment used turning loops wherever cars were to reverse direction. This became the preferred type of line, and many formerly stub end ( bidirectional) lines were converted once sufficient land was acquired for the construction of a loop. Double Ended Cars were initially more expensive to acquire, because of the cost of the second control platform, though the lines themselves were often less expensive to construct. The major consideration here, though was the unavailability of sufficient land to construct a loop. The Red Arrow trolley lines ( there were four originally---- only two remain today) looped, after 1936, at their common Terminus in the 69th Street Terminal. but simply reversed ends at their outbound ends, two of which were simply "end of track" in the middle of a street. The Red Arrow ( conventional) cars had "walkover seats" which could be reversed as the car reversed direction. The present LRV's have seats on one side of the car facing in one direction, and seats on the opposite side facing in the opposite direction.

I think one reason why modern LRV's are mostly double ended is the extensive use of "train" operation. Very few, if any, single ended streetcars were Multi Unit, and thus, could not be operated as anything other than single units. In the early days, there was some use of unpowered trailers behind single ended equipment, but generally, US streecars ran as single units. Suburban and Interurban applications, such as the Red Arrow Lines, on the other hand, often operated multi car "units" which almost always consisted of Multi Unit double ended cars.

There is an interesing historical note in all of this. Between 1949 and 1951, the Lehigh Valley Transit Co. (LVT) operated single ended high speed interurban cars between Norristown Pa. and Allentown over what was known as its Liberty Bell Route. ( prior to 1949, Liberty Bell Route Cars had operated all the way to 69th Street, using the P&W tracks between Norristown and 69th Street) the Norristown Terminus was at a single track, second story elevated station owned by the P&W. The LVT cars, being single ended, could not be turned at that station so, once a southbound car had detrained its passengers, it was backed out of the station, through the streets of Norristown to a freight station with outside yard tracks where the cars were "Wyed" ( turned) and then run, still backwards, back to the station where they could then pick up northbound passengers for the run back to Allentown. The LVT might have considered buying double ended cars, but the entire Liberty Bell Route, as well as the LVT itself, was abandoned in 1951.
Please Move to the Rear and Speed Your Ride
( Philadelphia Transportation Company)
walt
 
Posts: 1089
Joined: Mon Mar 15, 2004 4:51 pm
Location: Columbia, MD

Re: Unidirectional vs Bidirectional

Postby Myrtone » Sat Oct 09, 2010 11:46 pm

walt wrote:Philadelphia has both. The remaining city streetcar lines, the five West Philadelphia subway surface lines and the all surface Route 15 are "unidirectional" while the two remaining former Red Arrow Lines suburban trolley lines and Route 100, the former Philadelphia & Western Railroad ( Interurban known as the P&W) are "bidirectional".


Unidirectional running is more advantageous in street transit than on interurban lines. Do the Red arrow lines have a wider minimum curve radius than the Western subway-surface lines?

walt wrote:Since all of these lines could be described as "heritage" lines, in that they were built in the "early days" of US electric traction, the factors which determined whether they would be unidirectional or bi directional would be factors which existed in that earlier period, now 100 years in the past.


Wouldn't they be better described as legacy lines? And some of these factors still apply today as evident from the fact that many surviving unidirectional tramway networks show no signs of converting to bidirectional running.

walt wrote:The major factor would have been cost, since these were privately built and privately financed lines. Generally, the unidirectional line, which would employ cars, described here in the US, as "single ended" was more expensive to construct, because of the cost of acquiring land for, and building, turning loops at each end though the cars themselves were less costly because they only had "one end" ie. one control platform. Sometimes, single ended cars were turned using a track configuration known as a "Wye" which allowed a car to be turned using a somewhat complicated backing maneuver, but the vast majority of streetcar lines using single ended equipment used turning loops wherever cars were to reverse direction. This became the preferred type of line, and many formerly stub end ( bidirectional) lines were converted once sufficient land was acquired for the construction of a loop.


A loop may be around a block, or simply a balloon loop. If it is round a block, some route can be incorporated into the track and passengers can be served this way.

walt wrote:Double Ended Cars were initially more expensive to acquire, because of the cost of the second control platform, though the lines themselves were often less expensive to construct. The major consideration here, though was the unavailability of sufficient land to construct a loop. The Red Arrow trolley lines ( there were four originally---- only two remain today) looped, after 1936, at their common Terminus in the 69th Street Terminal. but simply reversed ends at their outbound ends, two of which were simply "end of track" in the middle of a street. The Red Arrow ( conventional) cars had "walkover seats" which could be reversed as the car reversed direction. The present LRV's have seats on one side of the car facing in one direction, and seats on the opposite side facing in the opposite direction.


Bidirectional rolling stock always requires a second cab and full set of controls as well as doors on both sides, simple no brainer. Unidirectional rolling stock only has one drivers cab and full set of controls, and may only need doors on one side. Were reversible phased out for safety reasons.

walt wrote:I think one reason why modern LRV's are mostly double ended is the extensive use of "train" operation. Very few, if any, single ended streetcars were Multi Unit, and thus, could not be operated as anything other than single units. In the early days, there was some use of unpowered trailers behind single ended equipment, but generally, US streecars ran as single units. Suburban and Interurban applications, such as the Red Arrow Lines, on the other hand, often operated multi car "units" which almost always consisted of Multi Unit double ended cars.


Unpowered trailers are one reason why unidirectional running came about initially, to avoid inconvenient and possibly dangerous shunting at termini. Of course multiple unit operation is possible with unidirectional trams. In fact there are two types of multiple unit operation with unidirectional running. One type is used when running coupled trams in normal service, where both are facing the same way, this is common in European cities such as Riga. The other type is back to back operation, where the trams are back-to-back coupled, for lines temporarily truncated for trackwork. With singled sided trams, only the lead vehicle takes passengers.

Image

Has this ever been practiced in North America? And did any North American unidirectional systems have small bidirectional fleets used on such lines.

walt wrote:There is an interesing historical note in all of this. Between 1949 and 1951, the Lehigh Valley Transit Co. (LVT) operated single ended high speed interurban cars between Norristown Pa. and Allentown over what was known as its Liberty Bell Route. ( prior to 1949, Liberty Bell Route Cars had operated all the way to 69th Street, using the P&W tracks between Norristown and 69th Street) the Norristown Terminus was at a single track, second story elevated station owned by the P&W. The LVT cars, being single ended, could not be turned at that station so, once a southbound car had detrained its passengers, it was backed out of the station, through the streets of Norristown to a freight station with outside yard tracks where the cars were "Wyed" ( turned) and then run, still backwards, back to the station where they could then pick up northbound passengers for the run back to Allentown. The LVT might have considered buying double ended cars, but the entire Liberty Bell Route, as well as the LVT itself, was abandoned in 1951.


Did the LVT cars have basic controls at the rear (not uncommon on unidirectional rail vehicles) that were used for reversing?
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby Patrick Boylan » Sun Oct 10, 2010 6:53 am

According to Ron Degraw's The Red Arrow book LVT regular service before truncating to Norristown 1949 also backed out of 69th St terminal and used a wye near 72nd St. I'm assuming they built this wye specifically to reverse LVT single ended cars, as opposed to the Norristown, where they took advantage of the existing freight station's wye, which was quite some distance from the Norristown terminal. Maybe more than a mile of up and downhill street running?
I can't pinpoint where I heard it over the years but my understanding is yes, the the single ended cars LVT used after 1940 did have rudimentary backup controls. I imagine so would have the single ended equipment LVT used before the 1940's.
So LVT, and the Cincinnati and Lake Erie Railroad from which they bought the 1940's cars are exceptions to the idea that interurban historic or legacy lines were double ended. Other exceptions I can think of are New York's Fonda, Johnstown and Gloversville, and Utah's Bamberger, which bought their single ended cars when FJ&G abandoned rail.

I'm pretty sure the only backup controls on Philly trolleys were http://www.phillytrolley.org/usedcar/ph ... yused.html the 40 ex Kansas City PCC's. I assume the 11 more ex-Kansas City cars from Toronto in 1976 would have the same equipment as the first batch of 40 second hand PCC's.
Certainly Philly's 1920's vintage Peter Witt single enders that I've seen in museums had no backup controls.

Time marches sideways, and the 112 Kawasaki cars which replaced the PCC's have backup controls. At least one of SEPTA's trolleyfests, 1993, at Elmwood depot, allowed the public to operate a Kawasaki car, both directions on a short stretch of yard track, using the backup controls. That weekend the Buckingham Valley Trolley Association also offered general public 'be the motorman' rides on double ended Brill Master Unit 80 at Penn's Landing.

The backup controls on single ended equipment that I've seen had at most 3 levers: power; brake; direction.

http://web.presby.edu/~jtbell/transit/FtWorth/
Fort Worth's Leonard's M&O department store, subsequently Tandy, subway used second hand Washington DC single ended PCC's. When I rode it in the early 1990's they had converted them to high platform double ended air conditioned cars. They used cables to connect the new extra operating controls to the original, so you'd get to see, or not see, a ghost operator depress the reverser, power and brake pedals as the living motorman did his job at the other end.
User avatar
Patrick Boylan
 
Posts: 3432
Joined: Mon Sep 01, 2008 1:44 pm
Location: Here is a stupid picture, pay attention to me. Burlington Township, NJ 08016

Re: Unidirectional vs Bidirectional

Postby walt » Sun Oct 10, 2010 8:20 am

Almost anything that is said about traction operations in North America will have exceptions, as is evidenced by the comments posted above. The use of the term "heritage' is simply the term used by most of the operators of that type of line, "legacy" would work just as well. The Red Arrow cars were longer than the Philadelphia city cars, and the turns on the Red Arrow system were not nearly as tight as in the city. Likewise the Kawasaki LRV's now being used on the former Red Arrow Lines are longer than their city sisters.

The C&LE, from whom the LVT bought the 1000 series cars used after 1938 was somewhat unique in that its passenger runs originated and terminated at rather large interurban terminals which dated from the Ohio Electric days in the 1910's and 1920's. Cars were able to run through these stations, which created rather long loops, so the C&LE was able to use single ended passenger equipment.

Whether or not single ended cars had auxiliary controls in the rear simply reflected the choice of the company which purchased the cars. As I recall, Philadlephia did not use rear controls, while Baltimore did. I don't know whether the LVT cars had rear controls, though the LVT did install a trolley pole on the front end of the cars, which the cars did not have on the C&LE.

I suspect that the primary reason that "walkover" seats were not used on the suburban Kawasaki LRV's is cost- the current seating is cheaper than a walkover seat would be----- if they are still being manufactured. However another factor may be the fact that the K-Cars use pantographs rather than trolley poles, thus eliminating a procedure that operators used to have to employ when reversing direction. The old procedure was that the operator would exit the car, raise the pole on what was the front end, then lower the pole at the opposite end, and then would walk through the car "walking" the seat backs over to face the seats in the opposite direction. With the elimination of the trolley pole and the use of the current seating arraingement, reversing direction only requires the operator to walk to the opposite platform and controls to operate the car from that end. Much less interesting to watch, but much easier on the operator.
Please Move to the Rear and Speed Your Ride
( Philadelphia Transportation Company)
walt
 
Posts: 1089
Joined: Mon Mar 15, 2004 4:51 pm
Location: Columbia, MD

Re: Unidirectional vs Bidirectional

Postby Myrtone » Sun Oct 10, 2010 9:26 am

walt wrote:The Red Arrow cars were longer than the Philadelphia city cars, and the turns on the Red Arrow system were not nearly as tight as in the city. Likewise the Kawasaki LRV's now being used on the former Red Arrow Lines are longer than their city sisters.


The greater length means more seats while have a cab at both ends and doors on both sides. I read the curves on the 'city' part are as tight as 10m, similar to Toronto's 11m. Is the minimum on the 'Red Arrow' lines similar to the standard LRT minimum of 25m?

walt wrote:I suspect that the primary reason that "walkover" seats were not used on the suburban Kawasaki LRV's is cost- the current seating is cheaper than a walkover seat would be----- if they are still being manufactured.


Are you saying that modern safety regulations add to the cost of reversible seating? I get the impression that Philadelphians prefer to travel forwards and this, combined with safety regulations is another reason why unidirectional trams are cheaper.

walt wrote:However another factor may be the fact that the K-Cars use pantographs rather than trolley poles, thus eliminating a procedure that operators used to have to employ when reversing direction. The old procedure was that the operator would exit the car, raise the pole on what was the front end, then lower the pole at the opposite end, and then would walk through the car "walking" the seat backs over to face the seats in the opposite direction. With the elimination of the trolley pole and the use of the current seating arraingement, reversing direction only requires the operator to walk to the opposite platform and controls to operate the car from that end. Much less interesting to watch, but much easier on the operator.


Nearly all European tramways unidirectional or bi use pantographs, and many, such as those in Prague and Vienna, have front mounted pantos. Not only that but the bidirectional KT8s in Prague have pantographs at both ends.
Also known as Myrtonos
Myrtone
 
Posts: 205
Joined: Sat Sep 25, 2010 6:11 pm

Re: Unidirectional vs Bidirectional

Postby walt » Sun Oct 10, 2010 10:21 am

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.

With regard to the seating, I am not aware that safety comparisons were a major factor in the change from walkover seating to the present arraingement. Others may have better information in that regard than I do. Fixed direction seating is less costly than walkover seating, or the alternative swivel type seating that some railroad cars ( including the Electroliner- Liberty Liner train sets that operated over the P&W for a period in the late 1960's early 1970's) employed. Given the circumstances under which both editions of the K-Cars were purchased ( their acquisition was "hastened" by a major carbarn fire in 1978 which destroyed many of the PCC cars which operated on the subway surface lines, causing SEPTA to have to scramble to find replacement cars in order to keep the subway surface lines operating) I suspect that cost was the major factor here.

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.
Please Move to the Rear and Speed Your Ride
( Philadelphia Transportation Company)
walt
 
Posts: 1089
Joined: Mon Mar 15, 2004 4:51 pm
Location: Columbia, MD

Next

Return to General Discussion - Passenger Rail

Who is online

Users browsing this forum: No registered users and 2 guests