Low Floor Light Rail Vehicles

[nick]

I've been wondering lately why the T doesn't pursue low-floor light rail vehicles, like those that are common throughout Europe? The Type 8s are half low floor, half high floor, which is fairly awkward, particularly because of the Ts font-door boarding policy. Type 9s seem to double down on this half and half approach, which seems strange to me.

Why wouldn't they go all low-floor? I understand that they have a certain spec they are comfortable with and are using that, but generally what's preventing the T from going fully low floor? Does it have something to do with the tight curves downtown? Are low-floor vehicles more likely to derail? I know the Type 8s had this problem.

 

[winstonoboogie]

I've been wondering lately why the T doesn't pursue low-floor light rail vehicles, like those that are common throughout Europe? The Type 8s are half low floor, half high floor, which is fairly awkward, particularly because of the Ts font-door boarding policy. Type 9s seem to double down on this half and half approach, which seems strange to me.

Why wouldn't they go all low-floor? I understand that they have a certain spec they are comfortable with and are using that, but generally what's preventing the T from going fully low floor? Does it have something to do with the tight curves downtown? Are low-floor vehicles more likely to derail? I know the Type 8s had this problem.

100% low-floor motor trucks need high quality trackage, the Type 8s had issues even with just the non-powered stub-axle equipped center trucks coming off the rail. The design must also be capable of operating at the higher speeds on the Riverside line (42 MPH is high speed for a design intended for street operation)

The other issue is compatibility with existing equipment. Every type of car running in the Green Line subway must have the ability to mechanically couple and push a fully loaded dead train of any car type up the steepest grade on the system. The floor height and anti-climber location of standard 100% low-floor cars is not compatible with the Type 7/8/9 designs. You could try and come up with some sort of compromise design (very high floor height above the couplers, but low floor in the entire passenger cabin) but nothing like that is being built by Bombardier/Alstom/Siemens/Skoda etc and even at that, it would have to fit into 72-feet for a six-axle car because of some of the geometry restrictions in the subway.

 

[Jahvon09]

I've often wondered about that myself.

The design of them more than likely prohibits an all-low-floor layout. Things like the wheels & traction motors are probably taken into consideration.

I believe, just like the Acela train, the cab area where the diver sits pulls the train while the other end pushes it. Note that the floor where the driver sits is slightly raised above the regular floor. That may have a lot to do with it, also.

 

[F-Line to Dudley]

I've often wondered about that myself.

The design of them more than likely prohibits an all-low-floor layout. Things like the wheels & traction motors are probably taken into consideration.

I believe, just like the Acela train, the cab area where the diver sits pulls the train while the other end pushes it. Note that the floor where the driver sits is slightly raised above the regular floor. That may have a lot to do with it, also.

If they could balance a combination of a little bit wider and taller dimensions with fewer tight curves to navigate the articulation with balanced center of gravity, they could do a 100% low-floor design. But that optimal range and balance just doesn't exist here. The Central Subway is too permanently scrunched on all sides with geometry that's too hard to modify, so the cars are too dimensionally pinched to hit an all-low design target that'll perform with any reliability.

Even Toronto, whose svelte CLRV streetcars were evaluated in unmodified form in revenue service on the Green Line 35 years ago as a potential buy before the T opted for the Type 7's instead, had to increase its all-around car dimensions appreciably in order to do 100% low-floor with its ongoing Bombardier Flexity order. Not every legacy system has enough fractions of an inch left to give to do that. The Green Line has literally zero since the last 3 post-PCC purchases maxed out every nook of clearance the oldest tunnels had left to give. The craptacular-design Breda center trucks that were the source of all the years of derailments can--and will--be substantially improved in the Type 9 order. But some facsimile of that car config is the best they'll be able to do on all foreseeable future orders.

 

[Jahvon09]

If they could balance a combination of a little bit wider and taller dimensions with fewer tight curves to navigate the articulation with balanced center of gravity, they could do a 100% low-floor design. But that optimal range and balance just doesn't exist here. The Central Subway is too permanently scrunched on all sides with geometry that's too hard to modify, so the cars are too dimensionally pinched to hit an all-low design target that'll perform with any reliability.

Even Toronto, whose svelte CLRV streetcars were evaluated in unmodified form in revenue service on the Green Line 35 years ago as a potential buy before the T opted for the Type 7's instead, had to increase its all-around car dimensions appreciably in order to do 100% low-floor with its ongoing Bombardier Flexity order. Not every legacy system has enough fractions of an inch left to give to do that. The Green Line has literally zero since the last 3 post-PCC purchases maxed out every nook of clearance the oldest tunnels had left to give. The craptacular-design Breda center trucks that were the source of all the years of derailments can--and will--be substantially improved in the Type 9 order. But some facsimile of that car config is the best they'll be able to do on all foreseeable future orders.

It would also probably cost more to have that done, and the T is more than likely going to stick with the regular floor plan for them.