PAT route changes in March (Pittsburgh, Wilkinsburg: safety, train, vehicles)

[Blackbeauty212]

So are you going to provide that link of the system that replicates what you state is fact. I'm not being a smart ***....I'm truly interested in this.

I done some digging online and i still cannot find a so-called system that have trains with this kind of technology in America that allows for Rapid speed at sharp curves and bends.

You don't think there will be a slowing of service, take a trip on the South Busway where the T share road way with buses, and count the traffic lights at the on and off ramps, also tell me what happens when a buses need to merger onto that portion of the busway...Then take that a duplicate it on the East Busway were you have ton more services using the East Busway vs the South......You will infact slow service!

[ctoocheck]

Originally Posted by Blackbeauty212

So are you going to provide that link of the system that replicates what you state is fact.

Me? I'm currently in Dresden. The transit provider is the Dresdner Verkehrsbetriebe. I don't think you'll find any relevant info on their website, but two of the spots I can think of off the top of my head are at Schloßplatz (in the city center) and right near the Mordgrundbrücke stop to the northeast of the city on line 11, near the intersection of Bautzner Straße and Schillerstraße. Of course there's no way for you to check how fast they're actually going. Also the bend under the Bloomfield bridge doesn't seem that sharp (700' radius), so... I mean, the entire ROW was originally (and still is) a proper heavy rail line! If freight trains can handle it, I'm sure LRT could.


I've never been on the South Busway so I can't comment on that. The two only share a tiny stretch though. Maybe it could have something to do with switching for the LRVs? Does it even really have to do with the light rail at all? I don't know.

Like I said, converting the East Busway to LR doesn't seem to a unanimously popular an idea and would probably not happen anyway, so...

[BrianTH]

So I'm trying to do some math. I think the buses are doing that 700-feet radius turn at around 40 mph, which by my math works out to a radial acceleration of just under 5 f/s2, or about 0.15 Gs.

Can T-style light rail systems handle that sort of radial acceleration? That seems to be the question.

[Blackbeauty212]

Next time you ride the East Busway and you see how fast those buses cut those curves and bends ask your self do you really see a rail car replicating these same speeds around these bends...

Its not possible, and if there is technology the Port Authority probably would have to buy all new LRV's because the current fleet is not capable...

[ctoocheck]

Originally Posted by Blackbeauty212

Next time you ride the East Busway and you see how fast those buses cut those curves and bends ask your self do you really see a rail car replicating these same speeds around these bends...

Its not possible, and if there is technology the Port Authority probably would have to buy all new LRV's because the current fleet is not capable...

Are you some sort of scientist? I'm sorry, but this just sounds silly.

[BrianTH]

Originally Posted by Blackbeauty212

Its not possible, and if there is technology the Port Authority probably would have to buy all new LRV's because the current fleet is not capable...

I honestly don't have a dog in this fight, but it seems to me it would really help if we had some concrete information about the performance abilities of the T's vehicles to go on (or light rail vehicles in general). All I know is that I've heard once or twice that buses can in fact typically do higher-G turns than light rail vehicles thanks to the suspension and tire setup on buses. But I don't have the slightest idea if the radial accelerations we are talking about actually fall into that performance gap.

[captainmidnight]

I'm no physicist or engineer, but if the current LRT trains could hit max speeds (assuming they don't already operate at max speeds) or thereabouts I am guessing PAT governs a lower speed for maintenance reasons. If the operators would hit full speed on the route, taking the twists and turns at a high speed would cause a good deal of stress on the trains, requiring more maintenance, more $$$, etc.

High speed turns on roller coasters (I know, not really apples to apples comparison here) are banked because of less stress on riders and the trains.

[Drover]

Originally Posted by BrianTH

So I'm trying to do some math. I think the buses are doing that 700-feet radius turn at around 40 mph, which by my math works out to a radial acceleration of just under 5 f/s2, or about 0.15 Gs.

Can T-style light rail systems handle that sort of radial acceleration? That seems to be the question.

I don't know how much time you spent on the north side when you were in Chicago (you went to U of C I think??), but if you ever rode the Brown Line train up toward its terminus.... they can take the turns between the Paulina and Addison stops and between the Montrose and Damen stops at about 40mph. The turning radius on those turns is about 1/8th of a mile, or 660 feet. If you view the turns from a satellite view side-by-side with the one under the Bloomfield Bridge and at the same scale, you'll find that the Bloomfield Bridge has a very comparable turning radius.

The video clip below opens up with the Brown Line taking the Paulina/Addison curve, filmed from the rear window of the last car. The distance from the Paulina to the Addison stop is just over 2700 feet. It travels that distance in a minute and 10 seconds. That's 38 feet per second, which is an average speed of 26mph -- and that's including full stops at both stations. So I think we can safely conclude that it averages well over 25mph while it's in motion between the stops. By extension, one can conclude T trains on the busway corridors would not appreciably hold up bus traffic.



G/S/M

[Blackbeauty212]

Originally Posted by Drover

I don't know how much time you spent on the north side when you were in Chicago (you went to U of C I think??), but if you ever rode the Brown Line train up toward its terminus.... they can take the turns between the Paulina and Addison stops and between the Montrose and Damen stops at about 40mph. The turning radius on those turns is about 1/8th of a mile, or 660 feet. If you view the turns from a satellite view side-by-side with the one under the Bloomfield Bridge and at the same scale, you'll find that the Bloomfield Bridge has a very comparable turning radius.

The video clip below opens up with the Brown Line taking the Paulina/Addison curve, filmed from the rear window of the last car. The distance from the Paulina to the Addison stop is just over 2700 feet. It travels that distance in a minute and 10 seconds. That's 38 feet per second, which is an average speed of 26mph -- and that's including full stops at both stations. So I think we can safely conclude that it averages well over 25mph while it's in motion between the stops. By extension, one can conclude T trains on the busway corridors would not appreciably hold up bus traffic.



G/S/M

3 thing that make this unfair -

1 - That bend was a not as tight as under the Bloomfield Bridge, nor is it as tight as the one under Neville Bridge or the one Near Negley Station and the Crossover Bridge before Homewood has two curves right behind each other

2 - This is on a Dedicated Railway...Not Rail layed within the street bed, there is a difference in two as far as max speeds allowed.

3 - Not really a fair comparison of Light Rail vs Heavy Rail.


Also to point out, I really dont consider 40MPH to be high speeds - Its usually 50mph or greater which is what the buses themselves are capable of when neigoitating those bends i think the max speed for buses is 60mph on some of the curves...So if they're behind a T-Car (if it was capable of doing even 40 mph around curves) would still need to slow down.

And if a T car even could keep up with the Buses on Curves.....still doesnt explain the fact that Traffic Lights will need to placed at the Oakland, E Liberty and Wilkinsburg ramps...Cause services to have to come to complete Stops that in itself would cause slower service on the Busway.

[Drover]

Dude. Whatever. I posted evidence, measurements, even video footage. You post your assertions. Why does heavy rail supposedly have an advantage? You say so without explaining why. Why does a dedicated rail ROW allow higher speeds than one integrated into a roadway? You say so without explaining why. You say the bend in the video isn't as tight as the one under the Bloomfield bridge, but if you look at satellite images of both at the same scale, one can see that you're just plain wrong.

The curves by the Negley station and the Homewood crossover have even wider turning radii than the one under the Bloomfield Bridge. They're wide sweepers that trains should barely even have to slow down for. And what the hell is the "Neville Street Bridge?"

Why would stoplights be necessary for trains if they're not for buses? And if they are, time them so they give vehicles coming off the busways the right of way. Problem solved. Have you even given this a bare minimum of thought, or did you just see objections without stopping to think if they were valid or could be easily overcome?