Preparatory Work for M-1 Rail Begins

[ghettopalmetto]

4. Completely separated ROW for either BRT or light rail. Each of these is exactly as fast as the other. You can't do this along a roadway [[or, to be precise, I've never seen it done); this is done when a completely separate infrastructure pathway is created, as for instance by using abandoned freight ROW.

Buses and trains are equally fast.

Where? Cite existing example, please.

This claim gets thrown around a lot. Yet I've never seen a shred of evidence to support it.

[mwilbert]

.

What transit planners fail to understand, however, is that even using *every single* BRT bell and whistle, it is still physically impossible for a bus to operate as fast as rail. That's not my opinion--that's just physics.

I'm curious what physical laws you think are operating to cause this. I don't see why it would be impossible to apply whatever amount of force might be required to accelerate a bus at whatever rate you want? Each bus wheel has at least as much traction as each rail wheel--and if you did need more wheels, there isn't any physical law stopping you from adding them. On the flip side, buses actually seem to brake faster than LRTs. So what is the limiting factor you see here?

[iheartthed]

I'm curious what physical laws you think are operating to cause this. I don't see why it would be impossible to apply whatever amount of force might be required to accelerate a bus at whatever rate you want? Each bus wheel has at least as much traction as each rail wheel--and if you did need more wheels, there isn't any physical law stopping you from adding them. On the flip side, buses actually seem to brake faster than LRTs. So what is the limiting factor you see here?

He means efficiency. Bus lines cannot match rail lines on efficiency because it takes more buses to move large amounts of people.

[ghettopalmetto]

I'm curious what physical laws you think are operating to cause this. I don't see why it would be impossible to apply whatever amount of force might be required to accelerate a bus at whatever rate you want? Each bus wheel has at least as much traction as each rail wheel--and if you did need more wheels, there isn't any physical law stopping you from adding them. On the flip side, buses actually seem to brake faster than LRTs. So what is the limiting factor you see here?

Have you ever heard of flywheels? Friction?

If what you write is true, then a tractor-trailer could be designed to accelerate faster than a Corvette. It ain't happening.

[professorscott]

Where? Cite existing example, please.

This claim gets thrown around a lot. Yet I've never seen a shred of evidence to support it.

Why wouldn't it be so? Let me turn the example around and pose a question: Imagine two systems, each with completely separated right of way and absolute priority at intersections, or better yet, no intersections at all. Each is, let's say, two miles long, with only a stop at each end. One has steel tracks and carries light rail; the other is concrete and carries articulated buses.

Why would either vehicle necessarily be any faster than the other in that situation?

What makes most so-called BRT systems slower than most light rail systems is that almost every light rail system is built away from any road corridor and travels in a freight-rail style right of way with no interference from traffic at all. On road, BRT is more popular because it's less expensive than laying down tracks and accomplishes the same thing transportation-wise. If you can't completely get away from traffic, tracks and steel wheels don't buy you much beyond "sexy".

[ghettopalmetto]

Why wouldn't it be so? Let me turn the example around and pose a question: Imagine two systems, each with completely separated right of way and absolute priority at intersections, or better yet, no intersections at all. Each is, let's say, two miles long, with only a stop at each end. One has steel tracks and carries light rail; the other is concrete and carries articulated buses.

Why would either vehicle necessarily be any faster than the other in that situation?

Between the two of us, one has a PhD [[It isn't me.). You know that if you're going to make a claim, you have to provide evidence for it. Speculation doesn't Make It So.

The answer to your question has nothing to do with anything you mentioned. It has *everything* to do with the operating characteristics of the vehicles themselves. Think about it: flywheels and friction. What could either one of those things have to do with vehicular performance?

What makes most so-called BRT systems slower than most light rail systems is that almost every light rail system is built away from any road corridor and travels in a freight-rail style right of way with no interference from traffic at all.

I'm not talking about comparing apples-to-oranges. All things equal, rail will outperform bus. Every time. Put a bus on its own road along a railroad right-of-way, with no intersections or grade crossings, and it will still underperform any light rail train operating under those same conditions.

If you look at the Shirley Busway in Northern Virginia, bus ridership along I-395 dropped *precipitously* after the Springfield Metro Station opened--despite the rail line having an indirect route to the Pentagon and downtown, making stops along the way, and having higher fares.

The reason that there is no data on BRT outperforming light rail, is because it hasn't been done. Anywhere. Ever.

On road, BRT is more popular because it's less expensive than laying down tracks and accomplishes the same thing transportation-wise. If you can't completely get away from traffic, tracks and steel wheels don't buy you much beyond "sexy".

BRT isn't popular At. All. There are only five bus routes in the United States designated as "BRT". None--not a single one--matches the performance of a light rail system. Cleveland's is considered the best, and even that is a far cry from the 60-year-old rail service.

[mwilbert]

Have you ever heard of flywheels? Friction?

If what you write is true, then a tractor-trailer could be designed to accelerate faster than a Corvette. It ain't happening.

And of course it could. But you would need a lot of rubber, and it would be stupid for other reasons. However the main reason that a tractor-trailer can't accelerate faster than a Corvette is the difference in mass relative to torque. On the other hand, an LRV is heavier than a bus. So your argument wouldn't make much sense even if it were true.

[ghettopalmetto]

And of course it could. But you would need a lot of rubber, and it would be stupid for other reasons. However the main reason that a tractor-trailer can't accelerate faster than a Corvette is the difference in mass relative to torque.

Bingo. You're on the right path. Keep going....

[mwilbert]

Bingo. You're on the right path. Keep going....

If you think it is a law of physics that an LRV has more torque/mass than a bus, you don't know what a law of physics is. And you think that you can't have a flywheel, or capacitors, in a bus? Do you think there are no hybrid buses?

[ghettopalmetto]

If you think it is a law of physics that an LRV has more torque/mass than a bus, you don't know what a law of physics is. And you think that you can't have a flywheel, or capacitors, in a bus? Do you think there are no hybrid buses?

Of course there are flywheels in buses. Think about why that is.

And anyone who's ever been driving behind a bus or tractor trailer will tell you...they take a LOOOOONG time to go from standing start to the speed limit. It takes quite a bit of energy to get a flywheel moving on a 60,000 lb vehicle...energy that has to be produced by a diesel engine with lots of moving parts. You can actually do calculations for this, depending on which vehicle you choose.

But I'm not here to tell you what to believe. I'm just claiming that no Sexybus is allowed to violate fundamental laws of mechanics.

[mwilbert]

You didn't understand my point. You can actually use the flywheel to store energy to be used when you start up. Physics doesn't require the flywheel to stop when the vehicle stops; you could use it to store energy from braking. Your notion of what is prohibited by the fundamental laws of mechanics is incorrect.

The fact that people don't usually build rapidly accelerating buses has everything to do with the fact that most buses run in traffic on streets with fairly low speed limits and frequent stops, or are express buses that don't start and stop much. It has nothing to do with the impossibility building such buses.

[ghettopalmetto]

You didn't understand my point. You can actually use the flywheel to store energy to be used when you start up. Physics doesn't require the flywheel to stop when the vehicle stops; you could use it to store energy from braking. Your notion of what is prohibited by the fundamental laws of mechanics is incorrect.

I know how flywheels work, thank you. Does your flywheel store magic energy? Or does the stored energy actually have to come from somewhere? Like, maybe the bus has to accelerate first? Even with flywheels, do you enjoy driving behind a bus or a tractor trailer? Or do you maybe get into the passing lane at the first opportunity?

The fact that people don't usually build rapidly accelerating buses has everything to do with the fact that most buses run in traffic on streets with fairly low speed limits and frequent stops, or are express buses that don't start and stop much. It has nothing to do with the impossibility building such buses.

Or, ever. Why doesn't Cleveland's Magical Bus use your "rapidly accelerating buses"? Oh, that's right--because they don't fucking exist. Unfortunately, any transit system constructed in Detroit will have to exist in the real, physical world, and not the Land of Wouldas Couldas and Shouldas.

I have no idea what you're trying to prove, other than you value your own off-the-cuff opinion more than reality.

[RO_Resident]

Where? Cite existing example, please.

This claim gets thrown around a lot. Yet I've never seen a shred of evidence to support it.

Both are constrained by human comfort, not by the absolute physical capabilities of the vehicles. Maximum bus acceleration is typically 2 mphps, light rail 3mphps.

[ghettopalmetto]

Both are constrained by human comfort, not by the absolute physical capabilities of the vehicles. Maximum bus acceleration is typically 2 mphps, light rail 3mphps.

Eh, that's only a difference of 50%. No big whoop. Just paint the bus purple, mount an expensive PR campaign, and no one will ever know, right?

[ABetterDetroit]

with a formal ground breaking September 15.

http://www.detroitnews.com/article/2...supporters-say

Can we use this thread to discuss initial work on the project?

Apparently not, must reargue same arguments about M-1 as the last dozen threads about it like its new everytime. Havta admit tho that picturing a bus with corvette 0-60 times was pretty funny in my imagination.

[RO_Resident]

Eh, that's only a difference of 50%. No big whoop. Just paint the bus purple, mount an expensive PR campaign, and no one will ever know, right?

Marginal difference. To get up to 35 mph, the bus will take ~18 seconds, light rail ~12 seconds. So that's a maximum difference of ~12 seconds to go from stop to stop under maximum acceleration and maximum deceleration under free flow conditions.

Like I said, human comfort is a constraint, along with traffic, spacing between stops, signal preemption, dwell time, etc.

[Junjie]

BRT isn't popular At. All. There are only five bus routes in the United States designated as "BRT". None--not a single one--matches the performance of a light rail system. Cleveland's is considered the best, and even that is a far cry from the 60-year-old rail service.

It's hard to figure out why you attribute this to the vehicles themselves, though. The rail line [[Red) in Cleveland has fully grade-separated right of way and makes 8 stops between Tower City and Windermere. The "BRT" line runs on the street [[e.g. has to pass through intersections and stop at signals) and makes 33[[!) stops. I defined rapid transit as dedicated right of way + frequency, but let's add "limited stop service" to the list. 33 stops in 7 miles is not rapid transit, that's local bus in a dedicated lane. It's no surprise the rail does far better.

As far as northern VA, let me speak from personal experience as a two-year commuter from Van Dorn [[next to last stop on Blue Line) in to Foggy Bottom. For the first year I rode the Blue Line exclusively because I assumed that rail had to beat bus, especially over such a long distance. But eventually I noticed all these people in ties standing at bus stops on the roads near my apartment in the morning. It turns out that while the frequency isn't as good, buses make the trip from Van Dorn to the Pentagon significantly faster than the train because they take a direct route on what are basically dedicated lanes [[HOV3) on I395. So I switched to taking the bus if I happened to be leaving at the time when a bus was definitely coming soon, and doing so saved me time [[and money) over the train.

I'm not saying the vehicle doesn't matter at all, but I think it's pretty clear that the design of the actual system has much more to do with how quickly or reliably you get someplace. If you put a train in tracks on the street and gave it 33 stops in 7 miles [[aka, a streetcar) it's not going to beat a bus running in a purpose-built exclusive viaduct with 8 stops.

More people might still ride the train just because of the train > bus social bias, comfort issues or whatever, but that's a different point from performance.

[professorscott]

I'm not saying the vehicle doesn't matter at all, but I think it's pretty clear that the design of the actual system has much more to do with how quickly or reliably you get someplace.

Thank you, Junjie. Precisely the point I was trying to make, but you made it much more succinctly. I have to work on my succinct.

[Junjie]

Thank you, Junjie. Precisely the point I was trying to make, but you made it much more succinctly. I have to work on my succinct.

Ha, well looking at my own posts I'm rarely the most succinct either, but glad if I'm at least being clear.

Anyway apologies for starting this BRT tangent, I know the argument has been hashed out here before. Hurray M-1 construction!

[emu steve]

It's hard to figure out why you attribute this to the vehicles themselves, though. The rail line [[Red) in Cleveland has fully grade-separated right of way and makes 8 stops between Tower City and Windermere. The "BRT" line runs on the street [[e.g. has to pass through intersections and stop at signals) and makes 33[[!) stops. I defined rapid transit as dedicated right of way + frequency, but let's add "limited stop service" to the list. 33 stops in 7 miles is not rapid transit, that's local bus in a dedicated lane. It's no surprise the rail does far better.

As far as northern VA, let me speak from personal experience as a two-year commuter from Van Dorn [[next to last stop on Blue Line) in to Foggy Bottom. For the first year I rode the Blue Line exclusively because I assumed that rail had to beat bus, especially over such a long distance. But eventually I noticed all these people in ties standing at bus stops on the roads near my apartment in the morning. It turns out that while the frequency isn't as good, buses make the trip from Van Dorn to the Pentagon significantly faster than the train because they take a direct route on what are basically dedicated lanes [[HOV3) on I395. So I switched to taking the bus if I happened to be leaving at the time when a bus was definitely coming soon, and doing so saved me time [[and money) over the train.

I'm not saying the vehicle doesn't matter at all, but I think it's pretty clear that the design of the actual system has much more to do with how quickly or reliably you get someplace. If you put a train in tracks on the street and gave it 33 stops in 7 miles [[aka, a streetcar) it's not going to beat a bus running in a purpose-built exclusive viaduct with 8 stops.

More people might still ride the train just because of the train > bus social bias, comfort issues or whatever, but that's a different point from performance.

I agree with you.

I took the Yellow/Blue line from Van Doren Wednesday afternoon [[during rush hour) to downtown and it took for ever.

My trip to work which was a 29 [[express along the 395 HOV lanes) bus to the Pentagon and then to downtown was faster each morning [[also rush hour).

If I'm flying out of Reagan I take a 29N bus along Duke to King Street subway and then the short subway ride to the airport.

One thing which is not highlighted here:

In Detroit folks can opt to take public or private transit and weigh the options in terms of time, cost, flexibility, social bias, etc. etc.

In D.C. area a lot of the private transportation options aren't that desirable. Sitting in traffic [[vs. sitting in a subway car reading the newspaper), very high cost of parking, etc. [[BTW, also the federal government and some private employers subsidize employees using public transit).

In Detroit opting to drive [[vs. public transit) is usually an easy decision. Not so in D.C. area.

BTW, M-1 is like the original subway back in say 1976 which served mostly just downtown. It did not serve the 'burbs.

One can say that M-1 2016 will be similar to the D.C. subway system circa 1976.

[Pickford-Bentler]

Of course there are flywheels in buses. Think about why that is.

And anyone who's ever been driving behind a bus or tractor trailer will tell you...they take a LOOOOONG time to go from standing start to the speed limit. It takes quite a bit of energy to get a flywheel moving on a 60,000 lb vehicle...energy that has to be produced by a diesel engine with lots of moving parts. You can actually do calculations for this, depending on which vehicle you choose.

But I'm not here to tell you what to believe. I'm just claiming that no Sexybus is allowed to violate fundamental laws of mechanics.

And LRV gets energy from an external source of power - the grid. Vehicle acceleration is a function of power to weight. The electric motors on an LRV can transmit large amounts of power and the torque curve is instantaneous and smooth. The LRV, because it does not have to carry on-board heat engine to generate power, saves weight.

A bus will be limited in acceleration due to the low peak power of the on board heat engine. Although a diesel has lots of torque in a bus, the peak power is typically about 350hp. To accelerate like the DC Metro train, I would guess that the engine would need 3,500 hp. So it would essentially be an engine on wheels with reduced passenger space.

Then there is the issue of doing work against friction. Rubber on concrete requires more work than steel on steel.

Then, as the professor pointed out, there is the jerk vector. A drive system that uses and ICE and a Mechanical transmission does not have a smooth torque curve. A system with E-Motor drive does. For example, auto journalists rave about the dynamics of the Tesla.


When I drive on I-66 in the section where the Metro runs in the median, it amazes me how fast it get up to the speed of cars doing about 60 from one of its stops.

The key point, IMO, is that an LRV can tap a virtually unlimited source of power wherein a bus is limited to its on-board heat engine - the ICE.

[ghettopalmetto]

And LRV gets energy from an external source of power - the grid. Vehicle acceleration is a function of power to weight. The electric motors on an LRV can transmit large amounts of power and the torque curve is instantaneous and smooth. The LRV, because it does not have to carry on-board heat engine to generate power, saves weight.

A bus will be limited in acceleration due to the low peak power of the on board heat engine. Although a diesel has lots of torque in a bus, the peak power is typically about 350hp. To accelerate like the DC Metro train, I would guess that the engine would need 3,500 hp. So it would essentially be an engine on wheels with reduced passenger space.

Then there is the issue of doing work against friction. Rubber on concrete requires more work than steel on steel.

Then, as the professor pointed out, there is the jerk vector. A drive system that uses and ICE and a Mechanical transmission does not have a smooth torque curve. A system with E-Motor drive does. For example, auto journalists rave about the dynamics of the Tesla.


When I drive on I-66 in the section where the Metro runs in the median, it amazes me how fast it get up to the speed of cars doing about 60 from one of its stops.

The key point, IMO, is that an LRV can tap a virtually unlimited source of power wherein a bus is limited to its on-board heat engine - the ICE.

Thank you. Much better stated than I could have stated. For what it's worth, the coefficient of static friction of tires-on-road [[~1.0) is about double the coefficient of static friction of steel-on-steel [[0.50).

The issue is, the proposed network proposed by SEMCOG is not a consideration of "grade-separated bus with limited stops" versus "streetcar running in mixed traffic in the roadway". Assuming that routing, station spacing, fare payment system, boarding and alighting, and all other operating characteristics are equal [[the system design), then rail is going to beat the pants off a bus every time...in speed, capacity, passenger comfort, and operating cost.

Yet, for some reason, folks take it as a given that BRT is somehow "cheaper" and "equal". If it were, I think we'd see more cities constructing BRT instead of expanding their light rail networks. Just because the Greater Cleveland RTA took 25 years to end up with a $250 million streetscaping project doesn't make it a terrific idea to be applied universally. And quite honestly, if Ron Tober were still the GM at GCRTA [[he moved to Charlotte to build the Lynx system), Euclid Avenue would have been light rail. Current GM Joe Calabrese is well-known for having an anti-rail bias. I'm not even going to get into the artificially inflated development numbers....

Now, it might make sense to have some kind of express bus on Hall Road. But for a busy urban corridor where transit ridership already exists in respectable numbers, I think people are going to feel ripped-off that their new transit miracle is a lot like what they already had. People aren't idiots...if you tell them "rapid transit" and it still takes an hour to get from downtown to Royal Oak, they're going to be pissed.

[SyGolden48236]

So, work has officially begun on The Hipster Hauler. I wonder how many years late and how many millions over budget this boondoggle is going to be, as was the case with the People Mover.

http://www.nytimes.com/1987/08/01/us...ail-opens.html

[Junjie]

The issue is, the proposed network proposed by SEMCOG is not a consideration of "grade-separated bus with limited stops" versus "streetcar running in mixed traffic in the roadway".

Right, I think this is where things got confusing. The question was "is the current streetcar in mixed traffic designed to be extended as rapid transit in the future"? And then, since the answer seemed to be yes, "how would such an extension interact with the BRT plan?" So we started off apples to oranges, but with the potential to convert the apple into an orange north of Grand.

Given its history and the lack of existing rail in Detroit to compare it to, it seems there's already a lot of confusion about exactly what M-1 is. I certainly don't envy those whose task it would be to sell a phase 2 extension as rapid transit based on the public's experience with the phase 1 streetcar operations.

Assuming that routing, station spacing, fare payment system, boarding and alighting, and all other operating characteristics are equal [[the system design), then rail is going to beat the pants off a bus every time...in speed, capacity, passenger comfort, and operating cost.

Agreed.

People aren't idiots...if you tell them "rapid transit" and it still takes an hour to get from downtown to Royal Oak, they're going to be pissed.

Agreed. I'm wary of BRT proposals in general as compared to rail rapid transit and heartened by what professorscott posted above about M-1's design considerations for future extensions.

[dtowncitylover]

So, work has officially begun on The Hipster Hauler. I wonder how many years late and how many millions over budget this boondoggle is going to be, as was the case with the People Mover.

http://www.nytimes.com/1987/08/01/us...ail-opens.html

You and TennisandMath should trade talking points.