General MBTA Topics (Multi Modal, Budget, MassDOT)

[bakgwailo]

This discussion about turning radii, vehicles, stations, yards, etc is important and will get lost in this general MBTA thread. Can someone please move all the green line vehicle & modernization discussion to the Type 10 thread so it is properly archived for reference?

Thanks.

Yup, I take the blame, too, I should have originally posted it in the Type-10 thread and not here.

 

[jass]

Re: Green Line proposed platform length

I don't believe anywhere in the world is running automated trains/trams on lines that aren't grade separated.

These are vehicles that are supposed to run until 2070.

We already have driverless shuttles that run on virtual tracks without grade separation

https://www.youtube.com/watch?v=YPHHGHT5sEI

 

[millerm277]

Re: Green Line proposed platform length

These are vehicles that are supposed to run until 2070.

We already have driverless shuttles that run on virtual tracks without grade separation

https://www.youtube.com/watch?v=YPHHGHT5sEI

No, we have an experimental vehicle operating in a very limited fashion. Which may or may not ever advance far enough to be of widespread, cost-effective, reliable use.

---------------------------

I think it's quite likely that we'll have said automated trains in mixed/non-separated traffic some day, it's at least a simpler problem than self-driving are. (I am skeptical about how soon you'll really see them either, but that's outside the bounds of this forum).

But that doesn't change that there is nowhere in the world running such a thing. I disagree with acting like Boston or the US in general is "behind the times" or doing something "backward" as a result.

 

[HenryAlan]

That thing is ridiculously slow and light weight. There is nothing equivalent to high capacity rail that can safely operate outside a controlled environment and entirely without human participation. Only theoretical, and not all that close to a reliable production model.

 

[tysmith95]

That thing is ridiculously slow and light weight. There is nothing equivalent to high capacity rail that can safely operate outside a controlled environment and entirely without human participation. Only theoretical, and not all that close to a reliable production model.

Copenhagen metro. A few of the metro lines in Rome are driverless. A number of people movers at airports, the one at the Atlanta airport basically operates as a high capacity subway system.

 

[Arlington]

That thing is ridiculously slow and light weight. There is nothing equivalent to high capacity rail that can safely operate outside a controlled environment and entirely without human participation. Only theoretical, and not all that close to a reliable production model.

But a swarm of small vehicles can eat a big vehicle's lunch. The 787, operating directly between smaller demand nodes, has killed the A380's big-hub business. Same risk/opportunity here.

 

[jass]

Copenhagen metro. A few of the metro lines in Rome are driverless. A number of people movers at airports, the one at the Atlanta airport basically operates as a high capacity subway system.

Both BART and WMATA were built 100% automated in the 1960s

 

[Equilibria]

Copenhagen metro. A few of the metro lines in Rome are driverless. A number of people movers at airports, the one at the Atlanta airport basically operates as a high capacity subway system.

Those systems don't have grade crossings for vehicles and pedestrians.

 

[bigpicture7]

Those systems don't have grade crossings for vehicles and pedestrians.

Spot on.

The ATL airport train is exactly this: a horizontal elevator. It is an entirely closed system. The entire tube is sealed off while the train is running; there is a wall of doors that completely block the tracks.

Light rail that goes through automobile and pedestrian intersections is nothing like that whatsoever from an engineering standpoint.

When an algorithm is ready for prime time that can anticipate when the BU kid running across the tracks in her flip-flops will accidentally drop her phone, turn around and retrieve it as the train is coming...let me know...because anticipating that is exactly what GL operators currently do.

 

[Jahvon09]

My theory is that some crazed nut job might or could try to hack into the system & reprogram the vehicles to go haywire and cause catastrophic accidents!

 

[JeffDowntown]

Copenhagen metro. A few of the metro lines in Rome are driverless. A number of people movers at airports, the one at the Atlanta airport basically operates as a high capacity subway system.

Airport people movers are total walled gardens -- totally protected right-of-way.

Nothing like operating on the surface Green Line open right-of-ways.

Yesterday I saw students around BU West walking directly in front of an approaching trolley -- expecting the trolley to stop for them to cross, short of the station.

 

[jass]

Yesterday I saw students around BU West walking directly in front of an approaching trolley -- expecting the trolley to stop for them, short of the station.

And thats the absolute easiest thing to program.

Youre essentially referring to forward collision detection and automatic breaking - something that has been available in luxury cars for 10+ years and has now filtered its way to budget models.

I don't think we're anywhere close to self-driving CARS.

But a self-driving train is simply taking the tech we've had since the 1960's, and adding forward collision detection to stop for pedestrians at the crosswalks.

 

[JumboBuc]

And thats the absolute easiest thing to program.

Youre essentially referring to forward collision detection and automatic breaking - something that has been available in luxury cars for 10+ years and has now filtered its way to budget models.

I don't think we're anywhere close to self-driving CARS.

But a self-driving train is simply taking the tech we've had since the 1960's, and adding forward collision detection to stop for pedestrians at the crosswalks.

I think what JeffDowntown is getting at is that computers can't predict human behavior (yet) nearly as well as humans can. A human driver and a computer driver can both observe an obstacle in their path and apply the brakes. But a human driver is better at anticipating which pedestrians might wander into their path versus which pedestrians will stand clear. And along the Green Line, drivers need to make a lot of these judgments.

Stop for every person moving along the right-of-way and the train will never get anywhere, but stop for none of them and you'll have fatalities. Human drivers are good at picking up the subtle cues to determine for whom the train needs to be stopped and whom the train can ding at but drive safely past. It's more subtle than just detecting an obstacle and applying brakes.

Just as automated trains will (and have) come long before automated cars, the Green Line will be the last of Boston's transit lines to be automated. On the Red, Orange, and Blue, the correct response to any obstacle in the ROW is to apply brakes immediately. On the Green, it's up to the conductor to determine to what extent brakes need to be applied (i.e., figure out the correct brakes-to-bell ratio).

 

[JeffDowntown]

And thats the absolute easiest thing to program.

Youre essentially referring to forward collision detection and automatic breaking - something that has been available in luxury cars for 10+ years and has now filtered its way to budget models.

I don't think we're anywhere close to self-driving CARS.

But a self-driving train is simply taking the tech we've had since the 1960's, and adding forward collision detection to stop for pedestrians at the crosswalks.

Then why was that pedestrian crossing the road in Arizona killed? Forward collision prevention with a random, unanticipated obstacle is not a solved problem! Picking out which pedestrian is likely to move in front of the train is not trivial. Particularly since trolley right-of-ways have tons of pedestrians along them (near stops).

 

[jass]

Then why was that pedestrian crossing the road in Arizona killed? Forward collision prevention with a random, unanticipated obstacle is not a solved problem!

The Uber vehicle detected the pedestrian.

The Uber engineers programmed the vehicle to ignore that input and plow ahead.

https://jalopnik.com/uber-self-driving-car-detected-pedestrian-killed-in-cra-1825834016

I think what JeffDowntown is getting at is that computers can't predict human behavior (yet) nearly as well as humans can. A human driver and a computer driver can both observe an obstacle in their path and apply the brakes. But a human driver is better at anticipating which pedestrians might wander into their path versus which pedestrians will stand clear. And along the Green Line, drivers need to make a lot of these judgments.

Stop for every person moving along the right-of-way and the train will never get anywhere, but stop for none of them and you'll have fatalities. Human drivers are good at picking up the subtle cues to determine for whom the train needs to be stopped and whom the train can ding at but drive safely past. It's more subtle than just detecting an obstacle and applying brakes.

Just as automated trains will (and have) come long before automated cars, the Green Line will be the last of Boston's transit lines to be automated. On the Red, Orange, and Blue, the correct response to any obstacle in the ROW is to apply brakes immediately. On the Green, it's up to the conductor to determine to what extent brakes need to be applied (i.e., figure out the correct brakes-to-bell ratio).

While I agree with what you're saying, the MBTA has removed most of the agency the drivers have in predicting what pedestrians are doing. The MBTA has done this by imposing 7mph speed limits, and putting stop signs before some of the crossings. Of course, you also have a station every 20 feet, so the trains barely make it to 7mph before having to hit the brakes.

So in the Uber case, Uber put speed as a priority, and so they told the computer not react because its probably a false positive.

MBTA is the opposite. They would say treat every observation as a reason to stop.

Which is pretty much what they already do.

Which Im ok with, because I rather have am automated train moving at 5mph every 90 seconds, rather than a human driven train going at 7mph every 6 minutes.

The whole point of automation is that you can run a bunch more service since you cut the operator costs.

 

[HenryAlan]

Copenhagen metro. A few of the metro lines in Rome are driverless. A number of people movers at airports, the one at the Atlanta airport basically operates as a high capacity subway system.

And BART and DC Metro, etc., but they all operate in controlled environments. The Green Line does not, which is why I specified "high capacity rail that can safely operate outside a controlled environment," which is the actual circumstance we're discussing.

 

[Arlington]

As far as AI is concerned, a trolley on a track a way simpler problem than driving a car
- no need to detect or infer the edge of the roadway
- all road will be familiar and pre-programmed down to the mm
- all track and road signals will be exactly known (it will either know electronically, or will know where to look and when a look was insufficient)
- GPS + track location = super accurate awareness
- no computation devoted to staying in lane or planning evasive maneuvers
- no speeds over 50 (ish?) (limits how far ahead to consider)

Between "watching videos" and several years (across all seasons and conditions) of co-operation with humans, the system will know every little bump and feel of every route, even wrong-railing, and base its actions as a rookie on what amounts to hundreds of years of operations.

The vehicle will know the exact place it will be "now" and "seconds from now"...the only question will be how quickly (and at what speed) it will arrive "there" and has it detected and tracked all people/objects that might be "there"

It is the "forward collision avoidance" problem (which Subarus have been really good at since 2012) both straight ahead, and tracking objects in motion into that path from any other direction. Add a few more sensors, and the train will be "aware" of all interactions near the train within inches in every direction.

The system will likely know that that BU student is drunk just by looking at their gait, and will see that a crossing car is going too fast to stop (by knowing its exact speed and direction)

(As noted, Uber had told its killer car to treat unexpected objects as if they were a cardboard box or plastic bag blown in--this was a programming failure not a technical barrier)

And it will not get tired or distracted.

Perhaps, as on the Docklands Light Railway, a human will be on board to answer questions and provide a sense of security (or to check fares), but the main value a human will add will not be the ordinary operation of a tracked vehicle and the anticipation of nearby events/interactions/objects.

Economically, the highest paid drivers are at greatest risk first because their high wage rate makes it easier to justify expensive sensor packages (LIDARs and things to infer density (life forms) vs empty shapes (boxes and bags).

Uber drivers will come next because eventually computers will underprice them as "employees" Your personal car will come last (except it already has FCW and AEB, which are most of the game for tracked vehicles) because it still has to be priced as a car, not an economic tool.

AEB = Automatic Emergency Braking; Just like it sounds, the car will apply the brakes without driver input when an accident is likely. Relies on a Forward Collision detection, warning, or avoidance sensor.

FCW = Forward Collision Warning; the ability to do the math (continuously) based on the position and velocity of objects to project collisions in upcoming seconds. When a collision is of high enough likelihood, it can warn to mitigate or avoid the accident by braking.

FCW has progressed rapidly. From silent, to audible, to automatic. Taking the typical Toyota as an example:

2010 = Silent. Systems would not actually warn the driver but would warn other systems: boosting braking power, pre-tension seat belts, hoping the driver would act. Some would brake only after an accident was unavoidable.

2015 = systems would sound an alert in time for a human to stop the accident, but if ignored, only brake to mitigate impact, not avoid. Goal: reduce the car's speed at impact.

2018 = systems would both warn and trigger AEB in time to *avoid* an accident in most cases

LIDAR is *not* needed for FCW and AEB, which rely in stead on inexpensive radars & cameras (Toyota, Chrysler) or two cameras (Subaru)

 

[Joel N. Weber II]

I think the Type 10 cars should be designed with the assumption that they might have a human operator in the beginning who might become unnecessary at some point during their life. The partition between the operator cab and the rest of the car should probably be installed with something like a dozen bolts so that it can be removed if / when the time comes.

The operator should only be removed if the technology to do so is successfully developed and demonstrated elsewhere and it becomes a matter of integrating existing, known technology with the Green Line trains. There just aren't enough people working as Green Line operators in the first place for automation to be worth making a major investment in; there are a bit fewer than a hundred two car trains, so if we can get down to one operator per train, there are a few hundred full time jobs.

However, we also started this discussion of whether to have a human operator when I was bringing up the question of how precisely the train can be aligned on the platform, and that might be worth automating even if we can't automate the stopping for a pedestrian functionality.

 

[Joel N. Weber II]

Economically, the highest paid drivers are at greatest risk first because their high wage rate makes it easier to justify expensive sensor packages (LIDARs and things to infer density (life forms) vs empty shapes (boxes and bags).

Uber drivers will come next because eventually computers will underprice them as "employees" Your personal car will come last (except it already has FCW and AEB, which are most of the game for tracked vehicles) because it still has to be priced as a car, not an economic tool.

I think I've been reading that LIDAR has traditionally been around $50,000 per vehicle. That's approximately free for a Green Line train car that costs millions of dollars, and probably less than the cost of a full time employee for one or a few years, but not affordable for a typical Nissan Leaf buyer.

There is also some work being done to try to reduce the cost of LIDAR, and Elon Musk seems to think full self driving can be done without LIDAR. (Indeed, humans do driving with little more than a pair of optical sensors.)

 

[chmeeee]

There is also some work being done to try to reduce the cost of LIDAR, and Elon Musk seems to think full self driving can be done without LIDAR. (Indeed, humans do driving with little more than a pair of optical sensors.)

I don't put too much faith in what Elon Musk thinks, given that he seems to have no issues releasing an autopilot system to the general public when it can't even figure out how to not drive into a concrete divider.

https://www.youtube.com/watch?v=6QCF8tVqM3I