afransen
Senior Member
Lane switching hurts highway capacity. In a mostly AV world, I imagine that can be minimized. Leaving aside fantasies around eliminating stopping distances/headways, I don't think AVs will improve highway capacity much..
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The Coming Disruption of Transport
- Thread starter kEiThZ
- Start date
rbt
Senior Member
One thing a wholly AV implementation does gain is the ability to prevent roadways from being congested. Scheduling of road/highway time-slots and implementation of ground or takeoff delay programs as seen at airports would allow running at optimal capacity or slightly under, but never over.
You may find that your 1 hour commute is still 55 minutes BUT you spend the first 20 minutes reading in your driveway (or at the table eating breakfast if you schedule early).
Preventing roadways from being over capacity could allow for large savings in emergency services. About 50% of fire stations could be removed from Toronto while maintaining current response times if roadways were guaranteed to always be clear (vehicles always had sufficient space to move to the side and clear intersections).
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2transpo
New Member
What reason would I have to not be confident in Elon's timeline? Everyone agrees with him. TuSimple, Waymo and others are all predicting that every practical challenge for AV development will be solved over the next 2-3 years. Besides, CN has insulated themselves from AV disruption with their investments in technology and their trucking line.
One thing I'm surprised about is that CN bought Lion Electric trucks. From testing, the data shows that the Tesla Semi is the best EV truck on the market and it isn't even close, especially on range.
This isn't just about Milton. What about Pitt Meadows with CP expanding their terminals and causing massive disruption? What about CP and CN refusing to share tracks in Saskatoon, causing disruption downtown? A good portion of people in this country would love to see railways vanish, and AV trucks make this not only possible, but attractive.
Freeways are generally built insulated from population centers, but railways were not and as such they cause greater disruption to quality of life.
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Towered
Superstar
Then we can finally get that midtown GO line!
2transpo
New Member
This provides a good pivot to the disruption of transit. There is a pretty good chance GO rail will not exist in 15 years. This again points to autonomous vehicles.
I'm not sure how many of you are familiar with Brad Templeton. He has worked with Waymo before and is a prominent pundit in the space of AVs. He has some good blog posts which sum transit's prospects and they aren't pretty.
The Decline of Mass Transit
www.templetons.com
The thing is that the costs of ride hailing autonomous vehicles is so low, it will be difficult to justify new transit and transit use will also decline. Most of all, with no freight, you can guarantee that CP will sell the line for a pretty penny to developers.
afransen
Senior Member
We simply haven't the highway capacity for everyone to use AVs. Rideshare AVs increase VMTs because they need to shuttle empty between rides. Only ways around this are:
- Encourage people (financially) to pool their rides for long distances in minibuses. The encouragement comes in the form of high tolls at peak times to manage the high demand for road space, which gets passed through to fares.
- Hope Elon comes through with his loop tunnels and can build them everywhere pronto. And this is less like cars and more like transit, really (captive rubber tired vehicles in tunnels).
The Templeton thread you mention uses the conceit of very short headways (1.5s) to say that dedicated minibus lanes can have very high capacity. I don't think 1.5s headways are safe, regardless of who's driving (AI or human), due to the lack of reaction time available in the event of mechanical problems or unexpected obstacles (assuming we are not talking about perfectly exclusive ROWs that may still have animals, humans, or debris appear). Practically speaking with a larger mini-bus type vehicle, maximum headway is probably 3-4s, and the utilization can't be 100% as there will be need for merging, etc. You can definitely move a lot of people with what would effectively be an AV BRT ROW.
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2transpo
New Member
The last mile problem really isn't much of a problem. The vast majority of transit riders walk to/from the station. Something like 80-90%.
To address the traffic problem:
Science | AAAS
www.sciencemag.org
There is also the fact that vehicle occupancy will be increased substantially, requiring fewer cars on the road.
To me the most interesting part about Templeton's blog is how he revealed that transit can often be grossly less energy efficient than EVs.
afransen
Senior Member
Hmm, I wonder if there might be a flaw in this reasoning.The last mile problem really isn't much of a problem. The vast majority of transit riders walk to/from the station. Something like 80-90%.
To address the traffic problem:
Science | AAAS
ETA: roads still have a capacity, even if we don't see as many jams related to imprecise human control. For as much AVs will improve flow and recover from slowdowns better than human drivers, they will likely tend to be conservative on headways (defensive driving).
2transpo
New Member
Why not build this instead of HFR?
This video addresses almost all of the technical criticisms levelled against hyperloop including capacity, switches, and boarding. At every step of the way, Virgin Hyperloop has demolished the naysayers' case against them. Are we going to get on board or will we be left behind? That is the choice. Hyperloop is ready. The engineering challenges are solved so lets do it.
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lenaitch
Senior Member
That CGI production "addresses" nothing. So far, one 1/2 km test track, two pax, no switches.
Sorry, I don't worship at your church.
Sorry, I don't worship at your church.
MrGoose
Active Member
It's a slick video I grant you that but what technical criticisms does it address??
How is the switching performed? I see trains merging tracks and splitting but I don't see a mechanism. Is it reliable at 500mph? Is there anyway to inspect the mechanism without having to pressurize the tube?
How about safety? You have vacuum tubes hundreds and thousands of miles long. Is the entire tube depressurized? How do you ensure catastrophic pressurization doesn't occur? If the tube is segmented, how do you build doors strong enough and fast enough to operate safely.
What about the pods? What happens if a pod loses power? What happens if a pod crashes into someone? At 500mph everyone's turning into pink mist. How do you ensure that the pods remain pressurized. Planes are inspected after every journey. That doesn't appear to be the case here.
How about reliability? What happens if there's a defect in the rail? At 500mph and with only cm of clearance, the tolerances on every part has to be pristine. One deformed part and the entire pod goes crashing into the side of the tube, taking down the whole system.
Finally, how do you propose making this economical? Giant vacuum tubes are made to order and not cheap. Space stations are giant vacuum tubes and are incredibly expensive. What is hyperloop but a space station moving inside another reverse space station at hundreds of miles an hour. All the problems of space travel without the hundreds of kilometers of tolerance.
crs1026
Superstar
HFR is effectively shovel ready and the technical issues are conventional railroading - well proven and understood.
Hyperloops are not shovel ready and any number of technical glitches or unforeseens can be presumed in the first few attempts.
We should not contemplate building the first prototype installation of anything that complex. Come back when someone else has worked the bugs out.
- Paul
Hyperloops are not shovel ready and any number of technical glitches or unforeseens can be presumed in the first few attempts.
We should not contemplate building the first prototype installation of anything that complex. Come back when someone else has worked the bugs out.
- Paul
sche
Active Member
First of all, the reason most people walk to transit stations is because of the last mile problem. If I can't get to a transit station I'll just drive.The last mile problem really isn't much of a problem. The vast majority of transit riders walk to/from the station. Something like 80-90%.
To address the traffic problem:
Science | AAAS
There is also the fact that vehicle occupancy will be increased substantially, requiring fewer cars on the road.
To me the most interesting part about Templeton's blog is how he revealed that transit can often be grossly less energy efficient than EVs.
As for traffic with AVs:
1. Induced demand
2. There is physically not enough space on the road in many places to accommodate everyone on cars, even if we had 4 people in every car. Cars are just not space efficient.
However tbh, I am very worried about autonomous vehicles. I think there is a very real possibility that they will cause the death of our cities and a renewed era of suburban and exurban car-centric sprawl. How can we encourage a built form that is still supportive of active transportation and transit when AVs are around? Autonomous electric car ride-hailing will just be too convenient and desirable.
The only thing about AVs that will definitely be good for our cities is the complete elimination of parking, which will definitely help improve the built environment by eliminating the single worst land use.
I really hope I'm wrong about AVs driving more low density sprawl though. Sprawl with electric AVs might not have the climate change and pollution problems of current sprawl, and might be slightly better without parking, but AVs don't change how infrastructure in car-dependent neighborhoods is far more expensive, or how sprawl is a horrible and inefficient use of land, or how active transportation and transit has considerable benefits for public health via exercise, or how cars make for a non-vibrant and unpleasant urban environment.
afransen
Senior Member
Hyperloop has a lot of technical problems. As long as companies like Virgin are developing it with private funds and no public subsidy, they can fill their boots and prove the naysayers wrong with a demonstration project that actually works over practical distances (vehicles actually get up to cruising speed, vacuum can be maintained over long distances, tolerant to leaks and mild damage to the tunnel). Until then, this is legitimately described as gadgetbahn and not to be used as an excuse to not invest in technology that is proven to work.
afransen
Senior Member
I think all these concerns are quite valid. AVs are not a panacea. We'll need to come up with mechanisms that encourage short distance trips to be done by active transportation (min trip charge, much like taxis and Uber use today) and long distance to be pooled with other users, or use AV shuttles to bring people to major transit stations. If we don't intervene, car traffic will increase to the point that they take as long as transit.