dariusj
@dariusj.bsky.social
I do think that a smarter system (potentially easier when GPS activated) could help here, by using on-vehicle passenger counts as an input to the arrival time model and delaying when the TSP request is started. With level boarding I'd imagine stop times should be predictable enough.
January 2, 2026 at 1:27 AM
I do think that a smarter system (potentially easier when GPS activated) could help here, by using on-vehicle passenger counts as an input to the arrival time model and delaying when the TSP request is started. With level boarding I'd imagine stop times should be predictable enough.
NYC also as far as I can tell performs green extension and red truncation only, without phase insertions or rotations, though the manual I found was pretty light on detail
January 2, 2026 at 12:25 AM
NYC also as far as I can tell performs green extension and red truncation only, without phase insertions or rotations, though the manual I found was pretty light on detail
I found an interesting paper from Portland (bpb-us-e1.wpmucdn.com/sites.northe...) where they went up to 40s extensions, using machine learning models to more accurately estimate bus arrival times to an intersection, even with a bus stop in between
bpb-us-e1.wpmucdn.com
January 2, 2026 at 12:25 AM
I found an interesting paper from Portland (bpb-us-e1.wpmucdn.com/sites.northe...) where they went up to 40s extensions, using machine learning models to more accurately estimate bus arrival times to an intersection, even with a bus stop in between
Wondering how Toronto's system performs with intervening bus stations, and whether it uses GPS in addition to in-street detection? NYC uses GPS systems only, and I have a suspicion we may not activate priority if there's a bus stop in between the bus' current position and the next intersection.
bpb-us-e1.wpmucdn.com
January 2, 2026 at 12:23 AM
Wondering how Toronto's system performs with intervening bus stations, and whether it uses GPS in addition to in-street detection? NYC uses GPS systems only, and I have a suspicion we may not activate priority if there's a bus stop in between the bus' current position and the next intersection.
Wondering what useful green extension times look like? I just found out that on blocks <300ft NYC only allows 5s extensions (that's most every short Manhattan block...), with a max of 18s, which seems extremely limited to me
January 1, 2026 at 11:50 PM
Wondering what useful green extension times look like? I just found out that on blocks <300ft NYC only allows 5s extensions (that's most every short Manhattan block...), with a max of 18s, which seems extremely limited to me
Since the bill was delivered on the 8th, shouldn't the veto deadline be tomorrow?
December 18, 2025 at 10:56 PM
Since the bill was delivered on the 8th, shouldn't the veto deadline be tomorrow?
You don't have to trust my or anyone else's authority, you can read and criticize the actual work.
May 13, 2025 at 11:36 PM
You don't have to trust my or anyone else's authority, you can read and criticize the actual work.
Having worked on the ETA report, I can tell you it was not primarily Alon's work. I think you're correct about the Marron report's writing, though if other members disagreed deeply with any part of it I'd think it wouldn't be published.
May 13, 2025 at 7:12 PM
Having worked on the ETA report, I can tell you it was not primarily Alon's work. I think you're correct about the Marron report's writing, though if other members disagreed deeply with any part of it I'd think it wouldn't be published.
The report is published by Marron, not just Alon, and ETA also argues Penn Expansion is a waste.
May 13, 2025 at 6:58 PM
The report is published by Marron, not just Alon, and ETA also argues Penn Expansion is a waste.
Consultants work for the agency commissioning the report, there's no additional independence there. Independent checks of project assumptions are welcome, especially with the costs of Penn Expansion.
May 13, 2025 at 6:50 PM
Consultants work for the agency commissioning the report, there's no additional independence there. Independent checks of project assumptions are welcome, especially with the costs of Penn Expansion.
Amazing how you lack substantive critiques. Very helpful, thank you!
May 13, 2025 at 6:47 PM
Amazing how you lack substantive critiques. Very helpful, thank you!
I'm actually sympathetic to this take, but you can derive these lessons from this report — for example, it explains how super elevation speeds up travel times, just as level boarding and electrification do.
May 6, 2025 at 4:02 AM
I'm actually sympathetic to this take, but you can derive these lessons from this report — for example, it explains how super elevation speeds up travel times, just as level boarding and electrification do.
I certainly wouldn't call those projects outright failures, but Second Avenue Subway has become a synonym for government dysfunction (see Ezra Klein). Not conducive to continued support for mass transit, obviously.
May 5, 2025 at 11:38 PM
I certainly wouldn't call those projects outright failures, but Second Avenue Subway has become a synonym for government dysfunction (see Ezra Klein). Not conducive to continued support for mass transit, obviously.
Yet agencies with relatively consistent funding like the MTA have subpar planning uninformed by international practice. Consistent funding isn't enough without pressure for high quality leadership and outcomes. The line for all these agencies no matter how well funded is that they don't have enough.
May 5, 2025 at 11:22 PM
Yet agencies with relatively consistent funding like the MTA have subpar planning uninformed by international practice. Consistent funding isn't enough without pressure for high quality leadership and outcomes. The line for all these agencies no matter how well funded is that they don't have enough.
Sure, this does not mean technical standards don't matter, or that pointing out modern planning practices isn't important.
May 5, 2025 at 11:14 PM
Sure, this does not mean technical standards don't matter, or that pointing out modern planning practices isn't important.
The Northeast Corridor has seen at least planning money for decades, but the planning since electrification has not produced good results. Bad practices need to be called out and addressed, or you burn remarkable amounts of cash.
May 5, 2025 at 11:12 PM
The Northeast Corridor has seen at least planning money for decades, but the planning since electrification has not produced good results. Bad practices need to be called out and addressed, or you burn remarkable amounts of cash.
I can't say this is a bad policy, but yeah you're just cranking the money spigot. Amtrak itself isn't an effective agency with capital projects or service planning, and you suggest nothing to fix that.
May 5, 2025 at 11:07 PM
I can't say this is a bad policy, but yeah you're just cranking the money spigot. Amtrak itself isn't an effective agency with capital projects or service planning, and you suggest nothing to fix that.
The point of a technical report isn't primarily in convincing, it's to show what needs to be done. Attacking bloated budgets and lacking progress is the main strategy, this is the alternative.
What's your reform strategy, demanding the money spigot be opened ever wider, with few visible results?
What's your reform strategy, demanding the money spigot be opened ever wider, with few visible results?
May 5, 2025 at 11:01 PM
The point of a technical report isn't primarily in convincing, it's to show what needs to be done. Attacking bloated budgets and lacking progress is the main strategy, this is the alternative.
What's your reform strategy, demanding the money spigot be opened ever wider, with few visible results?
What's your reform strategy, demanding the money spigot be opened ever wider, with few visible results?
What's unworkable is that tens of billions of dollars being pumped into the corridor will achieve not much more than status quo. The exact reason grand visions collapse is because the nuts and bolts were defective.
May 5, 2025 at 10:55 PM
What's unworkable is that tens of billions of dollars being pumped into the corridor will achieve not much more than status quo. The exact reason grand visions collapse is because the nuts and bolts were defective.
This is where you seem to contradict yourself; the technical standards are load bearing because they're not irrelevant, but actually incredibly important
May 5, 2025 at 10:38 PM
This is where you seem to contradict yourself; the technical standards are load bearing because they're not irrelevant, but actually incredibly important
Love your work but this does not look like the place to economize
en.m.wikipedia.org/wiki/2017_Ne...
en.m.wikipedia.org/wiki/2017_Ne...
March 29, 2025 at 3:33 PM
Love your work but this does not look like the place to economize
en.m.wikipedia.org/wiki/2017_Ne...
en.m.wikipedia.org/wiki/2017_Ne...
When passing through a space in passing, I still appreciate the architecture; I like Moynihan when I'm passing through it for work, for example. I think it is a fair callout that too much Penn conversation focuses on aesthetics alone, which is ultimately secondary
January 11, 2025 at 5:16 AM
When passing through a space in passing, I still appreciate the architecture; I like Moynihan when I'm passing through it for work, for example. I think it is a fair callout that too much Penn conversation focuses on aesthetics alone, which is ultimately secondary
I live near four small business supermarkets and a number of smaller grocery stores all concentrated on one block, and this enables access to high quality produce that's better than what you find in Trader Joe's. It's walkable and not corporate; is there a reason this arrangement isn't more common?
January 5, 2025 at 6:35 PM
I live near four small business supermarkets and a number of smaller grocery stores all concentrated on one block, and this enables access to high quality produce that's better than what you find in Trader Joe's. It's walkable and not corporate; is there a reason this arrangement isn't more common?
Anyone that spends time as a pedestrian in Manhattan (not just residents) will have a more pleasant experience. Drivers that still drive into the zone will save time, which has significant economic value. And 90%+ commuters are in fact taking public transit already and will see benefits
January 4, 2025 at 5:26 PM
Anyone that spends time as a pedestrian in Manhattan (not just residents) will have a more pleasant experience. Drivers that still drive into the zone will save time, which has significant economic value. And 90%+ commuters are in fact taking public transit already and will see benefits