That’s not the right question. Did you ask him whether you can eliminate congestion by having increasing the roadways leading into a constrained CBD street network, so that those roadways deliver more cars per hour than the CBD streets can handle?
In many (most?) cases of congestion, the constraint isn’t in the roadways leading to the congested area - it’s the limited capacity of the congested area to absorb as many cars per hour as want to get there.
It doesn’t matter how many hotels are on the Loop. That’s not the limiting factor. The limiting factor is the capacity of the tunnel leading into the Loop station at the convention center. That tunnel can’t carry more than one or two thousand people per hour using passenger cars. So whether you have one hotel or a hundred hotels on the Loop line, no more than a few thousand people can take the Loop to the convention center during the morning Peak.
If you get one vehicle through the tunnel every five seconds (which would be really high and probably beyond the station capacity to handle), that’s only 700 cars per hour. No matter how long the line is beyond the LVCC, that’s your limit on how many people can take the Loop arriving at each end of the LVCC. Maybe 3K in a peak hour.
You can’t fit a shuttle bus into one of these tunnels. A passenger car like the Model Y is only about five feet tall. A typical passenger shuttle is about nine feet tall.
That’s another geometry issue, not a technology issue - because a bus (as opposed to a car) has to be tall enough for an adult to walk upright inside of it, rather than get straight into their seats from the outside.
It’s not a question of attitude, or positivity, or imagination. The system only has a certain amount of capacity. And it’s not large enough, in terms of people per hour, to fully serve attendees at the convention center.
Well, that’s a physicist answer to a practical problem. Unfortunately, practical wins. It’s well known among city and traffic planners (including those who deal with tunnels!) that widening a highway only works for a short time, because it induces demand (during the period immediately after construction when traffic flows again for a while) and within a short time, it’s the same same.
Here’s a pic of the Katy highway in Houston. They kept adding and adding lanes, sure that would cure the problem. It’s now 26 lanes wide.
Did it fix them problem? Nope. A short time later traffic was worse, not better.
And if you’re going to run busses through the tunnels, you need much bigger tunnels. While the diameter of the Las Vegas Boring tunnels is 12’, that doesn’t mean you can fit a 12’ vehicle in there because it has to have a flat floor, so you lose dimension at the bottom. And obviously since those shuttles are boxy, you also lose dimension at the top so the corners aren’t peeled off.
You could increase capacity somewhat by using mini-vans or similar in an 8 passenger configuration (or less, if luggage is required), but then it’s not much of a luxury ride is it? That doesn’t mean people wouldn’t use it, just that it’s a different sort of transport. Maybe you could increase passenger through-put half-again as much, looking for a 100% boost would be dicey, I think.
Maybe not that many. CES usually has about 150K attendees… it is intentionally spread out to several sites, primarily LVCC but also the Sands/Venetian convention center, the Cosmopolitan convention center and other sites for keynotes, private company meeting sites, foreign exhibits, etc.
Commuting…
And, according to this “Short”, above ground, too.
Is a LLM capable of creating this?
I watched it a couple times, trying to discern if it’s “real” or “AI”.
ralph
I-35 in Round Rock TX has “braided” lanes that significantly improved congestion at “choke points”. Effectively a “bypass” of the choke points.
These are single-lane, limited-access bridges, that wind in a “braid” over n under each other, allowing traffic to flow without “merging issues/ slow downs”.
Is a tunnel just another realization of a bypass around traffic choke points?
Not exactly - it’s not really aimed at that problem.
Why do cars slow down into bumper-to-bumper traffic on freeways like I-35, when there is ostensibly nothing to stop them, from Laredo to Duluth?
One cause: exits and on-ramps. They create “friction” in the flow of through traffic. Exits have lower capacity than the highway itself, they have lower safe speeds, and they are (usually) only on one side of the highway. So you end up with an area where cars are slowing down, merging/changing lanes, and sometimes backing up onto the highway itself.
The braided lanes described in that article appear to be designed to minimize that friction, increasing the capacity and smoothing the flow into and off of the highway.
Fair enough. I was just going off what the interwebs said was the capacity of the LVCC - it doesn’t surprise me if actual conventions don’t max out the LVCC occupancy. Although the websites talk about “participants,” so if you fold in exhibitors and staff and everyone perhaps you’ll have more people on the premises than just the attendees.
Regardless, the point still holds, even if it’s closer to 100K. The Vegas Loop system just isn’t designed to move enough vehicles per hour through the tunnels and stations to accommodate more than a modest fraction of those folks.
Boston’s Southeast Expressway used to have some of those (before the BigDig). Thing was, they have to be 2 1/2 vehicles wide to accommodate one lane of traffic, in case there’s a breakdown to let other vehicles pass, and to let emergency vehicles and tow trucks get to the breakdown past the tie up. Takes a lot of material to make one of those, most of which isn’t used.
Speaking of weird, I guess I’ve searched the word “tunnel” sometime in the past few weeks? This came up on the Facebook feed today for no other apparent reason:
For a month or a year. Then the better travel times will induce people to use that route, developers to build along that route, and presto: same travel time, often worse.
I’m not saying you shouldn’t do anything about it, I’m just saying it’s hopeless. Ho ho ho. Sorry, can’t help it. We’ve been doing the same solution for a century now, you’d think we’d have learned by now.
Indeed. The only thing that’s going to change it is a wholesale change of some kind, and no I don’t think tunnels with modest thru-put is it. That’s a novelty solution, and it’s fun but to really change commuting it’s going to take something wayyyy outside the box.
The pandemic did it (for a while). Work from home could have made a difference if business would have stuck with it. Vastly better mass transit would help but just incremental improvements won’t. Congestion pricing might do it but I’m generally against solutions which disadvantage one economic class in favor of another. Maybe outlaw all traffic or something? Yeah, that would do it.
Ah - I think I understand why we’re talking past each other.
The type of congestion you’re describing occurs at a choke point on an otherwise free-flowing expressway - a spot where everything slows down and clogs, but flows freely afterwards. Spot congestion. Segregating some of the traffic flow from the exits can help with that.
I was thinking of rush hour congestion - when the entire roadway network heading towards (or away) from the downtown/central business district clogs up. In those circumstances, the exits along the route don’t matter. The source of the congestion is at the end of the line, not the edges.
I don’t think you folks understand what is meant by a law of physics. I have driven from coast to coast several times and can say from experience that 90% of the trip occurred without congestion. It is not the case that the presence of asphalt will inevitably lead to overcapacity car use. In most of the country during most of the day, it doesn’t happen. Laws of physics are far more consistent.
Congestion happens because of the way we organize cities, businesses, and transportation options. An example is Los Angeles, long known for its traffic congestion and its dependence on the automobile. Yet during the 1984 Olympics when 650,000 tourists entered the city, traffic congestion virtually disappeared. This occurred because:
Commuters opted to alter their driving habits and work hours and predictions of gridlock never materialized. The exhaustive planning and inter-agency coordination was a success. Not only was the region spared of debilitating congestion, traffic jams were nowhere to be found and the Los Angeles Area enjoyed some of the most carefree commuting in recent history.https://metroprimaryresources.info/hub/los-angeles-and-the-1984-olympics/
I do believe that a subterranean transit system that is financially much easier to expand than a subway and provides similar levels of convenience to a personal auto can be a significant contributor to reducing above ground congestion, particularly as part of a coordinated strategy. I see no reason why a dedicated loop from the convention center to the airport wouldn’t substantially reduce airport congestion during the beginning and ending of large conventions. It is easy for me to imagine how loop tunnels from several peripheral parking lots to Allegiant Stadium would reduce congestion after major sporting events.
A loop that makes it easier to hop between casinos without having to have a designated driver would be very attractive to a lot of tourists. If TBC can really build cheaper tunnels I find it hard to see how the expanded Loop wouldn’t become the preferred choice of tourists to move about the city. That would be a lot of traffic taken off the streets.
The law of physics in question is that passenger cars occupy vastly more physical volume per passenger at times of peak usage than subway cars. This doesn’t matter where there’s lots of space and a small number of cars. It matters a ton when trying to solve for congestion in cities, because cities are space-constrained. Congestion happens because large numbers of people are trying to move into a small space all at once. Not what you observe driving cross country.
Cars take up a certain amount of space per passenger. Too much space for the surface streets of a central business district in a dense metro to handle. So any tunnel going into a dense metro is going to get congested - not because of the tunnel, but because the exit will get backed up. The Holland Tunnel into Manhattan (for example) doesn’t get backed up because the Tunnel isn’t big enough - it gets backed up because that high-volume limited access tunnel eventually opens up into surface streets with traffic lights that have a lower capacity per hour than the tunnel. Hence, the tunnel traffic has to queue.
Building more tunnels to the dense urban area doesn’t create any more space for cars within the dense urban area when they surface. Laws of physics - the cars can’t go somewhere if there isn’t space for them to go. So they have to queue for space in surface traffic, and so the tunnels back up.
If the cars don’t surface - they stay underground and the people walk from the car-tunnel to the surface - then you’ve just functionally duplicated a subway. But with vastly lower capacity than a subway. Again, because of the laws of physics - because the cars take up much more volume per peak hour passenger than a subway car. So you end up having to build large subway-style stations (to accommodate all those vehicles, and all the people, and get them up to the surface) for fewer passengers per peak hour. Which ends up being vastly more expensive than just…building subways.
So you end up with two unpalatable choices. You end up building a more expensive system than subways to move the same number of people and/or a passenger car tunnel that gets just as backed up as every other access. Or you end up limiting the capacity of the system (either one) so that only a small number of people are using the tunnel. Neither is an effective solution for congestion.
Again, all coming back to that “law of physics” - cars fit fewer passengers per vehicle footprint than subways. So in places that are space-constrained, they can’t solve congestion, even with tunnels.
Sure, but Boring tunnels and stations are much cheaper to build and so one can build more of them. It is a question of a few expensive but high capacity subway lines or many cheaper but lower capacity Boring tunnels. One big pipe going from A to B, or many small pipes with multiple destinations. Second, subways are linear, one travels from A to B to C to D with stops at each station. Boring tunnels are not so limited as a taxi can go from A directly to D, with the destinations available increasing as the tunnel network expands. This is more efficient at moving people. Third, Boring taxis only transit when carrying a passenger. During off peak hours, which is most of the day, subways are running at far below capacity. That is inefficient and costly.
If the Holland Tunnel was connected by a tunnel network with multiple, dispersed exit points, the need to queue disappears.
Sweden is building a tunnel network to relieve congestion in Stockholm
The Swedish bypass will relieve arterial road and inner city traffic, and reduce the vulnerability of the Stockholm traffic system. To help reduce the impact on the sensitive natural and cultural environment, 11 of the 13 mile route will consist of tunnels. MSN.
There are also other strategies by which cheaper tunneling can reduce urban traffic that is being explored by other countries. Using tunnels to reduce above ground truck traffic for example.
Japan is contemplating a 300 mile tunnel to move goods from Tokyo to Osaka.
Except when it doesn’t. Many cities are no longer growing in population. Adding more roads, above or below ground need not lead to increase usage when the population is stable or declining. There is precedent:
The Tseung Kwan O-Lam Tin Tunnel (TKO-LTT) is a milestone infrastructure project featuring a dual two-lane carriageway that spans 3.8 km in length, including a 2.2 km main tunnel and a branch tunnel connecting to the Eastern Harbour Crossing. The tunnel has greatly alleviated traffic congestion and reduced journey times by 20 minutes during peak hours. Tunneling towards Tomorrow: Tseung Kwan O–Lam Tin Tunnel
Sure. But I know of no law of physics that says if you create such a space called “a road” it will inevitably become filled with large numbers of people.
Congestion only occurs in certain parts of the country when certain specific conditions are met. That is an empirical observation (see road trip). It occurs when road use is greater than road capacity. There is no Law that states road use will always be greater than road capacity.
You are exaggerating to convince folks that it is impossible to build enough roads (above or below ground) to satisfy traffic demands. But that is only true for areas with growing populations with continually increasing car use. That was certainly the case for urban areas during much of the past century, but today populations in the industrial world are leveling off and in many locations declining. That is the new reality. It is entirely possible to build enough roads in cities with stable populations to significantly relieve congestion. The question is one of economic feasibility, not laws of physics.
But that doesn’t work. Their stations are cheaper because they’re surface lots, not underground (only the LVCC central station is an underground station). Their tunnels are cheaper because they’re too small for high-capacity transport. So “building more of them” means you’re taking up much more space - which in a dense urban environment is no longer cheap.
But congestion happens at peak hours. So if you want your system to affect congestion, it has to have enough capacity to handle the peak. The Loop system keeps costs down by not having enough capacity to affect the peak. If they built enough tunnels and had enough cars to handle the peak, then that capital infrastructure would be completely unused during most of the day. Which is also inefficient and costly.
No, it doesn’t. Because each of those exit points would end up queuing as well. The Holland Tunnel entry into Manhattan actually breaks up into multiple dispersed exit points - but because all of them end up going into the same type of system (a typically-sized Manhattan street with access gated by a traffic light), they end up backing up. The same thing would happen with your tunnel system - each of those tunnel exits would end at a signalized intersection with a traffic light that has to allocate between already congested surface streets and the ostensibly large amount of traffic in the tunnels. So they back up.
Yes - a bypass. As we’ve discussed, a tunnel is an excellent way to avoid a congested destination. That’s not germane to whether it’s a useful tool for travel to a congested destination. The route to the congested destination is limited by the capacity constraints of the destination, not just the route - unlike a bypass, which is going to a non-congested area. But most people are going to where most people are going…which means most folks are going to the congested area.
No, I’m not - you’re misunderstanding both the transportation analysis and the “law” part.
No one thinks a deserted road in the middle of nowhere will fill up with traffic just because it’s there. This phenomenon occurs in congested areas. When roadways are congested, because there are large numbers of people going to a small area in a short amount of time, building additional roadway capacity in one area (like a highway) is usually observed not to have a material effect on congestion.
The reason is simple - if you build a route that’s a faster way to get into downtown (for example), people will shift from all the other routes to get into downtown and use the faster one. And they’ll keep doing that until the new route isn’t any faster than the other ones.
In congested areas, road use is always greater than road capacity at some point on the route. The demand exceeds whatever the constraint is, so there will always be queuing at whatever the constraint point is.
This isn’t a function of whether the city is growing or not or continually increasing car use. The surface grid network of Downtown Manhattan (for example) can only handle so many cars per hour. During peak times, more cars per hour want to get into that area than the surface grid can handle. It doesn’t matter how many tunnels you build to Downtown Manhattan - there’s only enough capacity for X cars to enter and move through that surface grid in an hour, and any more cars than X will have to queue. Whether they queue in one tunnel or fifty tunnels won’t affect wait times - the grid can only handle X cars per hour.
The reason I riffed on your “Law of Physics” jab is because there actually is a law of physics component to this. The reason why roadway capacities are constrained is one of physical volumes. Cars are physical objects and take up space, and cars carry a small number of passengers relative to the space they occupy compared to other modes of transport. Walking is the densest, of course, but modes like buses and subways can move more people into a given space per hour because the vehicles take up less space. So where congestion exists, because you have too many cars trying to get into too small a space in a specific time frame, you can’t solve it by shuffling the cars into different paths into that small space. Because the space can’t handle the volume of all the cars, you need to get the people out of the cars before they enter the space if you want to reduce congestion (or increase the number of people entering the space during that time period given the congestion).
If the transporting population is stable, then the addition of more roads in the congested area disperses the people moving in the congested area. That generally reduces congestion. Simple math.
A sewage system is too small for heavy rainstorms, water builds up (congestion) and flooding results. Enlarge the sewage system enough and there is no flooding. That is physics.
What matters in this scenario is how many tunnels you build within Manhattan. That is what is happening in Las Vegas after all. Tunnels are planned both to facilitate moving people into Las Vegas and to move them within Las Vegas.
Sure it is. A bypass means that those who would previously have to move through a congested area to get to their destination can now avoid that area. That will reduce the traffic going into the congested area. No reason why that impact cannot be significant, unless you have another idiosyncratic Law of Physics.
The Swedes back me up. From the Swedish link:
"When complete, the bypass will not only relieve congestion in the city centre but also reduce impact on the environment and surrounding residential areas. "
But tunnels don’t add more roads in the congested area. They either add more roads leading to the congested area (tunnels that open up to the surface so that cars have a different route into the congested area), or they operate like subways and bring people to the surface roads on foot through stations. If the system is the former, the tunnels will get just as congested as any other roadway.
If all your sewage system has to go to the water treatment plant, and you enlarge your sewage system but don’t increase the capacity of the treatment plant, you’ll still get flooding. Because it’s the treatment plant that’s the bottleneck - not the pipes in the streets.
(Minor quibble - sewage systems usually only carry human waste. Rainfall is moved by stormwater systems. Sewage systems are invariably designed to keep rainwater out. Same principle holds, though - if your stormwater system only goes to a single outfall, it doesn’t matter how many pipes go to that outfall, the capacity of the system is limited by the capacity of the outfall).
No, it doesn’t. If every tunnel has to access the surface, then the capacity will still be limited by the surface roads. If the tunnels don’t let cars have access to the surface, and only the people do, then you end up with a subway system.
Again, most people are going to where most people are going. Bypasses help - I noted that at the top of the thread - and especially for cargo. Here in Miami we build a huge tunnel to get cargo traffic out of the Port, which is located right next to Downtown (as was useful back in the 1900’s) so that the trucks can get right on the highway and not go through downtown.
But that’s not what the Loop is, either in implementation (in Vegas) or description (Musk’s musings). It’s not a bypass - it’s a transportation network within an urban area.
