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They have taken this approach in my city arguing improving the road network will not improve congestion and if anything reducing the number of roads is what's n

• MereInterest 5y ago
  There's a number of key differences, mostly in how things scale with increased use. * Car transit is typically scaled through increased space allocation. Public transit is typically scaled through increased utilization of the same space. * Car transit is limited at about 2000 vehicles/lane/hour. Public transit is mainly limited by the number of buses/trains on a route. (e.g. A typical bus can carry 30-100 people. Replacing a lane of car transit with a dedicated bus lane drastically increases the throughput of that lane.) * If the number of highway lanes are doubled, followed by induced demand using that capacity, the result is a much less enjoyable experience driving. If the frequency of buses doubles, followed by induced demand using that capacity, the result is a much more enjoyable experience taking the bus, as the wait for the next bus is shorter. * There's a phase transition in public transit utilization that happens when buses/trains/subways arrive more often than once every 15 minutes or so. If a bus arrives once every hour, you need to carefully plan your day around that particular bus, arrive early to make sure you don't miss it, and waste a lot of time waiting. If a bus arrives once every 10 minutes, there's no need to plan ahead, and you just get on whichever bus arrives next. The Youtube channel "Oh the Urbanity" had a pretty good video on induced demand as it applies to both car transit and public transit [0], that I highly recommend. Most everything by the "Not Just Bikes" channel [1] is also pretty good. [0] https://www.youtube.com/watch?v=8wlld3Z9wRc https://www.youtube.com/watch?v=8wlld3Z9wRc [1] https://www.youtube.com/c/NotJustBikes/videos https://www.youtube.com/c/NotJustBikes/videos
  • kypro 5y ago
    Thank you so much. That video basically addressed my exact confusion! The internet is amazing. I think I'm correct in thinking this paradox does apply to other modes of transport such as subways, but that by itself doesn't mean that we should therefore build more roads because in general infrastructure spending would be better allocated to other modes of transport for numerous reasons. I do agree with that argument, but it seems there would be nuances there. I'd agree it's generally more efficient in the inner city, but less so as population density decreases. In areas with low population density the car is probably by far the best mode of transportation and there its use should probably be accepted. I think my confusion comes from how it's often sold as a black and white thing politically where, `car=bad` because this clearly isn't true as general rule. If the argument is simply that within densely populated areas the use of public transportation should be promoted over extra capacity for cars then I completely agree, but where I live I would argue some questionable city planning decisions have been made. Specifically, lanes have been removed from roads to make way for bike lanes and speed limits have been reduced almost universally. While I'm all for promoting cycling these bike lanes go almost entirely unused because it's very hilly and things are too far away for cycling to be a practical mode of transportation in most cases here. In this case the pros and cons don't appear to add up and I suspect the city planners are probably just out of touch with the differing transportation requirements between where they are in the inner city and in areas such as mine.
    • MereInterest 5y ago
      I think that frequently, a city will be so optimized for cars that (1) no other infrastructure can effectively work around it, and (2) any changes away from that optimized solution feel aggressive toward cars. For example, consider curb radius at intersections. The smoother the curve, the nicer the experience for cars. If you can take the turn at 35 mph, then you don't even need to slow down. The car behind you doesn't need to slow down as you turn, and it's altogether more enjoyable to drive. But that means that the intersection is much larger, to accommodate the smoother turn. That means cars are making a right turn at higher speeds, leading to more dangerous collisions with pedestrians. And this happens for pretty much every tradeoff. That might be why you see it as an impasse between different groups, because either tradeoffs need to be made, or the overall cost goes up significantly (e.g. moving all parking spaces underground). * Bike lanes are adjacent to car traffic, decreasing usage. We could have separated bike lanes, but that space was already used for more car lanes. * Bike lanes take circuitous routes, increasing distance. We could have more direct routes, but that space was already used for wide roads. * There's no walkable area in the city center, because the shops have large set-backs, and are spaced far from each other. We could have storefronts closer together, but that wouldn't allow for as much parking space. * Bike parking is rare, and typically pretty far from your destination. We could have bike parking at every storefront, but that would require cars to be parked further away. (Though, given that you can fit 10-15 bicycles into a single car spot, the impact even there would be minimal.)
• thaumasiotes 5y ago
  > For example when subway systems don't have enough capacity doesn't this paradox apply? Not really; Braess' Paradox is about adding edges to a graph, but subway expansion usually doesn't work by digging new tunnels between existing stations.
• adrianN 5y ago
  If cars had no externalities just building more and more roads would probably be a good strategy. But cars have high externalised costs. There is of course the environmental aspect and accidents, but, perhaps less obvious, due to poor space utilization, more car infrastructure makes cars all but required since density becomes so low that walking or cycling are right out and public transport has no chance of being remotely cost-efficient (or convenient, who wants to walk ten minutes through a parking lot to reach the store after getting there by bus?)