this post was submitted on 30 Sep 2023
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Yeah and the big road below can hold WAY more than 10,000 too. The numbers here are all made up and it doesn’t really do a good job of making the point the creator wants to make.
Yeah.
I think I count 23 lanes in the bottom pic.
Ignoring the effect of heavy vehicles and assuming a free flow speed of 70, the federal highway authority's numbers would be 2400 vehicles per lane or 55k vehicles per hour. Assuming an average occupancy of 1.5 people per vehicle, that's nearly 83k.
I'm having trouble finding actual sources right now for max rail capacity, but https://en.m.wikipedia.org/wiki/Passengers_per_hour_per_direction claims 60-90k passengers per direction on 3.5 meter lanes for "suburban rail".
Although 83k people per hour is 41.5k people per rail track. Assuming a 360 person train like the Bombardier BiLevel Coach, that's only 115 train cars per hour per track. If each train has 11 cars, that's 10 trains per hour or a train every 6 min. Not really that unreasonable, and the tracks will look mostly empty unlike that monstrosity of a road.
The road in the bottom picture seems to be jammed. 23 lanes are no use if there's a bottleneck at the end.
That's by design, and helps make the case for MOAR FREEWAY$$!
https://en.wikipedia.org/wiki/Induced_demand
That photo looks like the 26-lane wide Katy Freeway in Houston! I use the rule of thumb of 2000 pphpd (passengers per hour in peak direction) for a fully-loaded freeway lane from this much better-looking graphic we saw last time we discussed this question on lemmy. (Apparently this graphic is now the headliner on the pphpd wiki page!)
2000 pphpd per lane matches my own attempts to verify this value. I couldn't find traffic stats for Katy Freeway, but here are the stats for Manhattan river crossings: https://www.nyc.gov/html/dot/downloads/pdf/manhattan-river-crossings-2016.pdf Specifically, the George Washington Bridge is a very busy bridge with 7 lanes in each direction and highly-optimized traffic density - constant traffic flow with no spacing in between - a good example of peak highway lane capacity IMO. It moves 290k vehicles per day, but more importantly 11k incoming vehicles during peak morning rush hour (page 10), which is 1600 vehicles per lane. The average occupancy is 1.74 (page 24, though not sure how that treats buses), so that's 2800 ppphd per lane.
GWB does have a lot of truck traffic though. The Holland Tunnel has 2 lanes in each direction, no trucks, constant traffic flow with no spacing, 2700 inbound vehicles during peak morning rush hour (page 10), and 1.22 occupancy (page 24), resulting in 1600 pphpd per lane.
So that's
2739*1.22 + 4860*1.41 + 11474*1.74= 30k people crossing from New Jersey into Manhattan during the morning rush hour using the 2+4+7=12 lanes of the Holland+Lincoln tunnels and GWB or 2500 pphpd per lane. I believe that sufficiently approximates 13 lanes of Katy Freeway, which has no trucks and no buses.Compare that to the 22k people transported from New Jersey into Manhattan during morning peak rush hour by PATH trains in two incoming tubes (https://www.panynj.gov/content/dam/path/about/statistics/2023-PATH-Hourly-Ridership-Report.pdf page 14, only shows turnstyle entries but almost everyone entering is travelling to Manhattan). And PATH trains look outright empty compared to crowd crush on NYC trains. Lexington Avenue Subway is like 32k pphpd for a single express track (https://new.mta.info/document/22126 page 5B-4,
25*1296in 2002 and has gone higher since).In conclusion, the numbers in this meme photo do not reflect full capacity, thus leading to questions and confusion, but the overall comparison is still valid: one half of a 26 lane highway has about the same capacity of ~30k pphpd for peak hour travel as one half of a 2-track railway.