u/ArcaneDemense

I've been reading debates about using agro-forestry for efficient land use, healthier diets, and significantly reducing outside inputs, plus trading consistent year round human labor for high mechanization and crunch time harvesting practices.

According to various people trying to provide alternatives to row cropping and using some detailed math regarding growing times it seems like it would be possible to average 10 million calories per acre with a proper combination of food and wood/shade/water management trees, calorise dense crops like potatios and rutabaga, middle area crops like carrots, proper seasonal planting and so on while allowing for highly controlled chicken and sheep grazing.

Not only would you be doing location rotation yearly but running different crops all year round in each planting area, plus mixing with trees and crops which are not planted fresh yearly. There also seems to be a large benefit to growing mushrooms and other things which help create superior soil and nutrition.

Some models also seem to use light rail transport to save space, and support human labor focused harvesting and management, while avoiding MPK, pesticides, and herbicides.

Additionally if you were to avoid long distance transport and consume products within a small geographic area, for instance attaching a large agro-forest to specific high density city, you could even grow a variety of plans that were not optimized for transport over flavor and nutrition.

Additionally it seems to be the case that there are many plants especially herbs and shrubs, which were part of historical food growing which produce both nutrition and provide benefits similar to cover crops and nutrient management, which would assist in raising caloric density while also providing value for other plants, especially if you had a dense mycelium network.

How plausible is a high calorie agro-forest that covers a large area between 10 km^2 and 10,000 km^2?

Although maximizing calories per acre or per man hour or for efficient machine management can be valuable, it seems like there's a lot of trade offs where a moderately less productive, more human labor intensive method of agriculture might create value by trading for better micro nutrients, avoidng expensive industrial additives, not having to own expensive diesel machinery, avoiding pesticides/herbicides, and providing more availability of healthy components of a culinary system.

Plus agro-forestry seems to provide substantial value in creating stable year round jobs and reducing high intensity peak harvesting periods.

There's also some evidence that an agro-forest can start with more marginal land, which it improves as it fills in and eventually turns into high quality land with good water retention/access and superior soil.

The vast majority of modern urban centers, including the city of NYC and the Ville De Paris, spend ~35% of their total land area on transit. If you removed cars, stroads, parking spots, parking lots, parking garages, and car infrastructure like auto-shops and gas stations, you could reduce total transit use, including bikes and walking, to 10% of land area. That gives you an extra 25% of the total land area of any modern city for whatever you want.

Suppose we built a city from the ground up without cars and with a focus on local community, free transit, and sustainability and human health.

Say we wanted to provide for 10,000,000 people, so moderately larger than NYC.

We could take a land area of 500 km^2, roughly 62.5% the size of NYC, and we could use only 1, 2, and 4 family buildings, with roughly 500,000 single family homes, 500,000 2 family buildings, and 250,000 4 family units, and 8% of land area greenways for walking and bikes, plus accesibility vehicles, plus 2% of total land area in grade separated electric rail. So our total transit usage would be 50 km^2 of land or 10% of total land area.

Our residential land use would account for roughly 50% of total land use and this would account for neighborhoods all being built around a central park area with a local elementary school inside it.

We would thus have 40% of our land area for public green space, public infrastructure, commercial area, and industrial area in whatever proportion was necessary or desired.

Now you may argue that we should use denser residential structures and I understand the reason, but the counterpoint is that urban land area is not actually the constraining factor in land use. It is agro-forest land area, roughly 10 km^2 of agro-forest for every 1 km^2 of urban area. Packing in more density in the urban area is totally doable but you'd need to greatly expand the ageo-forestry area to keep people fed.

Without cars you could feasibly have densities as high as 80,000 people per km^2 but you'd need 4x as much agro-forest per km^2 or urban area to feed all those people.

I should also note that car related land use is even worse in suburban areas, particularly in the United states. Luckily under a car free model suburbs would not be necessary because you could have a decent "single family home" in the dense urban area.

If you asked a typical urbanist, the kind of person posting on r-transit or r-urbanism, they would try to argue with you that you couldn't use this housing model in a city as dense as modern Ville De Paris, the most central urban core of Paris, or in the 5 burroughs of NYC. But they would be dead wrong. Fun fact, Manhattan is ~50% car usage and public pavement, which is much worse than the NYC average. Horrifying to think about.

Tangentially related, if you built your agro-forest fed city in a state like Nebraska you could provide 100% of your energy needs through wind from turbines above the aggro forest, and solar in the agro-forest and in your city itself. You may even rely on artificial closed loop pumped hydro power to store energy instead of batteries.

Important Notes About Already Covered Or Recurring Objections:

Yes *you can* in fact have 20,000 per km2 density with 1/2/4 family homes and above average children per family. The math absolutely works. I saw a lot of people in other places insist that it couldn't, some were willing to admit they didn't actually try it but were going on intuition.

Yes *you can* supply 50,000,000 people using 10,000km of tram tracks arranged in a grid which compliment greenways that support bikes and walking. Logistics is viable for food and commercial goods like clothing and appliances.

A typical modern major city has roughly 25%-35% of raw land usage dedicated to cars + any public transit. A city with 0 cars can support 20,000 people per km2 population densities using only 10% of overall land.

It takes roughly 25,000 km2 of contiguous agro-forest to support 2,500 km2 of urban area with an average density of 20,000 people per km2. You could get this number down to 20,000 km2 if you were willing to make some tradeoffs on what you grew and take some hits on non-food crop production.

Main Post

Imagine a city optimized for raising children and avoiding harsh environmental impacts.

I'm from the Midwest so we'll call it a GrunKinderStadt. People here are quite invested in their German-ness relative to the rest of America.

The city covers 1,500 km2 of neighborhoods centered around a park-like area with an elementary school inside. Each housing "bubble" contains 40 homes, 20 duplexes, or 10 quadraplexes. Note that the structure/format/layout of the building is not based on standard dwellings. Each family has an average of 5 kids, if we assume the city has finished construction and been active for say 10 years.

10% of all land area, so about 250 km2 is split between 200 km2 of greenways designed for cars and bikes, with "arterial" lines capable of supporting European style emergency vehicles, and 50 km2 of tramways in a grid with 25 north south and 25 east west line with 4 tracks each, two each way, with the outer two tracks going opposite ways for standard 25km/h service at every 1km stop and the inner two tracks going opposite ways for express 50km/h service stopping every 2km.

Interior tracks are lowered a bit from ground level at stops and stop every 2km while exterior tracks are raised a bit above ground level and stop every 1km. Passengers for interior tracks walk down a ramp such that the two tracks don't interfere with each other.

Each track is separated from parallel tracks by 2km and perpendicular tracks cross at an offset such that every 2km stop station for the fast rail connects to a perpendicular tram line for efficient switching.

Utilities run underground along tunnels although surface level utility access is possible for city vehicles designed to travel along the bike/walking paths similar to the emergency vehicles with a different light/sound combo alerting normal users of the approach.

Dense commercial areas would account for ~250 km2 of land.

Industrial areas would account for ~250 km2 of land.

Schools for higher grades, universities, and major public buildings like hospitals, fire stations, and police stations plus neighborhood level commercial buildings would account for the final 250 km2 of land.

In this particular hypothetical of the GrunKinderStadt, the "green child city", 10% of the population, well 20%-25% of working age, would be engaged in work in the 20,000km2 of agroforestry land. That's the necessary amount of land to product food for 50,000,000 people with a labor rate of 1 worker per 10 humans. A single square kilometer of medium age agro-forest can feed roughly 2,500 people.

As the design of the city is focused on raising healthy children at above population replacement rates, roughly each family would average 3-7 children over their lifetime, having a local supply of diverse and healthy food inputs, as well as a significant reduction in gas/tire/plastic pollution is a core goal. That's a primary reason for the no car stipulation.

The following spoiler contains information on transit capacity and how the tram system can handle the necessary usage for so many people:

>!Transit capacity explanation/extra details, plus some school theory:!<

>!So using a 50mil pop number, you've got ~20 million working age adults.!<

>!Some significant portion walks to their jobs, another subset bikes. Leaves remaining group for trams.!<

>!Trams have a peak capacity around 2,000,000 at a time.!<

>!You have 4 shifts, although the 2 day-time shifts probably account for 70% of workers with only 30% on the night time shift, mostly for essential services. And given the school timing patterns we probably see it as something like 40% first shift, 30% second shift, 10% night shift, and 10 early shift.!<

>!So out of 20,000,000 people you are looking at a maximum of 8 million at a time heading to work but likely less due to staggered starts.!<

>!25% of working age adults work in the agro-forest, so 5 million, they leave earlier and quickly move from the trams to the agro-forest train lines for the rest of the work shift.!<

>!School hours would be something like 8AM/9AM/10AM for elementary school, middle grades, and late grades, roughly half the kids start at 8, so the same for school employees. You've got 25 million school age children according to the model in the post for a 50 million person city. 14 million go to school at 8AM, and at a ratio of 2 adults per 10 children that's 2.8 million adults at 8AM. Then you've gote 7 million kids at 9AM for the middle grades, and then 4 million for 10AM for the older teenages. So 1.4 million adults and 800,000 adults at those times, so 5 million of your 20 million workers.!<

>!There's some variance for school breakfast programs and/or before school programs but we'll ignore that even if it makes the numbers more favorable.!<

>!So out of 20 million workers we have 5 million leaving around 6AM for the agro-forest, 2.8 million around 7AM for elementary school employees, 1.4 million around 8AM for middle grades, and 800,000 around 9AM for higher grades.!<

>!That's half our total and given that many/most elementary school employees are walking or biking because there is an elementary school per "neighborhood" with 80-120 students and 16-24 employees, we can say that maybe 80% of elementary employees are not taking a tram more than 1 stop if at all.!<

>!Schools for older kids are larger due to the need for more specialized instructors and resources/infrastructure and they have fewer grades so they can fit more neighborhoods worth of kids/employees into the same space, probably 50% or more of those employees need tram access for more than 1 stop.!<

>!Then we've got to look at city employees, *including tram/transit staff*, which would have to arrive at work around 5:30AM to take over from the nightshift and sure capacity for the argo-forestry rush at 6AM.!<

>!Second shift starts going to work about an hour before first shift ends, and both the people going in and those returning home are somewhat staggered, so you end up with ~2 peak hours and 2 non-peak hours, rather than one massive rushhour.!<

>!First shift is something like 7AM to 2PM, second shift is 1PM to 8PM, third shift is 7PM to 2AM, and fourth shift is of course 1AM to 8AM. There would be some variation by an hour either way based on the job I suppose. School is 4 days a week, most jobs would also be 4 day weeks with a variety of what days would be worked.!<

>!So you'd have pretty even hourly usage of trams. And of course walking and cycling paths don't really have a capacity issue. Of course aside from public sector jobs and the agro-forest most jobs wouldn't be perfectly organized in a centrally planned way but from my math there's plenty of breathing room regardless.!<

My main goal for this post is to get strangers to weigh in on major problems with my design. I do have answers to lots of potential questions but it wouldn't be reasonable to pre-respond to every possible suggestion of issues, so I limited the top section to very common answers.

Note: I know there are many concepts related to national high speed rail but it typically seems to me that their model usually involves much more direct routes into major cities which is insanely expensive and I think an inferior model to my suggestion.

A major problem with adding high speed rail is the tight geometric tolerances coming into conflict with geographical and political barriers, especially around coastal eastern cities.

If you follow the "ideal route" for a train line connecting the 40 densest/most populous cities from Boston down to Atlanta, including Richmond, Raleigh, Charlotte, and Columbia in the southern stretch, there seems to be a very viable "offset route" which is fairly optimal for the geometric limitations of high speed rail lines hitting 250 km/h or more.

If you had peel-off and merge-in lines from the relevant high population areas it seems like you could reap most of the benefits of high speed rail with a very reduced downside, saving tons of money and tons of fightng with nimby forces.

The straight line distance is ~1,500km but you'd probably be at more like 1,750 km counting the main offset trunk line and the connections for ATL and Boston.

You'd be competing with about 4-5 hours of time for flights due to the delays of air travel on top of the actual air time.

It seems likely it would take about 8 hours total to go all the way from Boston to Atlanta by train.

It would take about 17 hours by car assuming you went straight through.

You'd be paying approximately $132 for gas, plus some value for the extra 9 or 10 hours vs the train. Plus you'd personally have to do the work of driving and there are other potential costs like hotels if you, very reasonably, split the trip in half.

For the provider there would be significant administrative savings, although of course maintaining tracks would be expensive.

If the ticket price for one way could be brought down to $10 per 100km traveled this would be a valid alternative to driving along the length of the rail line, putting you around $180 for a Boston to Atlanta trip.

If a group, say a government funded independent entity, were to buy the rights to the land for this amount of rail, they'd likely be able support ~4 separate travel lines which allows for easier scheduling as well as maintenance and potentially military uses which shares the cost overall. Dedicated passenger lines would significantly improve the value vs sharing with private freight lines.

There are of course downsides to an "offset trunk" model but I think that especially in the case of lowering costs for construction and enabling tracks with geometry optimized for high speeds, they are easily less penalizing than the upsides.

From a government infrastructure development perspective there would actually be a lot of positive externalities like lowering highway and airport congestion, environmental impacts for those who care about those, lowering highway deaths, and so on.

The estimated cost would be south of $200bil, potentially much lower, which would make it far cheaper than the current rail projects in California.

Additionally having a large core network to tap into for other regional rail projects, a market for many more trains to lower the per unit cost after accounting for the starting capital, and many other factors would provide value well beyond the direct impacts.

There are also several other high potential routes such as turning west beyond eastern PA to connect major industrial center in Western PA, the major Ohio metros, plus Detroit, and Chicago as well as a southwest split from that route to hit Columbus, Cincinnati, Indianapolis, Louisville, St. Louis, Kansas City, and Omaha.

These extensions would end up being massively cheaper as the workforce was built up to handle the earlier more difficult routes and the concept was proven.

A third phase might run routes from the major Texas metros up to Tulsa OKC, Wichita, KC, Omaha, Des Moines, and then the Twin cities.