Not that tunnels are a boring idea, but if you handed me a couple of billion, I think we could solve public transportation using ultralight above ground systems. I would base it on a roller coaster type design using single or dual tracks suspended by high load anchored polls.
The car weights would be kept to a minimum, allowing tracks and supports to be sized much smaller, lowering cost and design requirements. The average car would weight less than a bus, and could travel at very high speeds.
Existing trains and subway systems are based off of hundred-year old freight train systems which were designed to transport thousands of tons of weight. This has a huge cost for subway and commuter train design. A modern subway train costs millions of dollars, weighs multiple tons, and is an immense engineering task.
By engineering a total target track and car weight of a few tons per spacing instead - this system would be far cheaper and easier to maintain.
Passenger cars would be designed to hold only a dozen people, and cars would be linked or unlinked as needed to increase capacity and efficiency. This design also allows the system to maintain extra cars of varying sizes to manage variable rider capacity. Rather than time tables, the system would run based on rider demand, maintaining a slight over-capacity to handle peaks. This is no different than the typical Uber-type demand based system.
On the typical street, such systems would only utilize a few square feet of space per block. They could also utilize existing utilities and would require minimal space for stations. Trains would exit the main track to prevent stalling the main rails while boarding passengers.
This system could also be extended to long-hail service as well into suburbs, or perhaps across states, It wouldn't have nearly the same difficulties of property right of way, environmental impact, and NYMBY - as it essentially has about the same impact as a typical electrical infrastructure. It could also be placed along existing roads and bridges to quickly build out the system.
The car weights would be kept to a minimum, allowing tracks and supports to be sized much smaller, lowering cost and design requirements. The average car would weight less than a bus, and could travel at very high speeds.
Existing trains and subway systems are based off of hundred-year old freight train systems which were designed to transport thousands of tons of weight. This has a huge cost for subway and commuter train design. A modern subway train costs millions of dollars, weighs multiple tons, and is an immense engineering task.
By engineering a total target track and car weight of a few tons per spacing instead - this system would be far cheaper and easier to maintain.
Passenger cars would be designed to hold only a dozen people, and cars would be linked or unlinked as needed to increase capacity and efficiency. This design also allows the system to maintain extra cars of varying sizes to manage variable rider capacity. Rather than time tables, the system would run based on rider demand, maintaining a slight over-capacity to handle peaks. This is no different than the typical Uber-type demand based system.
On the typical street, such systems would only utilize a few square feet of space per block. They could also utilize existing utilities and would require minimal space for stations. Trains would exit the main track to prevent stalling the main rails while boarding passengers.
This system could also be extended to long-hail service as well into suburbs, or perhaps across states, It wouldn't have nearly the same difficulties of property right of way, environmental impact, and NYMBY - as it essentially has about the same impact as a typical electrical infrastructure. It could also be placed along existing roads and bridges to quickly build out the system.
Anyway - just an idea.