Not that there needs to be a formal regional government. The US has interstate compacts for situations like this. https://en.wikipedia.org/wiki/Interstate_compact even comments "these agreements create a new governmental agency which is responsible for administering or improving some shared resource such as ... public transportation infrastructure".
It helpfully links to https://www.csg.org/NCIC/MidwestInterstatePassengerRailCompa... - "the Midwest Interstate Passenger Rail Compact brings together state leaders from across the region to advocate for passenger rail improvements. Formed by compact agreement in 2000, the compact's current members are Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota and Wisconsin."
and http://www.drpt.virginia.gov/rail/major-initiatives/va-nc-hi... "The Virginia-North Carolina High Speed Rail Compact was authorized by the Congress and established through legislation enacted by the Virginia and North Carolina General Assemblies. The purpose of the Compact is to examine and discuss strategies to advance multi-state high speed rail initiatives."
+ A fine grained passenger rail network still requires about all the roads we have now. The local restaurant needs a pallet of french fries not a boxcar's worth.
+ Neither of the example compacts has executive authority over the participating states. Advocacy and study, only. They only allow states to coordinate efforts with respect to federal programs. MIRPC can lobby for continued Amtrack support [1]. It can't obtain right of way and lay track.
[1]: http://miprc.org/News/miprc-to-congress-fra-amtrak-sustain-t...
An express limited service in the 1940s did not benefit most residents, compared to a local service, in a similar way to high speed service now.
My example of those two compacts was to show that supra-state organizations can exist with transport goals in mind. As examples of more effective compacts, the Great Lakes Compact.
There is no need for executive authority over participating states. International agreements occur between different countries even without an organization with executive authority over those countries.
Case in point: the Basel tram network provides international service, which started in 1900 with service to the German Empire. Wilhelm II didn't have executive authority over Basel, nor Switzerland over then-Sankt-Ludwig.
pIN = pS(1) x pS(2)...pS(n)
+ The Great Lakes Compact is legally binding. It required approval by each state's legislature. To me, the politics are radically different. The compact prevents states from damage by other states. It exists to avoid a tragedy of the commons where people may die. Rail networks don't have that.
+ I considered diving into the differences between the 1940's and today as they relate to passenger rail networks in my previous comment.
Local passenger rail isn't viable because most rural communities have much lower populations today than in the first half of the 20th century and because transportation alternatives are much better in rural areas. Hopefully, we agree on the second point.
The demographic shift in rural areas has a strong labor component related to mechanization of agriculture. In the midwest, a farm family in 1920 could work about a quarter section of corn (160 acres). Today a family can work about two sections (1280 acres). A small town rail station in 1930 might have served a township with 3000 residents. Now it might serve 1000.
In the South's cotton country, the demographics are even more substantial. In 1940 a share cropper family could work about 20 acres. Mechanization moved major cotton production to large fields in places like Texas. The twenty acre fields were mostly converted to timber and the share cropper shacks left to decay. Small towns that once were the center for several thousand locals are now empty buildings with a few hundred locals nearby.
Local rail in rural areas is economically untenable. The express trains of 1950 worked because there were finer grained networks feeding it. Today, the fine grained network for rail is the same as for air and automobile. It's the automobile.
That's why intrastate high speed rail isn't being built. The proposed Orlando-Tampa route still required a car to get from Azalea Park to the Orlando station and another car to get from the Tampa station to Clearwater Beach.
+ One of the major tradeoffs between rail and auto transportation is scheduling. Scheduling trains efficiently is a job-shop problem and is NP-hard. Adding efficient public transit at each end of the Orlando-Tampa line to avoid the need for an automobile adds terms to an already exponential scheduling problem.
The way to mitigate latency in scheduling problems is not cleverness. It's adding substantial surplus capacity to smooth out peaks. It's making the system generally inefficient. Amtrack's poor level of service is a natural result of focusing on efficiency. High speed rail systems designed around efficiency will not beat the mathematics. Nobody is making a high speed rail case around high availability because it's politically infeasible.
It's probably economically infeasible as well. Rail is a circuit switched network. If it is designed to handle 1000 passengers per hour, handling 1001 passengers takes two hours not 1.001 hours.
At the state level, a high speed rail will never benefit most residents. For example, a "northeast corridor" line is great for Philadelphia, Manhattan, and Boston. doesn't do anything for the citizens of Pittsburgh, Albany, and Springfield.