How to close down NYC subway from 12AM-5AM without shutting down mobility for commuters

Recently the RPA published a report suggesting ending 24/7 service for the NYC subway. The MTA and city officials responded that it was not an option because commuters need to be able to travel during these times in the City That Never Sleeps. True enough, but can't we find a compromise to this?

Data suggests that demand between 12AM to 5AM is on the order of 85K riders in that time interval on weeknights, compared to a daily average of 5.7M riders. That is about 1.5% of the daily ridership. The NYT article supports this as well.

(source: https://psravanthi.github.io/MTA-New-York-Subway-Traffic-analysis/)

How many vehicles would we need to serve this demand on the surface roads? Based on a study by Alonso-Mora et al. (2017), a fleet of 3000 on-demand vehicles with capacity of 4 passengers can serve up to 3M rides with an average wait time of 2.7 minutes.

(source: Alonso-Mora et al., 2017)

If we consider Via service or shuttle buses with capacities of 10-15 passengers, can we not achieve station-to-station delivery at off-peak times at a substantially lower fleet requirement (and hence cost)? Via can already provide such Manhattan service door-to-door at a fare price of $5 per passenger (which is only $2 more than a subway fare). If so, then I suggest the following:

PROPOSED IDEA FOR MTA TO CONSIDER

What if we close Manhattan lines only during 12AM-5AM on a regular basis? Keep the other lines out of the boroughs up except for scheduled maintenance. MTA would provide subsidized service guarantees using a service like Via or a similar shared-ride shuttle bus only for trips made within Manhattan from one subway station to another as an MTA fare. People who need to travel into or out of the borough would have to take the subsidized service to a designated gateway station that continues to operate lines out of the borough.

By requiring only pickups and drop-offs at existing stations, the operating costs can be reduced with more efficient routing and repositioning algorithms. Using Via vehicles with capacity of 4 or shuttle buses with 10-15 passenger capacity, we’ve seen the cost would be much less than 3000 fleet in the Alonso-Mora paper (since the demand would be much less and vehicles more flexible if operating with 10-15 passenger capacities). Trips during those hours would be under less congested conditions as well. 

Outcomes:

-         Passengers making trips within Manhattan between 12AM-5AM would not have to pay any more, while trip time would potentially be shorter (for shared rides passengers may end up stopping at several other stations using dynamic routing algorithms).

-         Passengers entering and leaving Manhattan to other borough stations at those times would have to endure one extra transfer. On the plus side, lines operating in other boroughs can have much shorter routes (e.g. N line would not have to enter Manhattan from Brooklyn) and would be much more reliable and may even reduce headways at those times.

-         MTA would save on costs of operating the Manhattan subway lines without compromising mobility at those times, so we would still be the City That Never Sleeps.

-         The savings can be used to better maintain the lines so that their operations during the day would be more reliable. It would also help the MTA to usher in the new signal upgrades and CBTC infrastructure faster than their current timeline.

Thoughts about this proposed idea? Feel free to comment below.