A M/V merge isn't good for various reasons. I mentioned this plenty of times and people overlook it.
The Queens Blvd line needs a full train set.. particular the 53rd Street corridor needs it the because of where those exits are.
The amount of service that is needed on Queens Blvd isn't necessarily needed on Metropolitan Avenue. This is complicated by a train crossing in front of major traffic. Reducing service to accommodate this arraignment just won't do.
People will continue to use the "L" because it is more direct and it connects with all the lines in Manhattan. A M/V merge doesn't come close to that.
And.... A passenger traveling times on the M/V merge will actually increase due to slower speeds because of multiple curves and switches. Forget about the fact that it now has to wait for a merging "F" train.
Talk about offending Metropolitan passengers... This is just a spell of disaster. Queens Blvd lines experiences delays quite often due signal issues and broken rail. It just not a sound idea!
And most of all, it will eliminate the possibility of creating a more favorable express service via culver. There are proposals on the table right now to introduce this kind of service. What do ou say to those passengers?
just for fun i will refute these as requested
* QB needs a full train set:
already refuted, V trains are nowhere near full due to the "expressaholic" nature of queens residents.
* service amounts differ on QB local vs. metropolitan;
* QB line has many delays:
you can have some M/V's from QB still terminate at 2nd avenue. this would allow for proper headways along broadway in brooklyn as well as allow for flexibility in which trains leave their terminal at which times. e.g., if there are delays on QB (result: fewer TPH reaching 6th av) you can send more of the trains down to metropolitan - then on catchup more will terminate at 2 av to thin out service along bway bklyn again.
* M/V merge is not as useful as the L:
the only trains that the L can transfer easily to that the V cannot are the 4/5/6 (below 51st), and those riders can transfer to a J for that (or use SAS of course, if that is ever built). or of course you could just transfer to the L as you used to, an M/V would not eliminate this option
* M/V's will run at slower speeds due to track crossings:
i am not convinced of this, there is just one extra merge in either direction.
* it will destroy the chance of a culver express:
this is just not true, you can very easily have an <F> or the like without needing the V (see below).
now, all i need is an emoticon of someone beating a dead horse...
some related ideas...
i've stated elsewhere that the best way to make up for the loss of M on west end service is to extend some W trains rush hours (this is again flexible because you can send just as many trains down that line as you need, and terminate the rest at whitehall).
for F express: trains on the local tracks can turn around after church avenue without any crossovers - this is how the G would turn around when it is extended there. so you could have a V (assuming the M/V is called the M) that would terminate at church daytime and go local up to manhattan (where exactly is a point of discussion, although it is probably needed on QB exp, perhaps it can go there via 53rd depending on service levels). then the express F would skip bergen, carroll, smith, 4th, 15th, and fort hamilton pkwy and continue on to coney island via local.
you could also do some wacky stuff at this point like run G trains via express from 18th and terminate at kings highway (skipping I, bay pkwy, N and P). it would depend on how much service is needed along the culver branch (but from my experience PM rush the train basically empties out at 7th)
the alternative to the plan 2 paragraphs above is to have the express terminate at kings hwy, and run only in the peak direction from KH to church. what i prefer about the above though is that express service is generally most useful for those that live further out, so you would want coney island passengers to be able to use the express without a transfer.
and that's my spew for this evening...