In almost all cases, bus service would be much slower, and you have to fight the perception of bus service in general in this country. I predict such weekend replacements, done on a permanent basis, would last about as long as late night service before hitting the chopping block.
This is at least the second, perhaps third (my memory is fuzzy) time in the last decade that weekend commuter rail service has been on the chopping block. I think this helps solidify the perception that "it just can't be done" or "it'll never work here" without examining any of the real issues involved:
-could service be scheduled better to enhance ridership?
-are fares and parking costs set right to attract weekend usage?
-how can trainsets and crews be used more efficiently on weekends?
(For some thoughts on this see another opinion here:
http://amateurplanner.blogspot.com/2015 ... dules.html" onclick="window.open(this.href);return false; )
Instead, we get threats of shutdowns every few years. Perhaps I'm a bit pessimistic (those who know me are laughing right now...just a bit?), but my best case scenario is that a full scale shutdown would probably set us back 10-20 years on ever moving towards better commuter rail service. Transit authorities in this country have a terrible record with "we'll shut it down for a while, then bring it back better" kinds of commitments involving lower-ridership services.
I don't buy the arguments that there's so much work to do, that we should just give up on the whole operation on weekends. Yes, PTC and other work will cause impacts, but proper staging of work could shift the pain around the system, while keeping the non-impacted areas running.