This was originally posted as a comment on the Minneapolis Transit blog about increasing limited bus service.
1. Cutting service on the Selby section of the line to every 26-28 minutes is probably not a good idea. The line is rather well-patronized along that section with the current 20 minute headways and reducing it beyond that would make it much less useful (I think it should have more frequent headways, every 15 minutes, anyway). There's a lot of land along Selby which is either vacant or parking, and better transit service might serve as a catalyst for redevelopment. A better economy would help, too, of course.
2. The 21D is a farce. Supposedly it was wrangled by Saint Thomas in order to have better transit, but it is usually empty until it clears the river. The worst part is, however, that the 20 minute headways on the 21D match the 20 minute headways on the 63 which ends at the same stop, but no one at MetroTransit has ever thought of interlining (I asked). How much sense would that make? Lots. Grand Avenue's line would no longer dead-end at Saint Thomas, providing access from Grand to the LRT (to Minneapolis and the airport) and Uptown.
Furthermore, of the buses that run west from Saint Paul more than twice an hour (the 3, 16, 21, 63, 74 and 54), the 63 is the only one without a western "anchor." The 3 and 16 run to the U and downtown Minneapolis, the 21 to Uptown and the 54 and 74 to the Light Rail. The 63 ends in a residential neighborhood in Saint Paul. Finally, going from Grand Avenue to Downtown Minneapolis requires two transfers (unless you go east to Saint Paul, not feasible from the western part of the route), which is time consuming and inconvenient. Interlining with the 21D would solve many problems with little or no additional service required (except, perhaps, when the 21D doesn't run at rush hour). Running the 63 in to Minneapolis seems almost intuitive. I guess that's why it hasn't been done.
3. The bus stops along the 21 line from Uptown to Hiawatha (and in most of the Twin Cities) are way too close together. Since there is often someone getting on at every block, the bus winds up pulling in and out of every stop. No wonder it is scheduled to complete this section of route in 25 minutes, at a speed of less than 10 mph. If bus stops were halved few people would notice the longer walk (still generally under 1/10 miles) and the buses would be speedier. Plus, what it its real utility when it doesn't run at rush hours?!
4. Finally, the jog to University is very helpful for people who want to transfer there, but very time-consuming for through-riders on the 21. Perhaps the midday 53 could, instead of using the Interstate from Snelling to downtown, use Selby, with stops every 1/2 mile at major cross streets (Hamline, Lexington, Victoria, Dale, Western).
When this was changed some time around 2004 (from the historic Selby-Lake route dating back to the streetcar era), it increased the utility for travel to University and a transfer to the 16, but decreased the utility for cross-town trips by adding to the already-long run time of the bus. Considering how many people transfer to and from the 21 at University, it seems like it would almost make sense to have one leg of the 21 run on Selby to University and Snelling, and then west on University to Minneapolis, and another to run on University from Saint Paul to Snelling, and then west on Marshall and Lake to Uptown. Better 53 service would, of course, help as well, and just cutting off that jog, with half a dozen lights and a mile of extra route, would cut service times.