That's right, even in March I'm already experiencing wave-offs, where a bus I hope to take from Seattle's bus tunnel already has two bikes in its bike rack and I get waved off to wait for the next available bus. I've already been waved off once from the International District Station, and nearly got waved off a second time there.
The actual wave-off occurred all the way back in February from a southbound King County Metro #150, which drove up with two bikes filling up its bike rack. The bus driver shrugged his shoulders and said the next bus would be along in 15 minutes, then closed the door and went on. Fortunately for me, a King County Metro #101 came along just one minute later and I'd done enough research beforehand to know that even though it took me down a different route and would require a 3-mile bike ride to my office rather than the 1-mile ride after getting off the #150, I could still do it. So this didn't cost me much, though it would have been a lot more difficult for someone who hadn't done their homework ahead of time.
The near-wave-off also occurred with a King County Metro #150 bus, which this time was preceded by a #101 bus, and so I would indeed have had to wait for 15 minutes for the next bus. Three buses came through the tunnel one after the other. The first was a #101 with no bikes on board. The third was a #150 with one bike on board. All three buses stopped in a line, with the first two opening their doors. I had my bike clearly visible to all three drivers close to the actual stop, where I'd been waiting for about five minutes. Another bicyclist came down the stairs and immediately moved toward the #150 bus, but the driver waved him forward to the actual stop. As the other bicyclist moved forward, the two lead buses moved out and the #150 bus came to the actual bus stop, where I mounted my bike into its rack and boarded, so the other bicyclist probably had to wait that 15 minutes instead of me.
I have been very fortunate in my bike-commuting in not getting waved off often, other than when I was attempting to board eastbound buses from the Montlake Freeway Station last year, when this started taking me 20-30 minutes of waiting even in March and April, and so I eventually quit trying to do so entirely, bicycling all the way around the north end of Lake Washington instead. Two (or three) bikes per bus really isn't enough, especially with wave-offs already occurring fairly frequently, with Seattle attempting to increase its number of bike trips by a factor of 3 over the next 9 years, and with even Central Link light rail unable to accommodate very many more bicycles per train (I understand from a presentation I attended last year promoting Sound Transit's failed East Link proposal that each light rail vehicle will be able to accommodate only 2 bicycles). One thing I like so much about Personal Rapid Transit (PRT) is that each vehicle can carry a bicycle, and system capacities are expected to be in the neighborhood of 30 vehicles per minute, meaning up to 30 bicyclists and their riders can be carried every minute (= 1800 bikes per hour) by each PRT line. Compare that to 3 bikes per bus every 6 minutes (= 30 bikes per hour, maximum), or even 2 bikes times a maximum of 4 LRT vehicles per train every 5 minutes minimum (= 96 bikes per hour at a theoretical maximum) for Central Link light rail, and PRT looks like a huge boon to enabling human-powered transportation, especially when you consider that PRT vehicle headways are expected to eventually drop to just a half-second, quadrupling the number of bicycles that could be accommodated from the two-second PRT headways mentioned above.