ongoing post: list of my favorite unusual bus designs
TRANSBUS
Dr. Zavanak wrote what is probably the definitive overview of the TRANSBUS program. From 1969 to 1977 the UMTA tried to design a new standard transit bus that would make buses a more appealing and accessible mode of travel. GM, Rohr/Flxible and AM General were contracted to make prototypes, which were then tested in various conditions. The program had major management issues, and none of them ended up being produced in any large numbers, although GM and Flxible based their RTS and 870/metro "advanced design" buses on these prototypes. The advanced design buses, with high floors and slow wheelchair lifts, became the standard for decades thereafter. The Rohr/Flxible prototype is by far my favorite. I love its tiny wheels, and the wheelchair ramp was prescient of what today's low-floors would end up using.
LAZ-360
Learning about this bus was my Sputnik Moment. Soviet Ukrainian ingenuity beat america to the low-floor bus by several years! the first prototype in 1968 was front-wheel drive, and the improved version in 1970 had four axles and electric traction. although the truss-following angled windows are unique to these prototypes, LAZ still makes buses with similar floor plans!
Northrop Grumman ATTB
From 1992 to 1999, the Advanced Technology Transit Bus was a somewhat more competent successor to TRANSBUS. It was commissioned by the SCRTD with the goal of improving efficiency by reducing weight, as well as improving accessibility. Although it was only a prototype, the program was very well documented, with TRB and Metro Library maintaining a lot of documents related to it; and the expertise gained in making its composite structure would be the basis for my next favorite bus, which is still in service today...
NABI 45C/CompoBus
A common and delightful sight on the streets of LA, the "double bubble" composite structure of these buses allows them to be five feet longer than most other transit buses without requiring a tag axle like most 45-foot coaches do. The interiors are notably quite spacious! They've been a mainstay of the J line busway for years, and although BYD buses are slowly starting to replace them there, the 45c's continue to ply many local routes across the system.