I noticed RTD had new buses last time I was there. I recall that the original TransTeq EcoMark buses were very progressive for their time. If I remember the story correctly, RTD couldn't find a company that built the right bus for them, so they went off and more or less built their own. Then, over the next decade and a half, I began to see their distinctive low floors and warty roofs in cities and airports all over the nation.
I proud of my little city for leading the way, but I'm a little sad to see that TransTeq seems to have disappeared. For a while, it seemed like their ideas were taking over the world. But at least the technology advanced overall.
Anyway, my favorite part about the new BYD buses on the Mall is their noise. They have a speaker on the front that 'growls' so that the otherwise-quiet buses have a harder time sneaking up on pedestrians. New solutions to new problems!