A great big connected peloton.  Hmm - hazardous connecting bikes together.  What you could have is a big moving wind drag (like sail), and all the bikes get in the dam behind it.  Move at constant speeds - 10mph. Then you co-ordinate the intersections intelligently.

The problem remains - trucks.  Then the intersections have to be really smart.

Hello TripHop,

No, think more wildly.  Thirty recumbents on a four steel wheel frame, but only 2 or 3 ft high, same width, fully enclosed like the Japanese bullet train, but no gaps.  Frontal resistance and trailing drag minimized. Dedicated rail path with no intersections.  

When I ride my bicycle, I try my best to synchronize with the streelights so I do not have to use my brakes--I HATE scrubbing off my own energy.  Those pedal commuters who have to cover a longer distance would welcome a 'chain gang' effort to reduce the required energy vs. covering this distance alone.

Bob Shaw in Phx,AZ  Are Humans Smarter than Yeast?

assembling and disassembly (start/stop) would be an issue if there was any kind of connection.  Magnetic, possibly.  It could be done.  As for the streetlight synchronization - not too hard for automanous vehicles linked to the road system.

My system would have these sails moving to and fro and people accelerate to them from the curb and break from them in a converse fashion.  Dynamic - riders join and leave.  Hills present a problem - and thats where your powered system would excel.