The average garbage truck gets about three miles per gallon, mixing long-haul trips to and from dumps with short start-and-stop pickups, invariably with the diesel engine idling. Garbage is picked up on schedules, not necessarily when the cans are full -- which could be well before or well after the scheduled stop. Our whole system of material use and disuse is due for a revolution; in the meantime, we can look for piecemeal improvements.
On the garbage collection side of things, there has been a step in the right direction. Wired reports on the BigBelly, a four foot tall solar-power trash compacting system able to crush 300 gallons of garbage into under 30 gallons of space. What's more, it signals a home base when it's getting full, so that pickups happen when needed, not according to a poorly-predicted schedule. Garbage truck use can be dramatically reduced with the BigBelly; the article cites a claim that four times/day pickups at commercial sites can be reduced to once every four days.
Early tests haven't been outstanding, but that appears to be largely due to user unfamiliarity and sanitation company ambivalence (or even hostility). The device looks more like a delivery company pickup box than a trash can, and widespread use of the BigBelly would clearly lead to a reduction in the numbers of garbage company employees. The manufacturer, Seahorse Power, appears to be getting greater interest from overseas markets than the US.
On the garbage truck end of the system, the introduction of hybrid-electric or hydraulic-assist technologies could make a huge difference in performance. Some hydraulic assist systems allow a 5 ton vehicle to accelerate from a dead stop to over 25 mph without using the diesel engine, with a recovery mechanism recapturing much of that power via regenerative braking. Current applications of these systems to big trucks seem to be in the delivery industry; I couldn't find any references to their actual or planned use in garbage trucks, just some speculation.
There's no question that reduce/reuse/recycle and cradle-to-cradle production models are far more worldchanging in their results than an improvement in the mileage -- and reduction of the use -- of garbage trucks could be. BigBellies and hydraulic-assist garbage trucks are incremental shifts, not systemic change. But we shouldn't discount the value, both environmental and cultural, of incremental shifts -- they can be tangible stepping stones to success, simultaneously letting people feel like they've accomplished something useful while reframing perceptions of what is possible.
At first I thought, uncharitably, "Oh boy! A machine that turns 1500 kilos of trash into 1500 kilos of trash." But if this could be used to compact *separated* trash, it could make recycling that much more effective and economical. If steel cans, PET, cardboard, etc., can be turned into a more compact package for hauling, and save fuel in the process, that's not too shabby.