The MIX Concept - Sustainable Transport

A Sustainable Transport for the Redesigned American Dream

by Shelia Sarkar and Boudewijn Bach

August, 1996


The convenience and comfort of automobiles in affording flexibility of travel patterns and movements coupled with an extensive network of roads (freeways, arterials and other secondary roads) for easier access have been shaping the lifestyles and land uses in the U.S. The freedom has come with a price -- environmental degradation; traffic congestion, urban sprawl, and most importantly, traffic crashes, which have been the leading cause of death in this country.

Remedial measures to control the environmental problems and urban sprawl have begun with the redesigning/designing of existing and new developments into more manageable ones. A case in point, is the transit-oriented development (TOD) proposed by Peter Calthorpe (an architect). As envisioned by Calthorpe, the residents and commuters in the compact TODs would be using vehicles sparingly and rely on green modes (walking and bicycling) for shorter distances, and on transit for longer commutes. Ideally speaking, this would resolve most of the existing traffic and environmental problems. Unfortunately, the real world is far from being ideal. Besides, the trip characteristics of individuals have been shaped by decades of automobile usage. Most Americans cherish their independence, privacy and the flexibility of travel, and existing transit systems are unable to meet such demands. Thus, an alternative sustainable transport that would have all the advantages of an automobile but would impact the environment least would be well-suited for the TODs.

This paper presents a concept of a sustainable transport that could be used both inside and outside a TOD and for long distance travel, with some adaptation. The name MIX was coined in the Netherlands to represent a combination or "mix" of the bicycle, PRT and the electric car. These vehicles would be light, compact, battery driven and have a range of up to 8 miles before recharging is needed. Additionally, the front wheel is connected to emergency pedals so the user can steer the vehicle to the nearest service station when the power runs out or there is engine trouble. The batteries can be recharged at service stations or by using solar cells on the roof of the vehicle. Figure 1 (70k) provides some detail on the characteristics of the MIX vehicle. For longer distance travel, the MIX vehicle would enter a Permanent Cable Rapid Transit (PCRT) network, queue up and be hooked to the cable and then move out of the station in a suspended manner. Speeds of up to 18 mph are envisioned on this cable system. The conceptual model is explained in great detail in the paper to assist those interested in taking it beyond this stage. This concpt will be presented at the TRB annual meeting in January, 1997, in Washington, D.C. It may be published in the Transportation Research Record or some other publication at some later date. Copies of the full paper can be obtained from the authors.

Contact information: Shelia Sarkar:; home page: -- Boudewijn Bach:

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Last modified: December 9, 1996