Tomorrow's Transportation: New Systems 
for the Urban Future

The following document is an excerpt from a 100 page 
report to the U.S. Congress that was submitted in 1968 
by President Lyndon Johnson. It was undertaken by the 
Secretary of the Department of Housing and Urban 
Development (Robert Weaver) at the request of Congress. 
Its purpose was to explore areas of research and develop-
ment that might ease the problems of Americans who live 
in and commute to work in cities. Research and develop-
ment projects that offer promising prospects for transporta-
tion improvements in our cities are identified as is a longer 
term program of R&D activities, concentrated in areas of 
greatest promise and benefits.

The report contains four sections: Urbanization and Urban 
Transportation, The Federal Role and Responsibility, What 
Should Be Done and A Recommended Research and 
Development Program. The excerpt below comes from the 
third section and bears the subtitle New Systems for the 
Future. It is a copy of pages 58-77 from the report.
From a 2009 viewpoint, it is a remarkably prescient piece
of work. There are few ideas, issues and technologies that 
are current today that were not identified some 41 years
ago. A copy of the full report may be available in large 
university libraries, such as the U of California at Berkeley 
and Northwestern University.


The following seven major types of new systems of all the many
candidates investigated, were found to possess not only a high
expectation of technical and economic feasibility but also to
contribute significantly to the solution of major urban problems.


A major failing of public urban transportation today is its
inability to provide adequate and attractive collection and
distribution services in lower density areas of a metropolis. In
some parts of urban areas and in many small cities and towns,
the travel demand is too small to support any transit service at
all. It is simply economically infeasible to route and schedule
present transit vehicles efficiently when only a few people want
to go to and from the same places during a short period of time.
Rail systems are too expensive and are technologically unsuited
for low volumes of demand. Ordinary buses cannot maintain
sufficiently frequent service in outlying areas to attract any but
those who have no alternative. What is needed is a public
transit system which can respond dynamically to the needs of
these areas, that is, a system whose routes and schedules are
both flexible and ubiquitous.

tt2.jpg (28548 bytes)The Dial-a-Bus, which is a hybrid between an ordinary 
bus and a taxi, could be the basis for such flexibility. It 
would pick up passengers at their doors or at a nearby bus stop
shortly after they have telephoned for service. The computer would 
know the location of its vehicles, how many passengers were on 
them, and where they were heading. It would select the right vehicle
and dispatch it to the caller according to some optimal routing program 
which had been devised for the system. Thus, the system could 
readily link many origins to many destinations.

tt1.jpg (34228 bytes)
A Dial-a-Bus, with it's position established by automatic vehicle 
monitoring, can be routed by  computer and a communication link
 to collect passengers who have called for service.

The diffused pattern of trip origins and destinations which
this system would serve is most dominant in low density suburbs.
But it also exists in a different form in the most thickly populated 
urban areas.

tt3.jpg (40499 bytes)The cost of taxi rides can be driven down by sharing 
rides, and basically the Dial-a-Bus system is designed to 
accomplish this. Data from the new systems study suggest that, 
depending on demand, door-to-door transit can serve its 
passengers almost as fast as a private taxi but at one-quarter 
to one-half the price, indeed, at only slightly more than the fare 
for a conventional bus.
With its operational flexibility, the Dial-a-Bus system could
be programmed to give different levels of service for different
fares. At one extreme it might offer unscheduled single pas-
senger door-to-door service, like a taxi, or multi-passenger serv-
ice, like a jitney. At the other extreme it might operate like a
bus service, picking up passengers along specified routes which
could include several home pick-ups. The system might also be
programmed to rendezvous with an express or line-haul carrier,
and in serving as either a collector or distributor, provide the
opportunity to improve the complete transportation service.

The major point is that the Dial-a-Bus might do what no
other transit system now does: Handle door-to-door travel
demand at the time of the demand. This means that the system
would attract more off-peak business than does conventional
transit. And if it does attract enough passengers, the off-peak
revenue would help Dial-a-Bus avoid the same financial prob-
lems of conventional transit, which is used heavily only 3 or 4
hours per day. It could also help reduce dependence upon

Technically, there is little question that the system will work.
Any number of existing vehicles can comfortably carry 12 to
24 passengers. Some of the best are now offering service to 
airports. Present computers, radio communications, and telephone
links are fully adequate to the major needs of Dial-a-Bus.

Mathematical routing and the associated computer programming
present no real obstacles. What must be done is to put these
isolated elements together into a unified system. Dial-a-Bus
service could be made somewhat more efficient if the buses
were equipped with automatic monitors to report each vehicle's
location, to the dispatchers at frequent intervals. Although these
monitors do not now exist, there is no technological barrier to
developing them, as discussed above under the automatic ve-
hicle monitoring subsystem.

The cost for a given level of Dial-a-Bus service is a function
of many variables. These include the nature of the street system,
the cruising speed of the vehicle, the distribution of demand,
and the size of the area served. Perhaps the most uncertain of
these variables is demand density, the number of trips generated
per square mile per hour. Dial-a-Bus systems probably will be
most efficient at demand densities of 100 trips per square mile
per hour—a level that is barely practicable for conventional
bus service.

A limited demonstration of the Dial-a-Bus concept, using
existing equipment, could almost certainly be achieved within
3 years at a cost of less than $1 million. A definitive full-scale
demonstration of Dial-a-Bus service, using vehicles and control
equipment specifically designed for this purpose to test the full
range of possible benefits, probably could be completed within
7 years at a cost of less than $20 million.

Current example:


The demand for transportation in areas of medium to low
population density is at the present time predominantly served
by private automobiles. Public transit trunklines may traverse
these areas, but collector-distributor service is poor if it exists
at all. More than half the automobile travel in large cities occurs
in such areas in trips longer than 2.5 miles. Increasing travel
demands of this kind, unmet by public transportation services,
tend to encourage multiple-automobile ownership and use;
often these additional automobiles can be neither afforded nor
efficiently accommodated.

tt6.jpg (22040 bytes)

To provide accessibility and service to the profusion of origins
and destinations in these metropolitan areas, a system is needed
which can be designed to be more responsive to the requirements
varying population densities and land use patterns might generate.
One such concept is "personal rapid transit," sometimes called
areawide individual transit or network transit. It would consist of
small vehicles, each carrying about the same number of persons
as an automobile. These vehicles would travel over an exclusive
right-of-way or guideway network, either over standard routes,
or else automatically routed individually from origin to destination
at network stations.

Personal rapid transit would serve all but the lowest density
suburbs with a network like that shown below. No part of
the urban area would be more than 2 miles from one of the
PRT routes.

tt4.jpg (88515 bytes)

Personal rapid transit would provide travelers the important
advantages of minimum waiting time at the origin station,
and private, secure accommodations. At the heart of the con-
cept is the premise that personal transit would serve a metro-
polis, except perhaps for its lowest density outskirts, with a
network or grid of lines, each perhaps a mile or two apart.

Empty passenger vehicles or "capsules" would be available
at each station on the network. The riders would enter one,
select and register their destination, and then be transported
there automatically, with no stopping. The average speed would
be essentially equal to the vehicle speed. The station spacing
on a guideway network for the system would have no influence
on speed of travel. Passenger demand and station costs would
dictate proper station spacing.

Empty vehicles would be recirculated automatically to main-
tain an inventory at each station, and passengers could be
routed past stations without stopping until they reached their
destinations. Ideally, such a system would give travelers the
same privacy as a private automobile, although during peak
periods in cities with particularly heavy corridor movements a
traveler might have to share a vehicle with two or three other

Shown below is an illustration of an at grade PRT station
which has off-line platforms for picking up and discharging

tt5.jpg (92018 bytes)

The guideway network covering the metropolitan area is
the essential ingredient of the personal rapid transit system.
Without a network of guideways the system could hardly avoid
conventional heavy dependence on work trips and a radial
orientation to existing central business districts. Thus, it could
not provide adequate transportation alternatives in large met-
ropolitan areas with a wide dispersion of trip origins and
destinations. No matter how sophisticated the technology,
transit which operates without some sort of network service
pattern almost certainly will remain a marginal service in the
movement of urban populations.

Network systems of personal rapid transit would perform
economically with travel demand ranging from 1,000 to 10,000
persons an hour in a travel corridor—the medium to lower
density conditions in which mass transit systems today usually
perform inadequately. Yet these corridor travel demand levels
prevail in most metropolitan areas. The network system, more-
over, could have average speeds of 50 to 70 miles an hour,
a substantial improvement over average urban freeway speeds.

The roadbed or guideway for personal rapid transit might
consist of rails or surfaces for air bearings; the vehicles could
use steel or rubber wheels or air pads. Propulsion could be in
the vehicle or in the guideway itself. Each guideway would
be about 5 feet wide and could be a single-lane over sub-
stantial portions of its length. The narrower and lighter structures
should require less land. They also could be more attractive
than many urban freeways. All these options are open
to the design engineer; no particular solution has yet been
shown to be outstanding. An illustration of a depressed
route is shown below. Other options include elevated,
ground level and underground.

tt7.jpg (41604 bytes)

A personal rapid transit system having these performance
characteristics is an important element in a viable urban trans-
portation system for a number of reasons:

An exclusive right-of-way is essential if public transportation
is to be automated and if it is to escape the congestion of general
street traffic. Forced to compete with automobiles on crowded
streets, other forms of mass transportation are inherently at a
speed disadvantage.
Automation can make transit service more competitive with
the automobile, since it is the only safe and efficient way to
operate a system using numerous small vehicles.
Small, individualized vehicles avoid the chief delays of pres-
ent rapid transit: Stops at intermediate stations for other pass-
engers and waiting or dependence on a schedule at the origin
Additionally, use of small lightweight vehicles, with the quiet
suspension and propulsion mechanisms which can be developed,
and the less massive elevated and station structures such systems
would permit, would minimize the impact of the system on the

The new systems study found over 20 existing proposals for
various kinds of personalized transit, most of them little ad-
vanced beyond the original concept. The greatest amount of
development work is needed for automatic electronic controls.
Maintaining safe headways to permit stopping in case of an
emergency on the line ahead is a very substantial problem in a
system using small vehicles and yet still aiming at high traffic
volumes. Such operation requires vehicles to be run far closer
together than they can now, but the problems involved in real-
izing this potential require further research.

A network of exclusive right-of-way transit on any such scale
poses obvious problems other than technical ones. Clearly a
major investment would be required, though costs might be
reduced by running the guideways on elevated structures using
the medians or margins of existing rights-of-way. Tunneled
guideways and grade level or depressed guideways would be
less expensive than conventional systems requirements because
of the smaller vehicle size of personal rapid transit.

Personal rapid transit could probably operate at costs below
10 cents per mile if its capacity were 6,000 riders per hour and
if the demand were sufficient to generate 15,000 riders per day,
on the average, over each section of guideway. In sum, the
real issues concerning the feasibility of personal rapid transit
systems, as for all new systems, are not merely technological
ones, they include the questions of cost and safety as well. These
questions cannot be answered with absolute precision at this
time, but indications are that personal rapid transit will be many
times safer than the private automobile, and yet will cost no
more than modern mass transit systems proposed in areas of low
to medium volume travel demands.
As shown below, personal rapid transit stations in the suburbs
could be reached by Dial-a-Bus and by private or public 
automobile service (PAS).
tt8.jpg (72427 bytes)
A prototype of such a system could be developed, working
perhaps from an existing system such as the Transit Express-
way demonstrated in a Housing and Urban Development (HUD)
project in Pittsburgh. Such a prototype system might minimize 
control difficulties, for instance, by requiring passengers to 
transfer—a requirement that might not be too onerous in some 
metropolitan areas because networks requiring few transfers 
could be designed.
An illustration of an inner-city personal rapid stations is
shown below.
tt8a.jpg (41732 bytes)

The ultimate goal should be a system that does not require
this kind of temporizing. Yet control problems become even
more complex in the areas of merging one vehicle stream into
another and of routing numerous small vehicles automatically
over a network of guideways, with provisions for switching off
the line at stations, of maintaining adequate supplies of empty
cars at stations, and of distributing vehicles so that congestion
does not result on any line. The new systems study found that
these problems are surmountable, and that a prototype system
could be developed, tested, and evaluated in less than 10 years
at a cost of about $250 million.
Current examples: and

On the outer fringes of the personal rapid transit system just
described, the network of lines in the lower density areas, to 
remain economical, would probably be too far apart for con-
venient walking access, and unsuitable for short neighborhood
or local trips. The new systems study found the dualmode
vehicle system to offer a possible solution to these problems. 
In a dualmode system, the vehicle can convert easily from travel
on a street to travel on an automated network. It thus could
serve as a logical extension or elaboration of personal rapid
The dualmode vehicles could operate on the parts of the network 
of lines used by personal rapid transit. Vehicles would drive from
the streets onto the guideway at selected PRT stations. Shown
below is a small car entering the network through an inspection
point, a destination encoder and an automated fare collector.

tt9.jpg (68778 bytes)

Dualmode personal vehicle systems would give the same
service for persons who did not own or know how to drive an
automobile as would the personal rapid transit system. They
would use public vehicles on the automatic guideways, and
would walk or transfer to other systems for local trips. How-
ever, the guideways also would be accessible to privately owned
or leased vehicles which could be routed on and off ramps con-
necting with ordinary streets, and driven over the streets to the
driver's destination just as in the case of an automobile. At the
point of destination, the vehicles could be parked as they are
today or, if they were leased for the trip, they could be turned
in at local connection points for redistribution to other users.
This last method has the advantage of minimizing parking
problems in congested areas.

A dualmode system presents more technical development
problems than the personal transit system. However, it should
be possible to work on such problems simultaneously with the
development of personal transit, and to so design personal transit
systems for ultimate dual mode use. The earliest developmental
problems will be in the adaptation of propulsion, suspension,
and guidance systems for use on both automatic guideways and
regular streets. None of them seems insurmountable in the light
of present knowledge.

Propulsion on the guideway, as in the case of the personal
transit system, would almost certainly be electric, probably using
third rail power distribution in prototypes. In the final develop-
ment of the system, however, propulsion might be a version of
the linear motor discussed previously. Vehicles would thus need
an electric motor; off the guideway they would run on batteries
or use a separate engine to generate power for the electric motor.

Since these are the directions in which propulsion technology
for ordinary automobiles may evolve to achieve reductions in
air pollution, the propulsion problems of a dual mode personal
vehicle are likely to be solved well before its other problems.

The most difficult technical problems are those associated
with the development of a control system. Two different courses
are possible. One is to concentrate the burden of control in the
automated guideway (using equipment like linear synchronous
motors and wayside computers) ; the other is to concentrate it
in the capsules. The cost and complexity of the guideways would
be reduced if the controls were in the capsule, but the controls
could be damaged when the capsules were off the guideway and
being driven by individuals, and there could be additional
safety hazards.
The personal rapid transit system described earlier could
operate at less than 10 cents per passenger mile with 15,000
passengers per day; the dual mode system might cost as little
as 7 to 8 cents per passenger mile, depending on whether the
vehicles were privately or publicly owned. 

If research and development of personal rapid transit and
the dual mode system were undertaken in concert, the prin-
cipal costs for guideways, controls, and propulsion systems
could be shared. The development, test, and evaluation of street
vehicles which could also operate automatically on the guide-
ways could add $150 million to the previous $250 million esti-
mate. While one first-generation form of the dual mode system
could be demonstrated in less than 10 years at a cost of less
than $35 million, the full-scale development, test, and evalua-
tion of a compatible personal rapid transit and small dual mode
vehicle system would be a more uncertain venture and could
require a total of about 10 years and $400 million.
Current examples: and Bubbles and Beams video


Medium-sized industrial cities (200,000 to 400,000 popula-
tion) have characteristically had difficulty in supporting public
transit service. Population densities are relatively low, and trip
distances are short over essentially radial routes between the
urban core and outlying residential and industrial areas. Pro-
viding peak-hour home-to-work travel, including both that be-
tween suburban homes and the rapidly expanding job oppor-
tunities in the outlying industrial and commercial zones, poses
major transit service problems. Some form of public transit,
improved over standard bus service, but with lower initial costs
and greater flexibility than rapid rail transit, is desirable to meet
the needs of the intermediate-size industrial city.
tt20.jpg (41755 bytes)

The automated dualmode bus would operate on the public
streets as a conventional bus to pick up and discharge passen-
gers. On longer high speed runs it would operate as a fully
automatic vehicle on a private right-of-way. Thus, it offers
the possibility for a system of public transit which combines
the high speed capacity of a rail system operating on its private
right-of-way with the flexibility and adaptability of a city bus.
This flexibility would make it possible for the transit system to
serve areas where the cost of extensive fixed rights-of-way could
not be justified, and to minimize the number of transfers which
the passenger would have to make.
A dualmode bus, after completing an express run on the guideway,
would enter the turnout and pick up a driver who would dis-
engage the external power supply and continue the run to dis-
charge customers or collect others for the next express trip. An
illustration of a typical interchange facility is shown below.

tt10.jpg (60062 bytes)
In the automatic mode, the vehicle would be powered elec-
trically from an external source. While in the manual or street
mode, propulsion might be initially from a turbo-electric power
plant.  Eventually,  an  all-electric propulsion  system  could
achieve minimum levels of noise and air pollution.

Because of the relatively long headways between vehicles
the controls for intervehicle spacing, speed, switching, and stops
are not as complex as those required by the personal rapid
transit or small dual mode vehicle systems. Nevertheless, the
controls will constitute a major portion of the research and
development effort leading to a demonstration of the automated
dualmode bus system. Significant efforts will also be required
for the design and development of the guideway propulsion
system and mainline stops for passenger entry and exit while
the vehicles are operated automatically. The redistribution and
effective use of vehicles and drivers during off-peak and manual
operating periods will require careful analysis. Consideration
has been given to the possible use of some of these vehicles as a
Dial-a-Bus during off-peak hours.

The automated dual mode bus could be developed and its
feasibility demonstrated very likely within 5 years at a possible
cost of less than $15 million.
Current example:


The most rapid population and employment growth in Ameri-
can cities today is in the suburban areas. As a result, the
percentage of trips having an origin or destination in a con-
centrated central city area is shrinking, and the number of trips
between low density residential areas and decentralized indus-
trial and commercial areas is growing. To accommodate this
growth pattern and to provide other options of urban development,
modes of transportation which span entire metropolitan
areas with circumferential, as well as radial links, are essential.
A corollary to the dual mode personal vehicle systems which
would provide this type of service would use pallets to carry
(or ferry) automobiles, minibuses or freight automatically on
high-speed guideways.
A rail-based pallet or ferry system could make good use of
abandoned or seldom used rail line in the city. An illustration
of such a concept is shown below,
tt11.jpg (88419 bytes)

Pallets have several advantages. For one, the individual
would not have to buy or lease special vehicles. For another, a
single freeway or rail line could be converted to pallet opera-
tion; automobiles in the area could use the pallet for high-speed
line-haul, thus preserving the quality of automobile comfort
without the disadvantages of driving in traffic.
In the rail system, the traveler's private automobile, with the
driver and any passengers remaining inside, would be loaded
on a pallet and transported at high speed. The automobile
would not need special equipment and the pallet vehicle would
not need to be much more than a platform or flatcar able to
carry about 10 to 12 vehicles. The concept is not limited to rail
systems, but could be adapted for guideways with electrically
propelled carriers.

The system would provide high-flow capacities per lane,
as well as automatic operations over long route segments. Load-
ing and unloading might be automated, although the operations
would have to be restricted to terminals with transfer

A major disadvantage of the pallet concept is that it would
serve only vehicles of conventional size. (It could, of course,
be restricted to special small vehicles, but only by losing a prin-
cipal advantage of general availability.) Thus, the pallet sys-
tems would not, in the long run, have much effect on congestion
in downtown areas unless it were coupled with extensive con-
struction of peripheral parking facilities or automated garages.

While only a limited comparison of a pallet and dual mode
system was made, the new system study concluded that each
had certain advantages in particular applications. A Federal
program of research should examine both on the basis
that a rail pallet system could initiate dual mode operation when
a substantial portion of metropolitan guideways were converted.
The feasibility of one form of rail pallet system could be demon-
strated within 5 years at a cost of less than $25 million.
Current example:


tt12.jpg (48626 bytes)The diversification of travel in and around major metropolitan
areas requires fast intraurban transit links to move relatively 
high volumes of passengers between central cities and suburban 
growth centers. Increasingly, they will be needed for line-haul 
travel not oriented entirely to central cities: Cross traffic among 
new towns, between satellite centers and international or regional 
airports, and as feeder-distributor systems serving the major 
high-speed ground lines along major regional corridors.

New systems of fast line-haul links will be essential in the development 
of new or renewed satellite communities. Indeed, they may be the 
only means to provide the focal points for future metropolitan 
development patterns alternative to continued regional sprawl.

The new systems study investigated all the conceivably feasible new types 
of fast intraurban transit links. At their best, they can be quieter, smaller, 
and less demanding in guideway requirements than current high speed 
intercity systems. Moreover, they can take less land, and can minimize 
adverse impact on areas adjacent to rights-of-way. For long-term development, 
speeds in excess of 100 miles per hour are difficult to attain economically with 
steel wheel suspension on steel rails because, for acceptable levels of 
vibration, tracks must be precisely level and an exact alignment. Further, 
vehicle stability requires weight, which is expensive to move. Support, 
suspension and guidance for several types of fast intraurban systems 
may evolve from the air-cushion principle.

Fast intraurban transit links can provide rapid access throughout
a metropolitan area between a number of distant locations, as 
illustrated below.
tt17.jpg (59434 bytes)

If future intraurban link systems are to succeed where commuter
lines have failed, they must be automatically controlled, with
vehicles capable of operating either independently or coupled
into trains. Automated systems of single-car trains would not
require a large labor force to operate them, and could be easily 
adjusted to fluctuations in demand. Linear motors for propulsion, 
air-cushion support and suspension for the higher speed ranges, 
and automatic vehicle monitoring, ticketing, and ridership counting 
equipment, would all contribute to safe, reliable, flexible service.

A fast intraurban transit station in a satellite city might look like
the following illustration.

tt13.jpg (38276 bytes)

Guideway dimensions, turning radii, and support structure
requirements for intraurban systems are such that fast transit
links could be installed in the medians or along the edges
of existing freeways. Rail rights-of-way could also be converted
in many instances.

One version of an intermediate speed intraurban link would
carry 80 seated passengers per car, for a system capacity of
16,000 passengers per hour. Another could carry 20 passengers
per vehicle and would be able to move 6,000 passengers per
hour in conditions approaching the convenience, comfort, and
privacy of the automobile. Higher and lower capacities could
be attained through changes in train lengths and headways.

A main central city terminal for a fast intraurban transit link might
look like the following illustration.
tt14.jpg (75522 bytes)
Both versions of intermediate-speed systems require extensive
technological development and economic analysis. The 
development, test, and evaluation of the 20-passenger-
per-car fast intraurban transit link system probably could be
accomplished in less than 10 years at a cost of less than $50

The new systems study also considered other imaginative
concepts for point-to-point travel systems, such as the gravity-
vacuum tube design, many monorail system designs, and also
various kinds of short-haul aircraft, both fixed-wing (vertical
or short takeoff and landing) and rotary-wing (helicopter)
types. Each of these types of systems, in their present and pro-
jected states of development, has some major problems, how-
ever, compared to other systems examined. Until these prob-
lems are resolved, such systems appear to offer few salient
advantages and would have relatively limited application for
travel within urban areas.
Current example:


Multitudes of people assemble each day in the major activity
centers of a city; large airports, shopping centers, industrial
parks, and universities, for example. Central business districts
are, of course, major activity centers. Provision must be made
for an adequate circulation system to better accommodate the
movement of people and goods within these centers. Cur-
rently, much of the travel in these areas is by pedestrians on
sidewalks. In a few cities, trains provide service in subways or
on elevated railways. In most areas, this circulation is now
provided by autos, taxis, streetcars, buses, and jitneys operating
on city streets, frequently under highly congested conditions.

Pedestrian movement in central cities can be aided by moving
belts (as shown on the right and left) or by a network of cab
transit (shown as crossing the throughfare) below.
tt15.jpg (59366 bytes)

The new systems study has identified several circulation sys-
tems which offer the potential for moving large numbers of
people over short trips in a relatively small area and are capable
of doing so safely, comfortably, economically, and with a mini-
mum of waiting. Because modal separation is imperative under
the congested conditions of travel in activity centers, such sys-
tems must operate on some kind of exclusive guideway. Follow-
ing is a discussion of the principal types of systems:

Moving Belts: Horizontal conveyor belts have been in use for
a long time. They have many advantages—low cost, no wait-
ing, no operators. A major disadvantage is their slow speed.
The very old, the very young and the handicapped cannot
get safely on and off sidewalks which are moving faster than
about 120 feet per minute (1.76 m.p.h.). In order to permit
safe loading and unloading, constant-speed belts must move
at such slow speeds that they can be easily out-distanced by
the average pedestrian. Previous prototype systems approached
this problem by having people board faster belts from adjacent
slow ones. Continuous parallel track layouts, however, are ex-
tremely expensive, cumbersome to accommodate, and involve
significant safety hazards.

There are several other ways to approach the problem of ac-
celerating belt speed from 1.5 to 15 miles per hour that the new
systems study found worthy of further development and ex-
perimentation. These include belts whose length or width can
be varied during operation. Two ways of using variable length
or "stretching)''' to produce variable speeds are to use a series
of rigid plates which would overlap at slow speeds, or a "win-
dow shade" device that could produce varying speeds. This
second type would be divided into sections attached at either
end to a series of carts or boxes that would move along at
varying speeds. The spacing between the carts or boxes would
be controlled mechanically; if they were a foot apart at a board-
ing speed of 1.5 miles an hour, they would have to move 10
feet apart at 15 miles per hour. As they moved apart the belt
material would unwind from the "window shade" reel in the
carts and the passengers on the belts would be smoothly

Capsule Transit: The complexity of moving belt designs sug-
gests that a type of small vehicle system may be more feasible
for major activity center use in the long run, if sufficiently high
carrying capacities can be achieved. A large number of con-
cepts have been proposed and several are actually being mar-
keted or are in use. Some use small cars propelled by moving
belts and are accelerated and decelerated by variable speed
rollers. Others substitute variable-pitch screws for the rollers
or cables for the belts. All of these proposals have technical
problems of one kind or another, such as the inability to pro-
vide for an emergency—like the failure of one car—without
shutting down the entire system. The new systems study rec-
ommends that investigations of them be included in a Federal
research and development program.
tt16.jpg (18856 bytes)Network Cab Transit: While traditional transit forms 
are applicable to downtown circulation, on-street forms 
suffer and contribute to congestion, while new subway systems 
are both very expensive and highly disruptive during installation. 
To meet these difficulties, the study considered narrow light-weight, 
low-noise systems, which can be suspended above city streets or 
sidewalks with a minimum of intrusion.

Two systems were proposed which consist of small auto-
matically controlled capsules. The capsules carry one or two
persons (with room for parcels) and run at about 15 m.p.h. on
tracks high enough above the street level to keep from inter-
fering with existing traffic. To use the system a person enters a
capsule at one of the many sidings and pushes a start button.
The capsule is automatically accelerated and merged into the
mainline traffic. Deceleration to a stop is done automatically
when the capsule is turned into a siding.

Capsules travel along the main lines only a few feet apart;
allow capacities of about 8,000 vehicles per hour. For the speeds
and loads involved neither propulsion nor suspension is a critical
issue; direct-current electric motors driving steel or pneumatic
wheels will probably suffice.

Many aspects of the new network cab system are similar to
personal rapid transit. Principal differences are in the speeds,
size of vehicles or cabs, and in spacing of the network grids. 
The network cab system is intended to cover a much smaller 
area than personal rapid transit. This similarity affords the 
opportunity for closely integrated development efforts which 
tie a circulation system for major activity centers together with
fringe area transportation systems like personal rapid transit.

 The most complicated part of these systems is the merging
and spacing control. In the simplest type of system, operation
would be in a single loop and the merging would occur only
when cars left stations. Each vehicle being merged would pro-
ceed only if a slot were available; slots would not be deliberately
created upstream of a merge point. Spacing would be uncon-
trolled except for the minimum amount necessary for emergency
stops. Speed control would not be precise, but would be limited
to the nominal system speed. More sophisticated versions are
possible, verging on the personal rapid transit system described

If developed concurrently, the feasibility of one example of
these types of systems could be demonstrated during a 5-year
period at a cost of about $6 million per system for a total pro-
gram estimate of $18 million. In order to fully develop, test, and
evaluate a series of desirable systems which could be certified
safe for public demonstration, a program extending over 10
years is estimated to cost approximately $118 million.
Current examples: and

Beyond this point, the report concludes with a Recommended Research and Development Program and three Appendices. Fourty-one years later, we find that nearly all of the technologies that were identified as "promising" in the report have been developed (or are being developed) and some are currently operational. Several additional similar examples are are described at the Innovative Transportation Technologies website. Links to 100+ innovative systems is provided at:

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Last modified: September 02, 2009