U.S. patent number 3,750,099 [Application Number 05/235,757] was granted by the patent office on 1973-07-31 for pacing system for conveyances.
Invention is credited to Robert E. Proctor.
United States Patent |
3,750,099 |
Proctor |
July 31, 1973 |
PACING SYSTEM FOR CONVEYANCES
Abstract
Systems for pacing the movement of conveyances are disclosed,
each system being comprised of a stationary strip of equally spaced
bars, the longitudinal axis of the bars being transverse to the
direction of traffic (either erect on one side or horizontal in the
path of the traffic, such as on an airport runway) and means for
intermittently illuminating them simultaneously at a selected
frequency, where the frequency is selected to produce a
stroboscopic effect on an observer moving parallel to the strip of
such bars, such that only at a predetermined velocity will the bars
appear to be motionless, i.e., appear to have a velocity of zero
relative to the moving observer.
Inventors: |
Proctor; Robert E. (Los
Angeles, CA) |
Family
ID: |
22886796 |
Appl.
No.: |
05/235,757 |
Filed: |
March 17, 1972 |
Current U.S.
Class: |
340/932; 385/901;
340/953; 244/114R; 385/115 |
Current CPC
Class: |
G08G
1/07 (20130101); G08G 5/065 (20130101); G08G
5/0026 (20130101); E01F 9/20 (20160201); G08G
5/06 (20130101); Y10S 385/901 (20130101) |
Current International
Class: |
E01F
9/00 (20060101); G08G 1/09 (20060101); G08G
5/00 (20060101); G08g 001/09 (); G08g 005/00 () |
Field of
Search: |
;240/1.2 ;244/114
;356/23 ;340/22,25,31R,35,36,41,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Popular Science, March 1932, page 26. .
Popular Mechanics, August 1956, page 128..
|
Primary Examiner: Claffy; Kathleen H.
Assistant Examiner: Myers; Randall P.
Claims
What is claimed is:
1. Apparatus for pacing the movement of conveyances in a given
direction comprised of
a strip of equally spaced and stationary bars disposed parallel to
said given direction, said bars being more visible to an observer
in said conveyance when illuminated than the background surrounding
said bars,
means for intermittently illuminating said bars simultaneously at a
predetermined frequency to produce a stroboscopic effect on an
observer moving in one of said conveyances such that when the
velocity of said conveyance is greater than said predetermined
velocity within a given range of higher velocities, it will appear
to the observer that said bars are moving toward the observer, when
the velocity of said conveyances is less than said predetermined
velocity within a given range of lower velocities, it will appear
to the observer that said bars are moving away from said conveyance
in the direction of motion of said conveyance, and when the
velocity of said conveyance is equal to said predetermined
velocity, it will appear to the observer that said bars are
stationary relative to said conveyance.
2. Apparatus as defined in claim 1, wherein said bars are speced
apart a distance B and said frequency is selected for said desired
velocity V to satisfy a relationship
(VB/f) = N
where N is an integer, except zero, or any member of a set of
fractions (1/2, 1/3, 1/4 ...)
3. Apparatus as defined in claim 2, wherein said frequency is
chosen sufficiently high to be within the requirements of the
persistence of vision.
4. Apparatus as defined in claim 3, wherein said means is comprised
of individual flashed light sources mounted in fixtures.
5. Apparatus as defined in claim 3, wherein said means is comprised
of a flashing light source carried by said conveyance.
6. Apparatus as defined in claim 3, wherein said means is comprised
of an opaque conduit having said bars formed as apertures in said
conduit, each aperature being covered by a translucent shield, and
floodlights for filling said conduit with flashes of light from
each end of said conduit.
7. Apparatus as defined in claim 6 wherein said conduit has a
planar back wall diverging slightly from a parallel position with a
planar front wall having said apertures.
Description
BACKGROUND OF THE INVENTION
This invention relates to a visual aid for pacing the movement of
conveyances, and more particularly to an optical system employing a
stroboscopic effect for pacing the movement of conveyances such as
automobiles, trucks, buses, aircraft and watercraft.
Traffic congestion is one of the biggest problems of any large
metropolitan area. Its relation to the problem of pollution, its
drain on our major sources of energy, petroleum, and its rank as a
major cause of fatalities and injuries accentuate the need for new
methods to expedite the movement of conveyances, particularly
private automobiles, which will continue to be the preferred means
of transportation for a majority of the people. It is predicted
that the total number of vehicles registered in the United States
will increase 62 percent in the next 10 years over what it was 10
years ago, and 75 percent more vehicle miles will be traveled.
Obviously, the traffic problems cannot be solved by constructing
more roads, for the costs are too great and there is a growing
resentment by the public to the condemnation of land and housing,
and to the sprawl of surface transportation.
On arterial streets, freeways and highways during peak periods of
traffic, the flow of traffic is seldom orderly; more often it is
erratic, sometimes chaotic. The "stop-go" kinesis is familiar to
almost everyone who drives a motor vehicle. The erratic movement of
traffic, with its cyclic acceleration and deceleration of the
internal combustion engine, not only forfeits time but also reduces
the efficiency of the engine. The prime mover becomes a producer of
an inordinate quantity of noxious fumes, especially during periods
of deceleration. An engine running at constant speed is not
feasible. Nor is it possible to eliminate all erratic traffic
movement and the stop-go syndrome; however, the pacing of vehicular
traffic is possible and promises a vast reduction in the frequency
of occurrence of both.
The curtailment of stop-and-go driving in a network of city streets
will require a system which organizes the vehicles into platoons
and so paces them through most major intersections, at speeds
predetermined for each direction of traffic, that the platoons move
without interruption through a majority of the intersections. The
cost of erratic traffic movement is not measurable in terms of
gasoline consumption and wear on the vehicle; however, there can be
little doubt that it is enormous. The relationship between erratic
movement and accidents is a statistical record. The effect of
erratic movement on the health of drivers is understood, even
though imperfectly. In view of all these and other factors, the
cost of installing a traffic pacing system can be readily
justified.
The ultimate capacity of freeways, expressways and arterial streets
is unknown because as the traffic increases so does the erratic
movement of traffic until the movement degenerates into the
"stop-go" kinesis. A maximum capacity can be achieved only by
pacing, unless our present systems are to be replaced in the
immediate future by the electronic highway, which removes control
and decision making from the driver. This method of transportation,
although technologically feasible, will be evolutionary, not
revolutionary. A pacing system can, however, be revolutionary, thus
affording almost immediate relief from the problems of traffic
congestion.
There is increasing emphasis on external means for imparting
certain types of information to the pilots of aircraft. Visual aids
such as touchdown zone lighting systems, threshold lights, approach
slope indicators, taxiways and runway lighting systems now
constitute a branch of illumination engineering. A visual aid which
serves both as guidance and warning on landing and takeoff speeds
would be beneficial, a precaution which could prevent an overrun on
landing or a premature takeoff. One application of this invention
is just such a visual aid, and because of its inherent flexibility
it can be regulated to the performance characteristics of any
aircraft and, above all, it can compensate for wind velocity.
Still other applications for a pacing system provided in accordance
with this invention will be apparent. Accordingly, it is an object
of this invention to provide a pacing system that is relatively
inexpensive yet readily adjustable for use in a variety of
different applications.
SUMMARY OF THE INVENTION
Briefly, the present invention is comprised of a stationary strip
of equally spaced bars transverse to the direction of traffic
(either erect on one side or horizontal in the path of the traffic,
such as on an airport runway), and means for intermittently
illuminating them simultaneously at a selected frequency, where the
frequency is selected to produce a stroboscopic effect on an
observer moving parallel to the strip of bars, referred to
hereinafter as the strobostrip, such that only at a predetermined
velocity will the bars appear to be motionless, i.e., appear to
have a velocity of zero relative to the moving observer. At a
velocity near but greater than the predetermined velocity, it will
appear to the observer that he is overtaking the bars, and at a
velocity near but less than the predetermined velocity, it will
appear to the observer that the bars are moving away from him.
The novel features that are considered characteristic of this
invention are set forth with particularity in the appended claims.
The invention will best be understood from the following
description when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates one application of the present invention to
control noninterferring flow of platooned vehicles through
intersections.
FIG. 2 illustrates another application of the present invention to
transmit speed information to an aircraft taking off or landing on
a runway.
FIG. 3 illustrates still another application of the present
invention to transmit speed information to vehicular traffic in a
tunnel.
FIG. 4 illustrates an isometric view of a light source for the
application of FIG. 3.
FIGS. 5 to 7 illustrate one embodiment of a strobostrip for the
present invention.
FIGS. 8 to 10 illustrate another embodiment of a strobostrip for
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates schematically the use of a strobostrip for
pacing automobiles on city streets through intersections. For
convenience, only one intersection is showing; it has a traffic
signal 10. Traffic signals at other intersections in all four
directions are synchronized with the traffic signal 10 to stop
traffic periodically and thereby form platoons of vehicles which
may move continuously without interfering with one another at the
intersections if the platoons are properly paced, except as noted
hereinafter.
The pacing system shown is comprised of a strobostrip 11 along at
least a portion of each street on each side and viewed to the right
of each driver. Each strobostrip is in turn comprised of a
multiplicity of fixed, evenly spaced bars, as will be described
more fully hereinafter. These bars of a given strobostrip are
illuminated by flashes at a frequency regulated by a controller 12.
The means for illumination is assumed to be a high intensity source
at each end of each strobostrip, as will be more fully described
with reference to FIG. 5, but other means may be employed.
Regulation of the light sources, illustrated by dashed lines, is
electronic in that it requires only electrical pulses to be
transmitted by the controller to the light sources. The controller
may then be simply an oscillator, preferably a voltage-controlled
oscillator so that its frequency may be readily altered from a
remote location to regulate the pacing speed of traffic. The
controller also includes a timing system for the traffic signal 10
that is synchronized with controllers at all other intersections
crossed by the two surface streets shown. The frequency of the
oscillator in the controller is, of course, coordinated with the
timing of the traffic signal.
All platoons approaching any one intersection can be paced to
provide continuous movement through that intersection. Not all
platoons can be paced through every controlled intersection in a
network of streets but, the majority of them can because each
strobostrip permits pacing at any reasonable speed, with possible
variations of as little as 2 miles per hour.
It is not essential that the strobostrips be installed as
continuous bands for block after block. Once a platoon has been
organized and paced it can travel hundreds of feet without
referring to the strobostrip by simply maintaining speed until
another strobostrip is encountered to reconfirm speed or to adjust
to a different desired speed.
In pacing traffic, the spacing of the bars, the frequency of the
flashes and the speed of a vehicle are related, one to another,
with the result that the bars present to the driver of the vehicle
a stroboscopic effect of motion or no motion, depending on the
speed of the vehicle. When the bars appear to be motionless, the
vehicle is proceeding at the selected control speed. At a speed
near but less than the control speed, the bars appear to be moving
away from the driver of the vehicle in the direction of travel,
whereas at a speed greater than the control speed the bars appear
to be moving toward the driver. Thus the stroboscopic effect is
used to continuously convey to the driver of each vehicle the
information needed to regulate the speed of the platoon to that
which has been determined to be the optimum for orderly movement of
all of the traffic.
As noted hereinbefore, conventional traffic signals, incorporated
into the pacing system, are timed to move the traffic
progressively. The number of vehicles comprising a platoon will
depend upon the duration of the "green" period of the traffic
signal cycle at a given intersection. The "red" period will hold at
the intersection those vehicles which have yet to become members of
a continuously moving platoon. The frequency at which any
strobostrip is flashed and the durations of the green and red
periods of a traffic signal are capable of being regulated over an
extensive range.
This pacing system does not require the use of a computer except
for merging traffic from on-ramps with freeway traffic. However,
computer control of the flashing rate in a specific speed range and
of the traffic signals for a complex traffic situation can be
accomplished with known computer programming techniques.
The stroboscopic relationship among velocity V, in terms of
feet-per-second, the bar spacing B, in terms of bars-per-foot
(horizontal) and flashing rate f, in terms of flashes-per-second,
is given by:
(VB/f) = N
in which N is any integer, except zero, or any member of a set of
fractions (1/2, 1/3, 1/4 . . .). This relationship will produce
synchronism between the strobostrip and the vehicle at a desired
velocity.
From this relationship, the values of B and f can be selected for
the desired velocity such that, at the desired velocity the bars of
the strobostrip will appear to be stationary relative to the driver
of the moving vehicle. This then is the pacing speed, a speed at
which traffic organized into platoons will travel with order on the
city streets.
The real motion of a vehicle will always be toward the bars of the
strobostrip, but the apparent motion of the bars will either be
toward or away from the vehicle depending upon whether the
vehicle's velocity is greater or less than V. This stroboscopic
motion of the bars can best be understood by assigning a value of 2
to N in the above equation. When the repetition rate (VB) of the
bars exceeds the flashing rate f, the strobic motion of the bars is
toward the vehicle, i.e. in a direction opposite to the motion of
the vehicle. At this repetition rate, the quantity VB/f is slightly
greater than 2. When the repetition rate of the bars is less than
the flashing rate, the strobic motion of the bars is away from the
vehicle in the same direction as the actual motion of the vehicle.
At this rate VB/f is slightly less than 2. Accordingly, if the
velocity of the vehicle is greater than V, it will appear to an
observer that he is overtaking the bars, and if less than V, it
will appear to the observer that he is following behind the bars
which have an apparent motion in the direction of the vehicle's
motion.
The stroboscopic motion assumes that the flashing rate f has been
chosen sufficiently high to be within the requirements of the
persistence of vision.
The persistence of vision is approximately one-tenth second.
Therefore, the flashing rate should be such that an observer on a
moving vehicle will see bars illuminated by the flashes at a rate
greater than 10 per second, such as 25 per second, at the desired
velocity V. The values for the spacing B and the frequency f for
the desired velocity V can be easily chosen. In practice the
spacing B is chosen with practical consideration of physical space,
and the frequency f is then selected. To increase, or decrease, the
chosen velocity V within a reasonable range, the frequency f is
simply increased, or decreased, proportionally to produce
synchronism at a higher or lower velocity.
Synchronism can occur at a higher and a lower velocity than that
desired, i.e., than that set by the frequency f selected for a
predetermined number of bars/foot. However, the difference between
the other velocities that will produce synchronism and the desired
velocity will be so large that the driver of a vehicle being paced
will not be confused or attempt to synchronize at those other
velocities.
The velocities at which synchronism can occur above and below the
desired velocity can be predetermined. There is then a given range
of higher and lower velocities within which the desired
stroboscopic effect will take place. Proper selection of bar
spacing will assure that the range will be sufficient to avoid
confusion for a given velocity. Although it will not be possible to
segretate all traffic into noninterfering platoons at each major
intersection, as noted hereinbefore, the majority of vehicles can
be so ordered. The elimination of such a large volume of stop-go
traffic will yield immeasurable benefits in the reduction of
exhaust emissions, increased mileage per gallon of gasoline and
increased engine life (or decreased repairs).
Another use of this invention is, as referred to hereinbefore, to
merge the traffic on the on-ramp of a freeway smoothly into the
flow of traffic on the freeway. The installation would be comprised
of strobostrips mounted on the right side of the freeway and the
on-ramp to be controlled, a conventional traffic signal to control
traffic onto the on-ramp and a computer programmed to control the
traffic signal and the flashing frequency f of the strobostrip to
pace vehicles onto the freeway into gaps in the freeway traffic
sensed by vehicle detectors on the freeway. By cyclically pacing
the freeway traffic at high and low velocities, the necessary gaps
in the freeway traffic are created. To pace vehicles on the
on-ramp, vehicle detectors could track the progress of a platoon of
vehicles and feed data into the computer to program acceleration of
the platoon into the moving gap in the freeway traffic.
This invention may also be employed to communicate speed
information and to regulate speed under a variety of conditions,
and for types of vehicles other than automobiles, trucks and buses,
such as: trains in and near congested communities, as well as in
approaches to terminals; and aircraft on takeoff and landing. In
the case of aircraft, the strobostrip may be placed adjacent to the
centerline of an airport runway, as shown in FIG. 2 for a
strobostrip 20 in a perspective view of an airport runway 21 which
might be viewed by a pilot on an approach to a landing. The
strobostrip thus serves as a guide as well as an indicator of
optimum landing speed.
Similar landing strip lighting has been successfully employed in
airports. It is therefore feasible to provide such lighting in the
form of a strobostrip with the flashing rate controlled for the
desired ground speed of an approaching aircraft taking into
consideration the type of aircraft and the wind velocity at the
time. In this, as in other types of applications of the invention,
the bars of the strobostrip may be illuminated by a source carried
by the vehicle, as shown in FIG. 2, such as a Xenon lamp repeatedly
triggered at the desired rate or frequency.
For those applications using a flashing light source carried by the
vehicle, the strobostrip bars may be comprised of microscopic
prism-like particles or glass spheres embedded in a thermoplastic
sheet, or simply a plastic tape made brilliant by a suitable
pigment. In some applications, it may be advantageous to shade the
bars for good day and night visibility. Where the requisite high
visibility is unobtainable during the hours of daylight, it may be
necessary to limit the use of the strobostrip to only those hours
between dusk and dawn. However, those are usually the most critical
hours so that installation costs of such a vehicle-illuminated
stroboscopic strip can still be justified, particularly if, in the
daylight hours, the strip serves another useful purpose, such as a
guideline on the runway of an airport.
FIG. 3 illustrates the application of the present invention to the
task of pacing traffic through a long tunnel, using a plurality of
light fixtures, such as a fixture 26 illustrated in FIG. 4. The
fixture houses suitable lamps, such as fluorescent or Xenon lamp.
It is preferably made of opaque material, such as sheet metal with
a translucent panel 27. The panel may be colored with a suitable
pigment, or may be simply white as in standard fluorescent light
fixtures. The slope of the panel, relative to the direction of
traffic flow, is selected to minimize visibility of the panel by
traffic moving in the opposite direction in order that traffic in
opposite directions can be paced at different speeds without
confusing the drivers on one side by the stroboscopic effect of the
flashing light on the opposite side of the tunnel. For a wide
tunnel, or for controlling traffic in both directions at the same
speed, a single lamp, housed in a diffuser would be adequate.
The foregoing illustrates the great utility and versatility of the
present invention, and demonstrates that many techniques are
feasible for implementing a strobostrip. All that is needed is a
strip (rectilinear or curvilinear) of properly spaced bars, and
means for illuminating them with light flashing at a frequency
calculated from the general equation set forth hereinbefore. The
illuminating means may be, for example, as shown in FIGS. 5 to 10,
a flashing light source carried by the vehicle, as suggested
hereinbefore with reference to FIG. 2, or individual flashed light
sources mounted in suitable fixtures as shown in FIG. 4. Other
techniques for implementing a strobostrip will suggest themselves
with front lighting, edge lighting or back lighting, using in each
case any suitable light source. A strobostrip may even be formed as
a panel of light-emitting diodes. It is, therefore, intended that
the claims be interpreted to cover all forms of strobostrips, and
not simply those expressly suggested, or those of some particular
interest to be described with reference to FIGS. 5 to 10. In FIG.
5, a top view of a strobostrip partially broken away is shown
comprised of an opaque conduit 30 having aperatures 31 covered by a
translucent shield 32 to form a vertical bar as more clearly shown
in FIG. 6. The shields may be smooth on the outside for ease in
cleaning, and finished with prism-like facets on the inside for
greater diffusion of light passing through aperatures in the
conduit. Other alternatives for the shield include lining the
inside with optical glass spheres, or applying to it a suitable
brilliant pigment.
Light flashes are introduced into the conduit from each end by
floodlight units 34 and 35. Each unit includes two stacked
floodlights, as shown in FIG. 6 for the unit 35, to provide a beam
having a vertical dimension substantially equal to the height of
the vertical bars. The inside of the conduit walls are reflective
surfaces. Beams of light are repeatedly reflected from the walls to
virtually fill the entire conduit with light beams that illuminate
the front apertured wall everywhere, including the aperatures, thus
forming spaced bars of light each time the floodlight units are
flashed simultaneously.
A floodlight unit at each end of the conduit assures more uniform
light intensity for the bars. At each aperture, some light escapes
from the conduit, thereby diminishing the intensity of the light
from one unit as the flashed light beams travel to the other end of
the conduit; however, with light beams traveling from the
floodlight unit at the other end, lumens at each aperture will be
approximately the same. To ensure that there will be no "dead
areas" in the conduit, the plane of the back wall may diverge
slightly from a parallel position with the plane of the front wall,
as shown in FIG. 5. The effect would be to progressively diverge
the light from one end and converge the light from the other
end.
FIG. 8 shows schematically a plan view of another strobostrip
embodiment using fiber optics to distribute light flashes from a
source to bars 40. Each of the bars, represented by circles, is
positioned directly opposite an aperture 41 in a conduit 44 which
encloses a bundle of parallel hollow tubes 42. One end of each tube
42 is connected to a different bar 40 by a bundle 43 of optical
fibers as shown in FIG. 9. The bar is a hollow cylinder or square
tube having a translucent viewing side 41A and a back 42B lined
with high intensity reflective material of prismatic facets,
microscopic optical glass spheres or brilliant pigment, any one of
which is represented in FIG. 9 by the rough inside surface of the
back 42B.
The other end of each tube is connected to a light distributor 45
comprised of two simultaneously flashed and opposing light sources
46 and 47 and a revolving mirror 48. As the mirror completes one
revolution, light will be distributed to the tubes 42 twice, once
from the source 46 and once from the source 47.
The distributor includes on each side of the opposing light
sources, a plurality of short radial tube sections 49, one section
for each tube 42. The sections are held in place by a hoop 50
having apertures 51 and 52 for the beams from the sources 46 and
47. The ideal sources will be continuous wave (CW) lasers with
their pencil-thin beams. Other light sources would require
appropriate reflectors and lenses to produce a beam which is very
narrow in one plane. The illumination of more than one radial tube
section at a time will not affect the performance of the
distributor. In this instance, the more narrow the beam, the
greater its intensity. Whatever their sources, these beams will
have their center lines lying in the same plane as the center lines
of all of the radial tube sections 49. Each radial tube section 49
is then connected to a parallel tube 42 by a bundle of optical
fibers 53. In that manner, the revolving mirror distribures the
light beams and controls the frequency of the flashes at the
bars.
For each application, and each strobostrip arrangement, the control
system for flashing the light source, or sources, may include a
voltage controlled oscillator and a programmed digital computer to
compute the correct control voltage for the oscillator to flash the
bars of the strobostrip at the right frequency f for a desired
velocity V. The output of the computer could be converted to an
analog signal through a basic digital-to-analog converter. Manual
control or override can be provided at the digital-to-analog
converter. Although particular embodiments of the invention have
been described and illustrated herein; it is recognized that
modifications and variations may readily occur to those skilled in
the art. It is therefore intended that the claims be interpreted to
cover such modifications and variations.
* * * * *