Signal Effectiveness Enhancement System

Abstract

The Signal Effectiveness Enhancement system utilizes audible warning apparatus to reduce the number of accidents due to rail-vehicle operators missing wayside signals. The system accomplishes this by monitoring the light patterns emanating from wayside signals to identify the displayed message such as: stop or limit speed and to detect faulty signal operation such as a dark signal. The system also tracks the speed of and the distance to approaching vehicles using a range measuring system located at the wayside signal or onboard the approaching vehicle. If the vehicle is complying with the displayed traffic control signal no action is taken. If the vehicle is approaching dangerously or if the signal is dark, the system triggers trackside sound generators located upstream from the wayside signal or triggers a warning system in the cab of the vehicle to gain the vehicle operator's attention.

Claims

1. Signaling Effectiveness Enhancer for use in conjunction with a vehicle for transporting at least one individual along a fixed guideway, wherein the improvement comprises: at least one first sensor disposed within the vicinity of or at a preselected location for sensing information with respect to a vehicle as said vehicle approaches said preselected location and providing at least one first signal indicative of said information; at least one first processor, said at least one first processor capable of analyzing said at least one first signal in order to provide at least one further second signal indicative of vehicle performance characteristics including at least a distance to said vehicle, a speed of said vehicle, and further information about said vehicle; at least one second sensor, said second sensor disposed within the vicinity of or at said preselected location senses a pattern of visible light emanating from a wayside signal disposed within the vicinity of or at said preselected location, in order to provide at least one third signal carrying at least one code indicative of said pattern of visible light; at least one second processor, said at least one second processor capable of an analysis of said at least one third signal using a predefined library containing at least one code indicative of a traffic control message and containing at least one code indicative of a wayside signal fault, a further fourth signal is provided for communicating at least one said traffic control message code, and a fifth signal is provided for communicating at least one said wayside signal fault code; at least one third processor, said at least one third processor capable of carrying out an analysis of all of said wayside signal fault code received via at least one said fifth signal, said vehicle performance information received via said at least one second signal, said traffic control message code received via said at least one fourth signal, wherefrom to compute a variable , if a magnitude of said is less than or equal to 0.9 for the case of a traffic control message being displayed calling for a stop at or near said preselected location, said vehicle is approaching safely and hence no change in said vehicle's performance is required. Wherefore if said magnitude of said exceeds 0.9 said third processor issues a sixth signal concerning at least one course of action in order to prevent an accident at or within the vicinity of said preselected location needs to be communicated to said at least one individual. a fourth processor able to receive at least one said sixth signal from a communication device from at least one third processor, said fourth processor controls at least one sound generator, said at least one sound generator generates a sound indicative of said course of action to at least the prevention of accidents at or within the vicinity of said preselected location, said sound generator is aimed at said vehicle's cab in order to communicate through transparent windows of said cab to said at least one individual and is activated by said sixth signal when said vehicle performance information indicates that said vehicle's cab is at or in the vicinity of at least one of said sound generators installed substantially upstream from said preselected location in close proximity to the fixed guideway.

2. The system as claimed in claim 1, wherein said fourth processor is located within said vehicle receives at least one sixth signal from a communication device using an electronic transmitter and an electronic receiver in order to control a sound generator located in the cab of said vehicle.

3. The system as claimed in claim 1, wherein said sound generators are omitted and the speed and range profile of each approaching vehicle along with the message displayed on the wayside signal is stored for later retrieval for analysis of each train operators performance or the performance of an automatic control system.

4. The system as claimed in claim 1, wherein a imaging light sensor located in the vicinity of the fixed guideway and upstream from a wayside signal, is imaging the wayside signal, in order to determine that said wayside signal is visible to individuals in the vehicle approaching the wayside signal.

5. The system as claimed in claim 1, whereby the range measurement is made by timing the two-way passage of a signal transmitted from the moving vehicle, received by a transponder mounted on the wayside signal, retransmitted to the approaching vehicle.

6. The system as claimed in claim 5, whereby a range measurement is made by timing the two-way passage of a signal transmitted from a moving vehicle approaching a second vehicle which is ahead of the moving vehicle, received by a transponder mounted on the rear of the vehicle traveling ahead and retransmitted to the following vehicle in order to determine if a rear-end collision could occur.

7. The system as claimed in claim 5, whereby a range measurement is made by timing the two-way passage of a signal transmitted from a moving vehicle approaching a second vehicle which is ahead of the moving vehicle, received by a retroreflective device whereby said retroreflective device encodes a retransmitted pulse with an identification code unique to each equipped vehicle to permit determining the range to multiple vehicles ahead.

8. The system as claimed in claim 1, whereby a stop-at-half-the-distance-to-the wayside signal is being displayed by the wayside signal, a 10% buffer is provided for this case of the magnitude of =0.45.

9. The system as claimed in claim 1, whereby a range sensor to be used in conjunction with said range sensor located on the wayside signal, is scanning perpendicular to multiple fixed guideways, said range sensor is located in advance of the wayside signal to determine which of the multiple tracks is occupied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 pictorially represents a light rail vehicle approaching a wayside signal which displays visual traffic-control messages to approaching vehicles. Mounted on the wayside signal is a range measuring device, such as radar. Upstream from the wayside signal the vehicle is passing a sound generator which is transmitting intense sound warnings toward the front of the vehicle's cab to warn the driver that he is approaching unsafely.

[0005] FIG. 2 represents a block diagram of the system that includes a visible light sensor and light pattern processor for detecting the pattern of light emitted by the wayside signal and transmits the traffic control message corresponding to the displayed pattern to the decision and control processor. Also included is a vehicle sensor and a signal analysis processor which computes the approaching vehicle's speed and range and transmits them to the decision and control processor which is able to detect a dangerous approach and activates the upstream sound generator to warn the operator of the approaching vehicle in advance of the hazard marked by the wayside signal.

[0006] FIG. 3 depicts an image capture device which records the full face of the wayside signal.

[0007] FIG. 4 depicts three photoelectric sensors each of which measures the light emitted by a single light emitting element of the wayside signal.

[0008] FIG. 5 depicts an image capture device located in advance of the wayside signal which captures the image of the wayside signal and detects loss of visibility of the signal due to atmospheric conditions, a low sun shining in the direction of the vehicle, the growth of foliage, or other inadvertent light blockers.

[0009] FIG. 6 depicts a mechanical semaphore outfitted with a gravity sensor to detect the position of the semaphore in order to determine the traffic control message being displayed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Signaling Effectiveness Enhancer for use in conjunction with a vehicle for transporting at least one individual along a fixed guideway, wherein the improvement comprises: at least one first sensor 1 disposed within the vicinity of or at a preselected location for sensing information with respect to a vehicle as the vehicle approaches the preselected location and providing at least one first signal indicative of the information, at least one first processor, the at least one first processor capable of analyzing the at least one first signal in order to provide at least one further second signal indicative of vehicle performance characteristics including at least a distance to the vehicle, a speed of the vehicle, and further information about the vehicle. at least one second sensor 2, the second sensor disposed within the vicinity of or at the preselected location senses a pattern of visible light emanating from a wayside signal disposed within the vicinity of or at the preselected location, in order to provide at least one third signal carrying at least one code indicative of the pattern of visible light;

[0011] at least one second processor, the at least one second processor capable of an analysis of the at least one third signal using a predefined library containing at least one code indicative of a traffic control message and containing at least one code indicative of a wayside signal fault, a further fourth signal is provided for communicating at least one the traffic control message code, and a fifth signal is provided for communicating at least one the wayside signal fault code; at least one third processor, the at least one third processor capable of carrying out an analysis of all of the wayside signal fault code received via at least one the fifth signal, the vehicle performance information received via the at least one second signal, the traffic control message code received via the at least one fourth signal, wherefrom to compute a variable if a magnitude of the is less than or equal to 0.9 the vehicle is coming safely to a stop with a 10% safety buffer in advance of the preselected location and no change in the vehicle's performance is required, in the case of a traffic control message requesting Wherefore if the magnitude of the exceeds 0.9 the third processor issues a sixth signal concerning at least one course of action in order to prevent an accident at or within the vicinity of the preselected location needs to be communicated to the at least one individual. a fourth processor able to receive at least one the sixth signal from a communication device from at least one third processor, the fourth processor controls at least one sound generator 3, the at least one sound generator generates a sound indicative of the course of action to at least the prevention of accidents at or within the vicinity of the preselected location, the sound generator is aimed at the vehicle's cab in order to communicate through transparent windows of the cab to the at least one individual and is activated by the sixth signal when the vehicle performance information indicates that the vehicle's cab is at or in the vicinity of at least one of the sound generators installed substantially upstream from the preselected location in close proximity to the fixed guideway.

[0012] To determine if a vehicle traveling on a fixed guideway is approaching a hazard marked by a wayside signal safely, the techniques disclosed below provide an algorithm for using the instantaneous velocity and range as measured by a range measuring device, such as radar or related ranging devices.

[0013] To determine if a vehicle traveling on a fixed guideway is safely approaching a hazard marked by a wayside signal, the techniques disclosed below provide an algorithm for using the instantaneous velocity and range as measured by a range measuring device, such as radar, to estimate how much of the distance remaining to the wayside signal will be required to bring the vehicle to the speed limit or to a complete stop for various conditions. The physics of a vehicle traveling longitudinally on a fixed guidewaysuch as on a railwaywhich is reducing its speed by applying brakes as it approaches a hazard marked by a wayside signal can be modeled with Newtonian mechanics. The basic equation of motion for the velocity is given by:

[00001]$\begin{array}{cc}V\left(t\right)=\left\{V_o-\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]*t\right\}.Math..Math.\mathrm{for}.Math.\text{:}.Math..Math.to& \mathrm{EQ}.Math..Math.\left(1\right)\end{array}$

[0014] Where: [0015] V(t) is the velocity at time, Tt. [0016] t is the time in seconds. [0017] V.sub.o is the velocity at t=0 (when braking starts). [0018] a is the acceleration (deceleration in this case) which is modeled as remaining constant over one braking event. (The magnitude of a, |a|, is then the average deceleration over the braking event.) The |a| applicable at a particular braking event is a function of several factors: [0019] Braking options available to the vehicle operator include: [0020] brake at a rate comfortable for standing passengers [0021] brake at a hard braking rate related to vehicle's braking system's characteristics [0022] activate the emergency braking apparatus [0023] Track conditions at a particular instant such as: [0024] water, ice, or show on the tracks [0025] sand or other particles blown onto the tracks. [0026] foliage falling onto the tracks [0027] A grade (an up or down slope of the tracks in railroad parlance) whose effect on the acceleration can be computed via the factor which computes the component of gravity acting in the longitudinal direction:

[00002]$\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]$ [0028] where: [0029] g is the acceleration due to gravity. [0030] h is the increase, or decrease, in height over a distance l. [0031] The ratio,

[00003]$\left(\frac{.Math..Math.h}{.Math..Math.l}\right),$

is the slope or the grade in the track in the railroad art.

[0032] Equation (1) can be applied to a braking event which starts at t=0 when the vehicle is traveling with velocity, V.sub.o, and ends when the velocity has slowed to V.sub.1 at t=T.sub.braking. Inserting these values for the variables in Equation (1) yields Equation (2):

[00004]$\begin{array}{cc}V\left(T_{\mathrm{braking}}\right)=V_1=\left\{V_o-\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]*T_{\mathrm{braking}}\right\}& \mathrm{EQ}.Math..Math.\left(2\right)\end{array}$

[0033] Where: [0034] V.sub.1 is the vehicle's velocity at the end of the braking event at t=T.sub.braking [0035] T.sub.braking is the time between when the velocity is V .sub.0 and when the velocity is reduced to V.sub.1.

[0036] Rearranging Equation (2) yields the braking time as a function of the change in velocity, the constant deceleration from applying the brakes and the grade of the guideway:

[00005]$\begin{array}{cc}{T}_{\mathrm{braking}}=\frac{V_o-V_1}{\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]}& \mathrm{EQ}.Math..Math.\left(3\right)\end{array}$

[0037] Then the distance traveled during the braking period is computed from:

[00006]$\begin{array}{cc}{D}_{\mathrm{computed}}=V_o*{}_{\mathrm{react}}+{}_0^{T_{\mathrm{braking}}}.Math.\left\{v_o-\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)*t\right]\right\}.Math..Math.\mathrm{dt}& \mathrm{EQ}.Math..Math.\left(4\right)\end{array}$

[0038] Then substituting Equation (3) for the upper limit on the integration, T.sub.braking, and introducing the variable, , for the ratio of the stopping distance to the distance measured by the range sensor, D.sub.measured, one arrives at:

[00007]$.Math.\mathrm{EQ}.Math..Math.\left(5\right)$$=\frac{D_{\mathrm{computed}}}{D_{\mathrm{measured}}}=\frac{V_o*{}_{\mathrm{react}}+{}_0^{\frac{V_o-V_1}{\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]}}.Math.\left\{v_1-\left[a-g*\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)\right]*t\right\}.Math..Math.\mathrm{dt}}{D_{\mathrm{measured}}}$

Where:

[0039] D.sub.computed is the estimated distance traveled during the time interval, T.sub.braking [0040] D.sub.measured is the distance of the vehicle from the preselected location at t=0 the vehicle is moving with velocity, V.sub.0. [0041] is the ratio

[00008]$\frac{D_{\mathrm{computed}}}{D_{\mathrm{measured}}}.$ [0042] .sub.react is the time required for the vehicle operator to react after receiving a stimulus carrying a traffic control message.

[0043] The integration in Equation (5) can be carried out to yield a closed form expression for a constant value of acceleration yielding:

[00009]$.Math.\mathrm{EQ}.Math..Math.\left(6\right)$$=\frac{D_{\mathrm{computed}}}{D_{\mathrm{measured}}}=\frac{V_o*{}_{\mathrm{react}}+\{\left(a-g*{\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)}^{-1}*\left[\begin{array}{c}{V}_o^2-V_0.Math.V_1-\\ 0.5*{\left(V_o-V_1\right)}^2\end{array}\right]\right\}}{D_{\mathrm{measured}}}$

A typical range for is 0.450.9. The 0.4 value corresponds to the common wayside signal aspect corresponding to the traffic control message instructing a train operator to proceed to one-half of the visible distance to the wayside signal and then halt. Allowing for a safety buffer of 10% of the distance one requires a of 0.45. If the wayside signal aspect corresponding to the traffic control message of stop at the wayside signal is being displayed, allowing for a 10% buffer a of 0.9 is required. For both of these examples calling for the vehicle to come to a stop which implies V.sub.1=0 in EQ (6) which simplifies the computation to:

[00010]$\begin{array}{cc}=\frac{D_{\mathrm{computed}}}{D_{\mathrm{measured}}}=\frac{V_o*{}_{\mathrm{react}}+\{\left(a-g*{\sin \left({\tan }^{-1}.Math.\frac{.Math..Math.h}{.Math..Math.l}\right)}^{-1}*0.5*V_o^2\right\}}{D_{\mathrm{measured}}}& \mathrm{EQ}.Math..Math.\left(7\right)\end{array}$

[0044] In a typical implementation the range sensor provides the range, D.sub.m, the velocity, V.sub.o, and the instantaneous deceleration, a, of an approaching vehicle. These values along with site specific information on the grade and the value of called for by the displayed traffic control message.

[0045] Consider the example of a passenger rail vehicle approaching the location of a wayside signal which is displaying a stop-at-the-signal (red) traffic control message. The railway at this location is flat (zero grade), and there are no weather conditions that would call for a derated braking rate. The radar mounted on the wayside signal is tracking the vehicle and its present distance measures 150 m, its speed is 13.2 msec (30 mph) and it is decelerating at a rate of 0.9 m/sec.sup.2 (a rate of of generally comfortable for standing passengers). Since the vehicle is decelerating assume that the driver has seen the stop traffic control signal and set .sub.react=0. Then using EQ (5) the stopping distance is 100 meters which is well within the 150 meters distance from the wayside signal and thus this is a safe situation. Now consider a second case with the vehicle at 150 m and approaching at a rate of 18 msec (40 mph). For this case, the stopping distance is 177 mwell beyond the 150 m distance from the signal.