WO1999054855A1

WO1999054855A1 - Road traffic control light signal system

Info

Publication number: WO1999054855A1
Application number: PCT/HR1999/000006
Authority: WO
Inventors: Krunoslav FRANJKOVIC
Original assignee: Franjkovic Krunoslav
Priority date: 1998-04-17
Filing date: 1999-04-16
Publication date: 1999-10-28
Also published as: HRP980209A2

Abstract

The road traffic control light signal system with display is designed for urban traffic control within any existing traffic control system. After giving a free transit to pedestrians or motorcars, the system displays the remaining transit time. The system, invented for the green signal, consists of the input monostable unit, the binary segmented decoder, the second counter, the tens counter, the digit counter, the digit display, the tens display and the display selection code unit. The system is mechanically adaptable to the existing traffic light housings, with only the front panel to be replaced. It is also adaptable to any traffic light terminal supply voltage. On the actuated display a green pedestrian figure appears to exchange alternately with the green numbers indicating the transit time. The pedestrian-number exchange goes on to the end of the preset time of transit. Once the exchange is ended, the numbers take over, i.e., the countdown of the signal time showing the road users the time left for safe transit. After the green signal, the red and yellow signals light up. At the end of the green signal the first pedestrians appears and then, alternately, e.g. every second, the pedestrians follow suit in the red light direction. After the yellow pedestrian only the red signal remains lit up. The red pedestrian figure is made of red LEDs and the yellow pedestrian figure of yellow LEDs. The electronic unit for the yellow signal consists of the seconds counter, the yellow display decoder and the counter trip unit (taking over when the yellow cycle is ended).

Description

ROAD TRAFFIC CONTROL LIGHT SIGNAL SYSTEM Technical classification of the Invention:

According to the International Patent Classification (IPC) the Invention stands closest to the following classes: - G 08 G 1/00 - Road traffic control system

- G 08 G 1/095 - Traffic lights

- G 08 G 1/96 - Time-lag indicators, e.g. mdicating a change after a certain duration of green light

- G 08 G 7/00 - Audio-visual traffic lights Technical problem:

Road traffic control signalling devices perform working and safety functions. The working function copes with the tasks that the systems are designed for, whereas the safety function should eliminate any risks arising from wrong signalling caused by a defect in the system or the human error. Therefore, such systems must have a self-control feature forestalling possible risks. As there is no absolutely reliable system, however, reliability is detemύned on the basis of assumed expected number (rate) of defects and the required operational reliability.

One of the worst problems in the road traffic control signalling, one that results in car accidents, is the unclear, i.e., unmarked duration of the signal for free transit (green light). The problem is particularly manifest in the moment when the road users are already given a go-free signal (green light), unaware of how much time is left until the next change. State-of-the-art: The first traffic lights were installed in 1868 in London on the crossing of Bridge St. and New Palace Yard, consisting of movable arms which, when raised high signalled free transit and when lowered warned of danger. In darkness these signals were given with a red-green gas-lantern. After a few days of trial run the gas-lantern exploded and these traffic lights were removed.

SUBSTITUTE SHEET(RULE 26J 2

The traffic lights as we know them today were first installed in Detroit '

(9 October 1917), as recommended by W.Ph. Enoa. In Europe the first tricolour lights were installed in 1926 in UK. The traffic lights installed in 1929 in New Haven and Baltimore (USA) were controlled by the traffic participants themselves. Control was performed by means of microphones and the drivers were signalling their requests by hooting. During the economic crisis in the thirties no further progress was made and the traffic control was entrusted to the police..The modernization and expansion of traffic light systems began after World War II, following the rapid increase in the number of motorcars. Electronic traffic control computers were first introduced in 1959. Optimum utilization of urban road networks is made possible by electronically controlled traffic lights.

Time-set control as a type of signalling control is based on a preset sequence and duration of the signal. A signalling plan is made to suit a particular traffic situation. As the traffic situation is changing over the day, traffic is indirectly controlled by changing the signalling plan in dependance on the parts of the day.

The traffic control light signal system consists of light signal units, light signals, detectors and cable network. Each signalling plan is wholly determined by the duration of a cycle (single-expiry time of the signalling plan), the green light duration split, the whole-cycle split, and the intermediate time (between the end of the green signal and the beginning of the opposite traffic green light).

Light signals are optical emitters of red, green and yellow lights. The source of light is placed in the focus of a parabolic reflector. Used as sources of light are ordinary or halogen bulbs. For prevention of phantom-like sunlight reflection likely to disrupt colour perception, special shades are installed in the reflector.

Standard lens diameters are 300, 210 and 100 mm, selected according to the intended use of a signal and its position. Installed in the traffic light systems are various symbols (for pedestrians, arrows, etc.). 3

The modern road traffic control systems viewed in terms of their own merit have been brought to technical perfection. They are ■ all fitted with installed devices preventing the green lights from simultaneously appearing to the road users coming from intersecting directions. However, the announced change in the colour of the light is rather problematic and not designed in a way which would credibly warn the greatest possible number of road users (drivers and pedestrians alike) of the imrninent change in the right of way.

In the world there are different ways of marking the approaching end of GREEN light, including: GREEN light is blinking over the last three seconds, or YELLOW light joins in. After a short while green light is out and yellow light remains to warn of the irrLminent change.

No matter how the green-light (free transit) change is signalled, many drivers tend to pass through the crossing. The drivers see green light without knowing how long it was on, how much time is left for transit. For that reason quite a lot of them pick up speed and when the colour change occurs they usually proceed, although the green light is out. THE ESSENCE OF THE INVENTION

The Invention is designed to ensure transit safety to maximum degree, for both the vehicles and the pedestrians crossing the pavement, and to increase traffic flow at intersections while at the same time contributing to the safety of road users to maximum degree.

What the Invention amounts to is this: the present GREEN light is replaced by a DISPLAY with green LEDs. When activated, the transit signal displays a green pedestrian and, after a while, a green number indicating the seconds of the programmed duration of the green signal. The number is DECREASED every two seconds for the road users to clearly see how much time is left for crossing the intersection. For example, if two seconds are displayed, the driver quite close to the traffic lights can safely proceed, whereas the driver behind, seeing the announced imminent change, can easily stop his vehicle. 4

90 A traffic light system equipped with such a display would warn pedestrians not to start crossing the whole width of the road if only 4-5 seconds are left, which would be particularly helpful to elderly persons. Drawings: The attached drawings show the traffic control light signal system with display

95 Fig. 1 traffic lights showing green

Fig. 2 traffic lights showing red

Fig. 3 wiring diagram

Fig. 4 layout of electronic elements

Fig. 5 wiring diagram

100 The road traffic control light signal system is intended for cities in any traffic control mode. Unlike other traffic lights, this system is "more intelligent" in that it indicates the remaining time of free transit, thereby helping pedestrians and drivers decide whether or not to start crossing in a given moment.

105 The operation of the system, as shown in Fig. 3, can be installed in any existing traffic control system. It can be mechanically adapted to the existing traffic light housings by changing the front panels only. It is adaptable to any traffic light terminal supply voltage. The traffic control automation can be of any type, because the system operates independently of the central intersection no automation.

The road traffic control light signal system with display (Fig. 3) is activated from the automatic control unit. First switched on is the input monostable unit which ensures that over the first four seconds the green moving pedestrian display lights up (Fig. 1). The pedestrian display is off after four

1 15 seconds, followed by the initial number preset by means of a group of micro- switches according to the instructions. The seconds counter starts the countdown and every second the display changes on the "digit downcounter". The decoder of a binary into 7-segmented code controls the segments from the LEDs in dependance on the state of the counter display. During a change in the 5

120 "digit downcounter" display from zero to nine the "tens downcounter"display is changed by one digit. The decoder of a binary into 7-segmented code connected to the "tens downcounter" controls the display of tens consisting of the same segments as the display digit. Once the countdown reaches zero on both displays, the seconds counter is tripped. With the displayed zero, the traffic

125 lights waits for the end of green or the begi iing of the pedestrian red (Fig. 2). During the countdown and according to the preset code, the display selection code unit alternately actuates the display of the number of the remaining seconds and the green pedestrians. The alternating pedestrian and numerical displays exchange, e.g. every two seconds until the last six seconds of the green no cycle when the remaining seconds are displayed.

The use of the road traffic control light signal system with display (Fig. 3) can be extended with an addition shown in the wiring diagram (Fig. 5). Upon teraiination of the green light signal and when the pedestrian red takes over, a pause ensues pending the green light for the motorcars corning from the

135 opposite traffic direction. It is followed by the pedestrian yellow signal (Fig. 2) urging the pedestrians on their crossing.

The light signal system (Fig. 5 and 2) is actuated from the automatic control unit. Red and yellow signals for pedestrians are simultaneously switched on. The pedestrian yellow display consists of five identical segments

140 made of yellow LEDs spread between the pedestrian green and red signals. First actuated is the pedestrian closest to green, followed alternately, e.g. every second, by the pedestrians in the direction of red. After the fifth yellow pedestrian only the red pedestrian remains lit up. The yellow light signal electronics consists of the seconds counter, the yellow display decoder and the

145 counter trip unit (taking over when the yellow cycled is ended). How to apply the Invention

The green light of the present light signal systems would be replaced by a green display showing the countdown of the traffic signal (the present green light). All light signal units operate automatically and have a built-in clockwork 6

150 adjustable for seconds. In other words, conditions already exist for installation ' of such a display, which reduces the replacement costs.

The Invention, if introduced in practice, would increase the traffic safety of both motorcars and pedestrians at intersections without significantly increasing the production costs of traffic lights. 155 Besides, the proposed display consumes less electricity (70 - 80%) and has a significantly longer life than the bulbs switching on and off repeatedly.

SUBSTITUTE SHEETfRULE 26)

Claims

7CLAIMS

1. The road traffic control light signal system with display using the red light to signal STOP and the yellow light to warn of the mrminent signal change is characterized by its use of a display with green LEDs for signalling free transit and showing the time left until the next change

(countdown).

2. The light signal system, according to requirement 1. above, which gets started when fed from the automatic control unit, is characterized by the monostable unit being connected to the red signal display made of LED segments and to the seconds counter, whereas the seconds counter is connected to the digit downcounter which by means of the binary segmented decoder changes the digit display and also the tens display through the binaiy segmented decoder; the digit downcounter and the tens downcounter are connected to the display selection code unit which in the course of countdown, in dependance on the preset code, alternately actuates the display of the iemaining seconds and green pedestrians.

3. The light signal system, according to requirements 1. and 2. above, is characterized by the yellow pedestrian display consisting of identical yellow LED segments spread between the green and red pedestrian signals that are being alternately turned off and on.

4. The light signal system, according to requirement 3 above is characterized by the yellow five-segmented display being connected to the decoder which in turn is connected to the seconds counter and the counter trip unit.