Automobile Turn Indicators

Abstract

Automobile turn indicators currently in use have limitations in communicating the actual intended maneuver a vehicle is likely to perform. For example, a vehicle intending to perform a U-Turn maneuver uses the same indicator as that used for either a right or a left turn depending on whether a LHT (Left Hand Traffic) or a RHT (Right Hand Traffic) regime is in operation in the region in which it is moving. The same indicator is also used for indicating changing of lanes or permitting a passing (overtaking) maneuver to a following vehicle on request. Some thoughts are presented in this article to overcome these and other limitations by using coloured LEDs to display the intended maneuver. 

Click Here for PDF Version – Automobile Turn Indicators

Introduction

Set of turn (left/right) indicator lights (flashers) are provided in the front, sides and rear end of all motorized vehicles as appropriate considering the vehicle class and type. In some models these are also provided on the external rear view mirrors. The turn indicator lights on a vehicle guide the pedestrians and other vehicles (both, motorized and non-motorized) moving in the vicinity to make appropriate maneuvers (proceed, slow down or stop). The flashers are yellow or amber in colour in general. In some countries, however, the front flashers could be white in colour.

The flashers located on the right hand side of the vehicle communicate to other road users the maneuvers, such as, changing lanes rightwards or turning right or turning-U to right, which the flashing vehicle intends to perform. Likewise, the left flashers indicate to the corresponding manoeuvres in the opposite direction. The flashers are controlled by a lever or a stalk. The clockwise movement of the lever turns on right flashers and anti-clockwise movement turns left flashers. The movement of the lever, in general, corresponds to the movement of the steering and the resultant turn.

The other lights external to the vehicle which guide the other road users are the red coloured tail lamp and break light and fog lights and others. The whole set of external lights and indicators could be termed VMIS (Vehicle Maneuver Information System) with a subsystem termed VTIS (Vehicle Turn Indicator System) comprising of the turn indicators or flashers. VMIS is in use for many years and served fairly well thus far. However it has limitations.

VTIS Limitation

The current system of turn indicator lights has a limitation if a vehicle intends to turn “U” from the right/u-turning lane at traffic signals or, from a parked state (parallel to the road), either from the left or right side of an undivided carriageway.  Currently, hand signal by the driver or co-passenger indicates the U-Turn. Not possible when window glass is drawn up in AC vehicles or raining. Further the flashers communicate different confusing messages, such as, changing of lanes, permitting an overtaking maneuver and turning. All in one colour which, needs to be deciphered according to the position of the vehicle on the road. The discussion is mainly limited to Indian conditions where traffic moves to the left side of the road termed “Left Hand Traffic” (LHT) using RHD (Right Hand Drive) vehicles. But VTIS modifications suggested later would be applicable globally with appropriate changes, if any, as are needed to the specific country using LHD (Left Hand Drive) vehicles and RHT (Right Hand Traffic) regulation which necessitates traffic movement to the right side of the road. The following explains the some of the limitations of the current turn indicators.

(A) - U-Turning at Traffic Signals – vehicles intending to turn “right” or “U” move in the same lane of a carriageway. The speeds of vehicles are governed by the stages - initial, middle or tail end - of the green phase of a signal permitting this movement. Normally, users of every following vehicle assume that the leading vehicle turns right as shown in green. But some realize, a little later, that the leading vehicle is turning “U” (as shown in red) and either slow down or stop depending on the spacing available between the right hand side rear end of the leading vehicle and the right hand side front end of the following vehicle. Or swerve a little to the left as shown in yellow, to avoid collision with the leading vehicle, but endangering itself and vehicles moving straight ahead in the adjacent straight lane or vehicles turning right from the second right turning lane. This also depends on the phasing of the traffic signals adopted to control the flow at a specified intersection. 

(B) – U-Turning at Un-Signalized Intersection - At unSignalized intersection movement of vehicles entering the intersection from other approach arms may be endangered in the absence of appropriate information as the paths of the U-Turning vehicle (UTV) and other vehicles intersect. For example, the path of the vehicles approaching from right (orange) and that of the UTV (red) intersect as shown here. The impact of U-Turning information gap here could be greater as the speeds of vehicles are more uncontrolled here than at signalized intersections.

(C) - U-Turning from Left Side of a Road (Undivided Carriageway) – A Vehicle user intending to turn “U” switches on the turn indicator light on the right hand side of the vehicle. However, the users of other vehicles in the vicinity, either coming from behind of the UTV or from the front, initially understand that it is going to merge in, as shown in green, in to the flow of traffic coming from behind and move straight on but from the position and angle it is forming to the road, realize that it would be turning “U” and stop or slow down or proceed making risky maneuvers – as shown in yellow among many possible maneuvers - while creating a chaos on the road. The reason for the chaos on the road is mainly due to the UTV and compounded by the discipline or otherwise of other road users. Elimination of information gap between UTV and other vehicles could result in safer maneuvers as shown on the right hand side figure.

(D) - U-Turning from Right Side of a Road – Some vehicle users, especially in unregulated places, park vehicles on the RHS of a road. Vehicle user intending to turn “U” switches on the turn indicator light on the left hand side of the vehicle. The users of other vehicles in the vicinity as described in the earlier Point (C) initially understand that the vehicle is going to cut across the oncoming vehicles and merge into the traffic coming from behind but realize later that it is going to turn “U”. In this case also the reaction of users of other vehicles would be similar to the ones at Point (C).

The above situations may end up in undesirable events and the same may be eliminated or reduced to the extent possible perhaps by providing appropriate U-Turning indicators on the front & rear ends; and, on the sides of a vehicle.

This requires a change in the design of turn indicator lights to flash either a left or right arrow on the corresponding side of the vehicle to indicate the normal left/right turn and an appropriate U-Arrow (U shaped arrow) to indicate the corresponding U-Turn.

Suggestion - U-Turn Indicator (U-TI)

•       A button switch in the turn indicator lever to control the operation of the UTI.
•     Pressing of this button switch during/after shifting of the turn indicator lever to the desired  turn position activates the corresponding U-Turn.
•      The design of this facility should be such that on completion of the desired U-Turn not only  the turn indicator lever returns to the neutral position but the button switch also returns to  normal position. 
•      A double press option may be provided on the button switch to deactivate the U-Turn in  case of accidental pressing of the button.
•    To prevent even accidental pressing of the button switch, the head may have slight depression or a concave shape and the switch placed inside it.
•      It should be possible to generate patterns that indicate left turn and left U turn or right turn and right U turn using LEDs.

Benefits

·         Reduces the information gap between UTV and other vehicles on the road

·         Reduces the information gap between UTV and pedestrians on the road

·         Eliminates hand signal confusion due to non standard hand movement

·         Dangers associated with single hand U-Turning of a vehicle would be eliminated

·         AC vehicles need not draw down windows for hand signal

·        Facilitates provision of appropriate information on a rainy day (when even hand signal is not possible)

Additional Features to VTIS – The use of LEDs and different positions of the lever controlling the turn indicators could facilitate in providing additional features. The lever can have three positions (up, centre and down) in the vertical plane and each of these vertical plane positions can have three horizontal plane positions (forward, centre and backward). The centre position in the vertical plane and the corresponding horizontal plane positions (forward and backward) are being used for controlling the lights. Each of the remaining positions (some of which are currently used) may be assigned a particular turn or information as shown.

Segmented Display

The above features could be considered for providing an efficient and informative VTIS by the use of Tri-Coloured LEDs (Red / Amber / Green) and a segmented display system with each segment housed by multiple LEDs to generate the sufficient light intensity for effective visibility. The suggested patterns for indication of different turns are as shown.

Currently the turn indicator lever has a spring-loaded function to flash a few times on release or as long as the lever is held in a position, short of the extremes which result in indicating the respective turns, to indicate lane changing information. Spring loaded function can also get activated accidentally without the knowledge of the driver by the movement of the hand for any other purpose. The lane changing intention would be known to the driver wanting to communicate to other road users but the driver of the following vehicle would not know the real intention. Because the signal disappears after a few flashes and even before the completion of the lane changing process. The driver of the following vehicle assumes it be an accidental indication for it displays the same colour as that for turns. This confusion can be eliminated by displaying the arrow patterns in different colours to communicate the lane changing information and others, such as pass or dangerous to pass.

Additional Functions of Segmented Display

Currently the hazard indication is through the flashing of amber (yellow) lights. The same indicator is used whether the hazard is because of a parked vehicle on the kerb side of the road or stalled anywhere on the carriageway, or even one that is moving.

Segmented display system suggested earlier could be used to communicate different levels of hazard, the displaying vehicle may cause to other road users. The colors amber and red can be used to indicate the increasing level of risk generated by the displaying vehicle or the increasing level of caution other road users need to exercise.

Parking on the kerb side could be for reasons ranging from personal to repairs such as change of a flat tyre. The second reason could exhibit greater risk to other road users as compared to the first one. Thus the two situations could be distinguished by the use of the patterns as indicated here. The letter “P” display suggests the first and ‘X” in red along with amber “P” suggests the later. That is parked for reasons of repair and the work is in progress.

A vehicle in motion can develop a snag and get stalled on the carriageway. This situation is different from that of a parked vehicle on kerbside and poses greater risk to the other moving vehicles. On some occasions the stalled vehicle may have to be repaired at the stalled location even before it is moved to the kerb side. In such a situation the patterns suggested could be displayed to communicate the appropriate message to other road users. The first one suggests the need of assistance for moving the vehicle to a safe place through the amber “+” sign in the red box. The red “X” in the red box in the second suggests that the repair work is in progress before moving the stalled vehicle to a safe place or rectified for normal operation.  The amber arrows on both sides, of the two indicators, suggest other road users to move cautiously from any of the sides subject to space availability.

A vehicle in motion can exhibit different levels of hazard conditions which are external to it or those concerning it itself. The external reasons, for example could be due to weather conditions or traffic restrictions ahead necessitating the leading vehicle to move cautiously and the same need to be communicated to the following vehicle. These types of cautious movements could be communicated through flashing amber indicator. The reasons concerning the vehicle itself could be failure of brakes or lights or any other but necessitated the movement of it to transfer it to a safe place for repairs. Such hazardous movements could be communicated through a flashing red indicator.

The three hazard types with two states each could be communicated through a hazard switch with three buttons for each of the three types. The buttons should have double press option to choose each of the two states for the three types of hazards. A fourth button cancels any of the six options chosen.

Normally the backing of vehicle is communicated by white lights in the rear side of a vehicle. This is understood more by convention than a clear indication of the intended movement. This intention could be more effectively communicated by the display of the pattern suggested. Amber is suggested for the risk is low as the vehicle normally moves slowly in this movement.

The patterns suggested earlier for various turns and hazard indicators could also be displayed using an LED Matrix. It would be appropriate to examine, which displays better, the segmented display or matrix display and adopt the optimal.

Tail and Brake Lights

Currently tail and brake lights are displayed in red either by separate sets of lights for each of the two functions or by a single set with relatively dim light indicating tail lamp and brighter indicting application of brakes. To eliminate or reduce any confusion caused by the same colour light for both functions, a third red light is displayed at the top (or bottom) on the rear wind shield for indicating the application of brakes. This third light does not glow when only tail lights function is on. In some automobiles increasing intensity or size suggests emergency application of brakes. This arrangement still does not clearly communicate the real message the leading vehicle would like to inform the following vehicles.

The purpose of tail light is to indicate the presence of a moving vehicle ahead and that of the brake light is to suggest the slowing of the vehicle ahead or stopped state of the vehicle ahead. Of the two, the slowing state or stopped state of the leading vehicle exhibits greater risk to the following vehicle due to reducing gap between the two. In an emergency the gap reduces faster. It would be prudent to use different colours for the functions to indicate the different risk levels. Amber could be used for tail light and red for brake lights. Since these colours are also used for displaying different turn patters, the shape for tail and brake lights can be circular as against rectangular shape for the turn indicators. A set of three lights with four states to suggest the presence of a moving vehicle or a stopping (including emergency stopping) vehicle can be considered by using two-coloured (amber/red) LEDs. Progressive reds indicate the degree of braking.