Types of Traffic Signals – What is the first thing that comes to your mind when you hear the civil engineering subject? The one who disturbs the rhythm of your journey without your permission, right? Jokes apart, it plays a relevant role in the traffic management of the country. Traffic signals regulate the movement of both vehicles and pedestrians by assigning priorities to various traffic movements. Being wide and heterogeneous in nature, it is not a cakewalk to control the huge population including you and me.
Now, before we get into the details, let me tell you that traffic signal types and traffic signs are not the same!
Traffic signal vs Traffic sign
There is often a misconception that traffic signals and signs are the same. But the truth is that both are traffic control devices, but different. Traffic signs are placards provided to guide you in the journey whereas signals are placed only at the main intersections to manage the traffic.
For example, imagine a junction where heavy traffic is found usually in the north-south direction. Likewise, iIf there is not much traffic in the east-west direction, traffic signals are not required at the junction. Yeah, simple logic.
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The importance of traffic signals
Growing traffic density and insufficient expansion of available road space have resulted in congestion and related delays during peak hours on urban roads around the world. This in turn, results in increased travel time, which reduces the performance of the transport network. This problem is more serious on urban roads with frequent intersections, which are the main points of conflict for traffic movements. Traffic signals at the main intersections can curb the situation.
Mechanism of traffic signals in India
The design of signals will be such that it shows a green light where there are less traffic and a red where there is more traffic. It also considers the pedestrians who may cross the road in between and allots a minimum of 10 to 15 seconds for that. Another interesting fact it considers is that the overall waiting time should not exceed 120 seconds in normal situations, which is the average tolerance level of humans.
Advantages of traffic signals
- Provide orderly movement
- Minimises the number of conflicting movements
- Increase capacity
- Interrupt heavy traffic to allow other traffic to enter or cross
- The coordinate continuous movement of traffic at the desired speed
- Promote driver confidence
Okay. Let’s see the varieties now.
Types of traffic signals
Traffic signals play a relevant role in the traffic management of the country. Furthermore, traffic signals regulate the movement of both vehicles and pedestrians by assigning priorities to various traffic movements.
Types of traffic signals are broadly classified as follows.
- Traffic control signals
- Pedestrian signals
- Special traffic signals
Traffic control signals
The traffic signal is based on light signals that come in three different colours: red, yellow, and green. Red to stop, green to go and yellow to get ready. Obviously, you have seen the rangoli of colours in your life.
Traffic control signals are further divided into three types based on the working mechanism.
- Fixed time signal
- Manually operated signal
- Traffic actuated signal
Fixed time signal
Fixed time signals are programmed to cycle through red, amber yellow, and green lights on a regular basis. Generally, these signals operate at fixed time periods without considering the real-time traffic. Fixed-time signals are the most basic type of electrically operated automatic traffic signals.
The main problem with Fixed time signal is that, the cycle of red, yellow, and green continues regardless of whether there is traffic on the road. Evidently, traffic in the heavy stream must come to a halt at the end phase.
Manually operated signal
The manually operated signal is a human-operated traffic signal, as the name implies. In this case, the traffic cops monitor the flow of traffic and adjust the timing of the red, yellow, and green lights as per traffic flow. These types of signals are manually operated and hence are reliable.
Traffic actuated signal
In the case of traffic-actuated signals, the timing of the traffic light cycle is based on traffic intensity. Similarly, this includes semi-actuated and fully-actuated signals. Moreover, the timings are real-time.
Pedestrian signals
Generally, pedestrian signals are for pedestrians who cross the road/intersections or walk along the footpaths. Hence, for ensuring a smooth traffic flow, traffic control and pedestrian signals should work in tandem.
Special traffic signals
All other signals which don’t come in the previous categories belong to this type. Special type of traffic signals serves as a warning sign to vehicles to slow down before entering the intersection. They are also known as flashing becons.
Types of traffic signals in India
Let us have a small introduction to the Types of Traffic Signals in India. The whole system of traffic signals in India is divided as follows.
- Simultaneous system
- Alternate system
- Simple progressive system
- Flexible progressive system
We have seen different faces of signals. Now, let me get you the warrants for traffic control signals.
Warrants for traffic control signal
1. Minimum vehicular volume warrant
Case 1- The average traffic volume for 8 hours on both approaches should be at least 650 vehicles/hr on major streets with a single lane and 800 vehicles/hr on streets with 2 or more lanes.
Case 2- Minor street (One direction at least 200 veh/hr- single lane
250 veh/hr- two lanes
Case 3- >60kmph, 70 per cent increase in a major case
2. Interruption to continuous traffic flow on a major street with 1000- 1200 veh/hr that there is undue delay or hazard to traffic on minor roads with a traffic 100- 150 veh/hr in one direction only during any 8 hours on an average day
3. Minimum pedestrian volume movement
4. Accident experience warrant
5. Combination of warrants
Lastly, in areas where there is huge traffic, ramps are preferred. But ramps are not suitable for heterogeneous traffic through some of the planned cities have implemented them. Accordingly, It is better to use flyovers and over bridges in these cases.
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