PRESENTED B Y ROHIT KUMAR EC E 4 th YEAR

INTRODUCTION Speed cameras were introduced in west London in 1992 and following their success in reducing speed related crashes and injuries their use expanded to many other areas of Great Britain. The equipment is expensive to buy, operate and maintain and their support in prosecution procedures also much substantial administration costs. However and the cost are small compared to the benefits of society and the economy.

NEED OF SPEED CAMERA Although there is good road safety performance, the number of people killed and injured on our roads. So the roads safety strategy was published or introduced to support the new casualty reduction targets. The road safety strategy includes all forms of invention based on the engineering and education and enforcement and recognizes that there are many different factors that lead to traffic collisions and casualties. The main reason is speed of vehicle. We use traffic lights and other traffic manager to reduce the speed. One among them is speed cameras. Speed cameras are recommended under use to reduce road casualties. Since these cameras save lives of road users the speed camera is also known as" safety cameras".

BASIC PRINCIPLE Speed camera uses the basic principle of Doppler Effect and RADAR technologies.

RADAR PRINCIPLE A radar uses electromagnetic waves to detect objets and provide informations about them (distance, speed). The radar sends radio waves (electromagnetic waves) at a given frequency and listens for their return (echo). If an object is in the beam, some waves will bounce off it and return to the radar. By dividing the time it took for the waves to travel back and forth by the speed of the waves (the speed of light) it is then easy to determine the distance.

Fig. RADAR OPERATION

DOPPLER EFFECT To determine speed, radars use the doppler effect. They measure and scale the frequency variation between the radio wave sent and the radio wave received (echo). If the object is moving away, the frequency will be lower, if it is getting closer, the frequency will be higher. Depending on how much lower or higher the echo frequency is, it is possible to know at what speed the object is moving from the radar position.

The principle of this effect is well known in the study of sound.If the source of sound, emitting a note of frequency ‘f’ is move with a constant velocity 'V' relative to an observers, it is found that the observers p Perceives a sound having the frequency f' which differs from ‘f', being greater or smaller according to the source is move towards or away from observers. This phenomenon in sound was first explained by Doppler and hence the name Doppler effect.

DOPPLER EFFECT IN SPEED CAMERA The principle of speed camera that is the Doppler's effect can be described by the formula f M = 2vf E cos( α /c) Where F M if the frequency of the received signal v is the speed of vehicles f E if the frequency of transmitted signal α is the angle between the transmitted signal and path along which the vehicle travels c is propagation speed of the signal in the air.

HOW IT WORKS When the radar and the car are both standing still, the echo will have the same wave frequency as the original signal. Each part of the signal is reflected when it reaches the car, mirroring the original signal exactly. But when the car is moving, each part of the radio signal is reflected at a different point in space, which changes the wave pattern. When the car is moving away from the radar, the second segment of the signal has to travel a greater distance to reach the car than the first segment of the signal. If the car is moving toward the radar gun, the second segment of the wave travels a shorter distance than the first segment before being reflected. CONT…..

Based on how much the frequency changes, a radar gun can calculate how quickly a car is moving toward it or away from it. If the radar gun is used inside a moving police car, its own movement must also be factored in. For example, if the police car is going 50 miles per hour and the gun detects that the target is moving away at 20 miles per hour, the target must be driving at 70 miles per hour. If the radar gun determines that the target is not moving toward or away from the police car, than the target is driving at exactly 50 miles per hour. It checks if the measured speed exceeds the preset value and warns the police officer who are near by that of offenders has just passed or it activates the camera or flash gun.

What does the camera record? If a vehicle is detected speeding, a digital image of the vehicle is recorded onto a disk from which all details regarding the speeding vehicle can be extracted. The image clearly shows the colour, type, make and number plate of the vehicle. Fixed digital speed cameras have the capacity to measure speed in both directions. Digital images also include the following particulars: Date of the offence Time of the offence Location details of the camera which took the picture Direction of travel of the offending vehicle Speed of the offending vehicle Speed limit applying to the road where the camera is situated The lane that the vehicle was travelling within Other security and integrity parameters

CALCULATION OF SPEED You need the following pieces of information: Number of marks passed Interval between photos in seconds Distance between marks in feet You can calculate speed in mph as follows: Speed = Gap * Marks * / Interval Example: Suppose the vehicle passed 7 marks 5 feet apart in 0.5 seconds. Calculate as follows: 7 marks * 5 feet * / 0.5 seconds = 47.7 mph You may need the following conversion factors: Mph to feet per second: multiply by Feet per second to mph: multiply by Feet to metres: multiply by Metres to feet: multiply by

TYPES OF SPEED CAMERA Gatso meter cameras Truvelo Speed Cameras SPECS Cameras Traffic Light Cameras Mobile Cameras

Gatso meter cameras Gatso speed cameras - sited at the road side, Gatso speed cameras use radar technology to measure speed, a photo of the back of the vehicle is taken. Gatso speed cameras Annoyingly, they are clever little machines which can distinguish between different sizes of vehicles and can also enforce separate speeding limits - e.g. on roads where cars and vans are allowed to drive at 60mph, but HGVs are restricted to 40mph, it will be able to tell which is which, and enforce the limits accordingly.

Fig. gatso Camera

Fig. inside the gasto camera

Truvelo Speed Cameras It was invented by TRUVELO PVT. LTD US. By using an infra-red flash, the Truvelo camera avoids the flash that the rear Gatso cameras produce when a photograph is taken. This means that the driver doesn't see a flash but the camera can take a photograph of the driver, as well as the front of the vehicle.

Fig. truvelo camera

SPECS Cameras SPECS work in conjunction with the Automatic Number Plate Reading (ANPR) technology. These are the cameras that you often see fixed to gantries towering over motorways or larger roads. You might also see them on central reservations or on the roadside.. The groups of cameras are fixed at separate locations and work together to establish the average speed a vehicle is travelling at - by working out how long it took it to travel between each camera position.

SPECS conti. When a car goes past the first and last cameras (and any in between), the number plate details are recorded digitally. Using ANPR technology the video images of the number plates are married up, and the computer is able to work out which vehicles are speeding, and which are not. Fig. SPECS Camera

Traffic Light Cameras Cameras attached to traffic lights either work using radar technology (same as the Gatso), or from ground loops which are set into the road surface. The loop system works by activating when the lights turn red and if a vehicle passes over the road sensors after this time, then a photograph will be taken.

Mobile Cameras police use various hand held and mobile devices to catch out speeding drivers. They include the Mini Gatso and Laser Guns (Teletraffic or ‘hairdryers’) Mini- Gatso are just what they sound like, mini versions of the dreaded Gatso Cameras. Laser gun are hand held cameras that record a cars number plate on video film, so that the speed can be recorded. Fig. hand held Mobile camera

Fig. mobile camera in police van

WHERE SPEED CAMERAS ARE USED? areas where accidents frequently occur. areas where speeding is usually one of the main causes for the accidents. areas where human police controls are difficult.

HOW IT HELPS TO FIND STOLEN CARS? The vehicle is speeding. As it passes by an automatic radar, speeding is detected and a digital picture of the vehicle is taken. The picture is then sent to a national treatment center via internet networks (adsl connection). At the center the registration of the car is taken, as well as all the relevant data (time, speed, etc). The registration is compared to the database of stolen cars and rented cars. Police officers supervise this stage. The fine is then mailed to the owner of the car. A contestation is possible if the owner was not the driver

EFFECT OF RAIN OR FOG In general, the higher the frequency of the radar beam, the smaller the particles it can detect... Weather has almost "no effect" on the operation of those radars. Radars designed to detect moving vehicles use frequencies that are not reflected by small moisture droplets such as fog and clouds, or even precipitation. Very heavy rain can reduce the range of all radars, an effect called attenuation due to the signal being absorbed by the precipitation. In this case, weather conditions usually cause motorists to slow down to well below the speed limit anyway.attenuation

FUTURE SCOPE Automatic radars are or will be developped/improved to also control: Security distances between vehicles (work in progress). Respect of traffic lights (implemented).

CONCLUSION Now we would like to believe that enforcement cameras are there for our on good and make our roads safer. In general speed camera are perceived to be good idea because they protect innocent road users and pedestrians. Although these cameras reduces accidents and protects the innocent road users, the way in which the speed cameras are currently used is not to make the driver slow down, obey the speed limit and make the road safe but to catch and penalize the transgressors who may otherwise have slowed down if they have seen as the cameras in advance.

QUESTIONS?

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