COLLISION AVOIDANCE SYSTEM (CAS)
1. Context
Most collision avoidance systems require two pieces of information: the locations of all the other vehicles and the location of this vehicle relative to those vehicles
2. What is a Collision Avoidance System(CAS)?
- A collision avoidance system (CAS) is a safety technology designed to prevent or reduce the severity of collisions in vehicles, aircraft, or other moving objects. It uses sensors such as radar, lidar, cameras, or ultrasonic sensors to detect potential obstacles or hazards in the path of the vehicle or object.
- When a possible collision is identified, the system can take various actions, including alerting the driver or operator, automatically applying the brakes, steering to avoid the obstacle, or taking other evasive measures.
- These systems are commonly found in modern automobiles as part of advanced driver-assistance systems (ADAS), and in aviation, where they help prevent mid-air collisions between aircraft.
- The goal of a collision avoidance system is to enhance safety by reducing human error and reacting faster than a human could in dangerous situations
3. Does CAS help land-based vehicles?
- Vehicular traffic is an essential part of modern life, leading to the creation of numerous transportation options and their deployment in various environments. Today, we experience traffic not only on roads but also in the air, across water bodies, and even in space—a questionable indicator of progress.
- Since it is not feasible to significantly reduce this traffic, collision avoidance systems (CAS) have been developed as a safety measure.
- Consider two cars, referred to as the Front Car and the Back Car, both equipped with CAS devices. Typically, the Back Car monitors the speed of the Front Car, the distance between them, and its own speed.
- If the gap between the two cars is predicted to decrease to a certain threshold within a specified time, the CAS may automatically engage the emergency brakes—such as those required in the European Union—without the driver's intervention.
- To accomplish this, the CAS must be connected to the Back Car's braking system and capable of overriding the driver’s commands. It also needs to be linked to the car's speedometer and equipped with sensing technology like radar, lidar, or cameras with object recognition to track the Front Car
4. What is 'Kavach' System?
- A recent series of train accidents in India has drawn attention to the slow rollout of ‘Kavach,’ the indigenous collision avoidance system (CAS) for Indian Railways. While Kavach shares the same basic functions as CAS in automobiles, the railway system's complexity makes its implementation more challenging.
- Kavach consists of three key components: onboard systems, trackside infrastructure, and communication networks. These can be reclassified into three categories for clarity: computers, communications, and control.
- Computers: There is a computer onboard each train, as well as two additional computers for station masters. One of these, known as the master computer, gathers and processes data from signals and interlocking points and sends its output to the locomotive computer. The other computer, the remote interface unit, also collects and processes information from various points on the railway network but transmits its data to the master computer rather than directly to the locomotive computer.
- The locomotive computer receives data from two additional sources: (i) two Radio-Frequency Identification (RFID) readers mounted underneath the train, which scan RFID cards embedded in the tracks at fixed intervals to determine the train's location and track ID, and send this information to the onboard computer; (ii) communication between onboard computers of nearby locomotives.
- Combined, this system enables communication between stations and train pilots, aids pilots in decision-making (even without visually spotting another train), regulates speed, issues alerts in areas with low visibility, and automatically applies emergency brakes when a collision is anticipated.
- Communication: The remote interface unit transmits data to the master computer through fiber-optic cables. The master computer communicates with the locomotive computer via ultra-high frequency radio. The onboard computer uses GSM-Railway to interact with the overall network management system, which powers the Kavach CAS, and authenticates communications with nearby master computers and locomotive computers.
- Control: Similar to cars, the onboard computer is linked to various parts of the locomotive, including the braking system and an alarm system to alert pilots. While operating the train, pilots use a specialized interface, such as a digital screen, to receive information from the computer and provide inputs. The station master has a similar interface with the capability to send emergency messages as needed
5. Does CAS help in ships and aircraft?
- The Traffic Collision Avoidance System (TCAS) for aircraft also operates on a computer-communication-control framework similar to that used in trains. A crucial component of this system is the transponder, a device that responds when it receives a radio-frequency signal. By utilizing the transponders of other nearby aircraft, the host aircraft can generate a 3D view of the surrounding air traffic.
- A key feature of aircraft CAS is the alert system. If another aircraft is detected to be on a potential collision course within 48 seconds, the system issues a traffic advisory, prompting the pilots to visually locate the other aircraft.
- If the potential collision is less than 30 seconds away, the system escalates the alert, requiring the pilots to take action: they must report the situation to air traffic control and, if necessary, maneuver the aircraft to avoid the collision, even if this contradicts air traffic control’s instructions. Once the danger has passed, the pilots are expected to return the aircraft to its original course.
- Additionally, aircraft may be equipped with radar altimeters to measure the distance to the ground, as well as systems to alert pilots to tall obstacles like towers and antennas.
- Similar to aircraft and cars, ships use a combination of visual sightings and radar to avoid collisions. This process is supported by additional systems such as AIS (Automatic Identification System) and LRIT (Long Range Identification and Tracking). AIS involves land-based stations tracking data from transceivers on ships to determine their location, speed, and direction, and then transmitting this information back to the vessels.
- LRIT requires ships on international voyages to report their location, local time, and onboard equipment status every six hours to the authorities of the country under whose flag they are sailing.
- This data is then shared with other contracting governments and operators of search-and-rescue missions via the International LRIT Data Exchange, as mandated by the International Maritime Organization
6. Sattelites and CAS
- An alternative to the transponder-based system for aircraft is the Automatic Dependent Surveillance-Broadcast (ADS-B) system. This technology gathers and processes information broadcasted by each aircraft through satellites to determine the relative position, heading, and speed of multiple aircraft. Similarly, ships can benefit from satellite-assisted Automatic Identification Systems (S-AIS) to track vessels that are out of range of land-based AIS stations.
- The introduction of the U.S. Global Positioning System (GPS) revolutionized navigation and collision avoidance globally, with some countries enhancing it with their own systems to meet specific national requirements. For instance, India plans to use its NavIC satellite constellation to support road and railway traffic management.
- In the Front Car + Back Car scenario, if the country has a GPS-tagged database of traffic elements like stop signs, turns, signals, and intersections, the CAS in the vehicles can be supplemented with GPS data.
- Although civilian GPS accuracy is limited to about 10 meters, which is insufficient for collision avoidance systems, this limitation can be mitigated with differential GPS technology, which can enhance the accuracy to less than a meter
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For Prelims: Automatic Train Protection (ATP) system, KAVACH System, Research Design and Standards Organisation (RDSO), Safety Integrity Level-4 (SIL-4) standards, Signal Passed at Danger (SPAD), Traffic collision avoidance system (TCAS), and Radio Frequency Identification (RFID).
For Mains: 1. The Indigenous train collision avoidance system also known as the automatic train protection system or Kavach, is to help the railways to achieve the goal of Zero Accidents. Comment.
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Previous Year Questions
1.Consider the following communication technologies: (UPSC CSE 2022)
Which of the above are considered Short-Range devices/technologies? (a) 1 and 2 only Answer (d) 2.“Kavach” system introduced by Indian Railways is a/an ______(SSC CHSL Tier I 2023) A.Insurance scheme for passengers B.Automatic crossing system C.Automatic Train Protection System D.System to increase the speed of the trains Answer (C) |
Source: The Hindu
