Sunday, February 22, 2015

DRONES AND RAILWAYS: USING UAVs FOR RAILWAY TRACK SURVEILLANCE.

The Indian Railways has a category of employees called Trackmen (or Gangmen). The Gangmen, so called because they work in groups or Gangs, are concerned with the safety of the Tracks on which 19,000 of India's Trains run.  Every day in India, almost two hundred thousand gangmen walk through the 1,15,000 odd kilometres of railway tracks[1]. They do this in an effort to survey the tracks.

Railway Tracks needs regular maintenance to remain in good order, especially when high-speed trains are involved. Rails contract in cold conditions and may fracture. They expand in hot conditions and may buckle. Or they may get corroded/corrugated or damaged due to Rail-Wheel interaction. As trains move, ballast is crushed/moved by the weight of trains passing over it, periodically requiring re-levelling ("tamping") and eventually cleaning or replacement. If this is not done, the tracks may become uneven causing swaying and rough riding. All these factors (and others) may cause derailment of trains. Inadequate maintenance may lead to a Speed Restriction being imposed to avoid accidents.

Track maintenance is hard manual labour, requiring teams of labourers, trackmen or Gangmen. On finding any fault with the tracks, the try to correct it then and there. If repair is not possible, they alert the railway administration on the nature of the problem and get it corrected.  It is partly because of their toil and hard work that passengers roaming on the vast Indian Railway network have a largely accident-free travel experience. They go about maintaining the tracks, be it in intolerable heat of Indian summer , or the insufferable Himalayan winters.

Every year about 400 gangmen are run over by trains while working on the rail tracks[2]. Several hundreds of them suffer injuries or incapacitation. Many of them also suffer from the chronic diseases due to the nature of their work. Truly, they are the unsung heroes and a great asset of the Railways and also the Nation. But unfortunately, inspite of the Gangmen's hard work and efforts, accidents do happen.

I believe that technology not only alleviates troubles but also prevents problems from occurring in the first place. Therefore, in order to reduce the Burden on the Gangmen and increase their efficiency and output we must take the help of technology. One such important innovation that can help the Indian Railways is the use of Drones (Unmanned Air Vehicles- UAVs) for Track and traction (including electric lines) surveillance.

It may appear unusual as to how UAVs can be used for Railway track surveillance. But think a little deeper and it becomes obvious that UAVs are the natural choice to survey Railway tracks in the 21st century.Drones are already used to inspect Powerlines and Pipelines. The production side of oil and gas exploration and production entails the monitoring of the integrity of oil and gas pipelines and related installations. For above-ground pipelines, this monitoring activity is performed using digital cameras mounted on one or more UAVs [3].

How can we go about using UAVs for Railway track surveillance?
Imagine this scenario. A drone takes off from a nearby drone base (for Railways). It has within itself Radar, Infrared and Ultrasound transmitters and sensors. As it flies along a pre-set path (or flown by a controller) it continuously sends out Radar, Infrared and Ultrasound waves towards the tracks. These waves get reflected from the track Rail, sleeper and ballast and is received by the receiver on-board the drone. Now the data collected is quickly analysed. By comparing the outgoing pulse with the returning echoes, computer systems can produce detailed picture of the tracks. Any defect or unusual occurrence with respect to track- rail/sleeper integrity is detected and the nearest technician/Gangman is alerted. He/she will approach the spot and try to get the anomaly corrected.

For the drone to analyse the Radar, Infrared and Ultrasound waves it receives, it will have a template to which it can compare the received data. This template is nothing but the radar, infrared and ultrasonic signature of the normal intact track in that place at that time. For this purpose, extensive research to collect and feed normal track data is required. This can easily be done by using the large and relatively inexpensive technical manpower at the government's disposal involving government and private entities.

The drones can also be used to survey electric traction lines running above the railway tracks. Moreover the drones can also be used in search and rescue missions during disaster and accidents.
The various advantages of using drones for railway track surveillance-
1) Very quick, reliable and objective assessment of track structure.
2) Real-time surveillance of track structure for improved safety and quick repair.
3) Reduction in the burden of responsibility on gangmen and railway staff. This will also reduce fatalities of patrolling gangmen and provide better working conditions for railway staff involved in track surveillance.
4) A very reliable and real-time surveillance is possible. As a precursor to quick surveillance for High-Speed Railway, (which will soon be a reality) drones may be a technological solution.
5) Development of technical know-how and expertise which will have several civilian and defence spin-offs.
6) it will provide employment to a large number of people like engineers, drone experts and electronics professionals.
7) when any defect is detected and a railway staff rushes to the spot to correct it, the track can be surveyed post-repair also in real-time.
8) as mentioned earlier, drones  can also be used in search and rescue missions during disaster and accidents. Infact, the drones may be the first to reach and report about the railway accident in a remote area.
9) This area will become an excellent interface for civilian-defence co-operation as the military has drone expertise.

Advantage Of Drones Vis-A-Vis Track Machines
There are machines called track machines which run on the railway track in question. As they move along, they test rail sensitivity using specialised sensors on-board. If defects are found, the crew on the track machines correct the problem then and there, if possible. One may then ask, as to why we need drones for surveillance when track machines do an almost similar job. The answer is that there are several inherent advantages in using drones like-
A) When a track machine is on the line inspecting the track, no other train (passenger or freight) can use that path. This is known as working in a block. It means that when repair and maintenance is going on, no other train can run on that path. This leads to congestion and slowing of movements on that section of the track. More  so if the track in question is a very busy one- as on Indian Railways. By using drones, we can totally do away with working in a block. This will allow for optimum utilisation of resources and better running of trains.
B) Track machine, particularly those used for inspection purposes, have been involved in a number of serious incidents, including deaths. Factors leading to derailment include failed locking equipment, wheel failure, damaged rail wheel support systems, and uneven or over-loading issues. Moreover, track machines have to carry heavy rails, sleepers etc when they may not be needed. Drones do not have this disadvantage.
C) Track machines unlike drones, cannot be used for search and rescue in case of accidents like drones. Though they can be used for restoration and repair.

Assuming that each drone can survey about 50-75 kilometres of tracks a day, the whole of the Indian Railway Network (64,000 route kilometres) can be surveyed by around  a thousand drones. Drone stations can be set up in every railway division.

It must be remembered here that drones are in no way a replacement to Gangmen or railway staff. After the drone has detected any track fault, it has to be corrected by human hands under human supervision. Drones can never replace that. Drones are only meant as a way to reduce burden on the hard working Gangmen and to improve safety and efficiency.

Drone technology may be expensive at present and initial investment may have to be intensive. But in the long run there is no price too heavy to be paid where human life and safety is involved. Critics of India's space program (in the early days) had argued that it was too expensive for a country like India. But recently, it was ISRO's satellites that correctly predicted the path of cyclone Phailin that hit the Odisha coast. Because of the warning (by ISRO) people were evacuated from the path of the cyclone and sheltered in safety. This led to minimal casualties. India's space program more than paid for itself. Drones will fulfil a similar function and greatly improve our safety and efficiency outlook in train running.

REFERENCES
[1]- http://www.livemint.com/Politics/p5JjFgtzbkcY3uVk5mmvjL/Railways8217-vulnerable-gangmen.html

[2]- http://www.skyscrapercity.com/showthread.php?p=100678973

[3]- http://www.barnardmicrosystems.com/about/papers_&_presentations.html

                                                                                              
                                                                  -Dr.Kartik Hegadekatti.

Dr.Kartik Hegadekatti is an Indian Civil Service officer presently serving in the Ministry of Railways in India.Views Expressed are Personal. 

2 comments:

  1. Sir why Drones? I guess if we fix the sensors at static places ..it should serve the purpose since lines are static nothing changes so dynamically .

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