Using sensor networks to speed up accident response

On Sept 29th, twenty six people died  when an air conditioned coach of the Bangalore-Nanded Express caught fire.

According to the media, Indian Railways is cash strapped. It cannot afford expensive fire fighting equipment. The other major problem is maintenance. Even if expensive equipment is installed, poor maintenance will render the equipment useless within a short time. Indian railways transports over 25 million people daily. Shouldn’t it be the world leader in railway technology and related aspects such as safety, accident response etc by now ?  The only thing which has changed over the years is that the passengers these days have expensive smart phones. You would not know it is 2014 otherwise since our trains are still as filthy and unsafe as ever.

There is scope for cheap low power wireless sensor networks to help in quickly detecting fires and relaying the information to the train driver and other personnel.  In the event of a fire on a moving train, it is really important to stop the train since air movement helps spread the flames. On a moving train the fire can quickly move from one coach to another. Further, passengers can get killed or seriously injured when jumping out of a moving train.

In India, trains have an alarm chain which can be pulled to stop the train. This mechanism is prone to failure. In this particular accident, the passengers were not able to alert the train driver to the fire. Quoting the Indian express – “Though the attempt to halt the train failed, it was a call by a passenger to the Bangalore control room that saved many lives. The officials at the control room alerted their counterparts at Puttaparthi, who notified the driver “.  Imagine if the train had caught fire in the countryside outside of cellular network coverage.  Lot more lives could have been lost.

A simple low power wireless network can be installed on trains to notify the driver. This can be used alongside the existing chain system. As a first step, low power wireless nodes can be installed on the roof of every coach.  This network of nodes can relay an alarm message in a matter of seconds to the train driver.  Since the radio on these nodes will be active all the time, these need to be solar powered.  Wireless alarm buttons can be installed inside a coach in different places. These battery powered alarm buttons will then communicate with the nodes mounted on the roof. The latter will relay the alarm to the driver. Since low power wireless nodes can be really cheap in volumes, the roof top network can have a high degree of redundancy to make sure that any alarm message always makes it to the driver. To cut down on misuse, the alarm button can be equipped with a camera which can help in identifying the person who pressed the alarm button.  The next step will be to install wireless sensor nodes equipped with different sensors for measuring temperature, humidity, carbon monoxide, carbon dioxide etc. These sensors will keep monitoring the environment in the coach and raise an alarm in the event of a fire. The roof top network can then relay the alarm to the driver. If the train is equipped with GPRS / satellite links etc, the alarm can also be sent out.

The problem with the chain system is that the driver does not know if there is a genuine problem or not. Train drivers even disable the alarm system when passing through areas prone to misuse of the alarm system. When sensors are deployed inside coaches, the driver will have enough information (smoke, temperature etc) to decide on the course of action. One more advantage is that the wireless sensor network can periodically self test to make sure all coaches are being monitored properly.

The sensor nodes inside the node need to be recharged periodically (once in a few months). Theses sensor nodes can be made available for purchase to the general public.  Passengers can bring their personal sensor nodes on the train and switch them on  at night before going to sleep.  The personal sensors will join the train’s network. At the end of the journey passengers take their personal sensors with them. Sensor nodes can optionally have a bluetooth interface and can use this to send alarms to all cell phones within range. Cell phones can then wake up the passengers as well as send information to the railway authorities using the cellular network if it is available at that time/location.


Posted on January 4, 2014, in Uncategorized. Bookmark the permalink. Leave a comment.

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