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There are many different factors that affect the reliability of systems, categorised by

environmental and non-environmental.

1. (M1) 4 non-environmental factors would be;

Poor maintenance routinea poor maintenance routine, either not

maintaining the equipment regularly or not giving it a complete look over and

service when it is up for maintenance , would reduce the reliability of the

equipment. This is because without regular maintenance or inspection, little

faults that could easily be found and fixed could grow into larger faults with

time and cause the equipment to fail completely.

Installation by substandard workforcethis would significantly reduce the

reliability of the equipment as it would mean that it would not be set up

correctly from the beginning and could possibly be weak, so a tiny fault could

from the beginning could be made potentially bigger over time, leading to a

system failure. This problem would be especially large when exposed to

heavy vibrations, such as freight trains going past.

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Poor quality materialsuse of poor quality materials during the manufacture

of the equipment would reduce reliability as the would potentially be weaker

and not as accurate, therefore meaning that over a prolonged period of time

the equipment fall apart or break faster than a similar model made of high

quality materials.

Rodent infestationthis could damage the reliability of the equipment as

rodents can potentially get into the equipment and cause damAge by chewing

threw cables and building nests within it, meaning without proper maintenance

the equipment would be damaged by rodents living in it for a long time.

2. (M2) 3 Environmental factors would be;

High humiditythe reliability of electronic equipment is affected

significantly in high humidity areas, as by looking at the graph of time and

voltage output for sensors tested under different average humidity

conditions, the MTTR of a sensor in 50% humidity is 82500 hours,

compared to in 80% humidity the MTTR is 32500 hours.

Heavy rainfallheavy rainfall can affect the reliability as it can severely

reduce the range of the wireless link to the signal control room, which

would mean that the equipment would be useless. Heavy rainfall can also

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lead to flooding, which could potentially create short circuits and damage

the components. This would increase the failure rate of the sensor.

Terrain- the terrain would also affect the equipment as it would mean the

wireless link could be weakened by big hills or valleys, which would then

mean the failure rate for it would be significantly increased.