London Bus Routes Surveyed

Tait has developed an innovative surveying application to optimise the performance and coverage of the London Bus radio network.

Using GPS satellite technology, Tait Custom Integration's application enables Tait Europe to collect and analyse radio behaviour by driving the routes covered by the London Bus MPT 1327 trunked network.

A GPS receiver is connected to a customised TM8255 mobile radio in a Tait Europe vehicle. A lucky Tait Europe engineer then drives the London Bus routes, and plots GPS points on an online map to indicate where coverage is weak or where the radio changes sites.

Network coverage goes under the microscope

Tait Europe Regional Engineering Manager Geoff Shirley says while it is early days for the use of the application, with only two of the 10 network sites currently installed, the tool has already been put to good use on London roads.

"The surveying tool is being used as a benchmark - once the survey of a bus route is completed we have a measurement of how good the coverage is. Then, if there are any issues in the future we can get back and redo the survey and confirm any degradation in coverage," Mr Shirley says.

"There are some 544 bus routes in London, covering 6,810 kilometres of London roads. London Bus requires our trunked network to cover 95% of all bus routes, and to date we have covered 96% of the 133 routes we have surveyed," he adds.

Radio parameters adjusted for optimal coverage

TCI Software Team Leader Malcolm Forbes says the surveying application helps to optimise radio parameters so they switch sites at the right time and place.

"If the radio is switching sites too often, this can cause loading problems due to the increase in MPT signalling. If the radio is switching sites too late, this can cause poor reception and call failures. There are a number of parameters in the infrastructure and mobiles that can be adjusted to achieve an acceptable balance," Mr Forbes says.

A PC application collects the radio data and converts this data into a suitable file format that can be easily displayed as a plot on an online map. Radio data collected includes standard GPS information such as latitude, longitude and time, as well as radio channel number, radio site signal strength and error rates.

Google Earth is being used as the mapping software for the application, enabling Tait Europe to plot their data on a realistic map that shows landmarks such as buildings and trees. Plotted points are colour-coded according to signal strength - green for good, blue for marginal and red for bad.

"The application is being used to optimise network coverage and performance now, so the radios to be installed in London buses can be programmed correctly the first time - avoiding any costly reprogramming at a later date," Mr Forbes says.