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Sat Nav and GPS devices

Can I use my in-car satellite navigation device (satnav) for walking?

Most in-car satellite navigation systems are designed specifically for navigation whilst driving. However, hand-held GPS systems are also available that are designed for walking and some systems are a combination of the two.

Why do postcode searches and satnavs return the wrong location for an address?

Royal Mail define a postcode as a group of numbers and letters that give precise and essential information about a mail item’s destination.

Postcodes often cover several different addresses and a satnav or online search tool may only direct you to a dot or marker arrow in the postcode area (known as a centroid), rather than an individual property within it. The centroid only gives an average position for addressable properties within the same postcode and is not an exact referencing calculation for each address.

To create a centroid Ordnance Survey takes the individual addresses supplied by Royal Mail and gives them co-ordinates. This information is combined with the sector boundaries prescribed by Royal Mail to form our Code-Point and Code-Point Open products. A mathematical algorithm is used to produce the centroid and this is then located on (or snapped to) a property close to the centroid.

Thus in an urban area, where you see houses in the same street sharing a postcode, the centroid is likely to be near all properties.

In a rural setting, however, the centroid may be quite a distance from some properties that share a common postcode, since the average position is spread across a wider geographical area.

My property has recently been built; why can I not find it in my satnav system?

Not all satnav devices are supplied with the most recent road and address mapping and your device may need updating. You should contact the satnav manufacturer/supplier about mapping updates.

Ordnance Survey makes detailed maps for the whole of Great Britain of all new roads and addresses within six months of them being built and this mapping is available to all mapping companies under Crown copyright licence.

Why does my satnav display the incorrect route?

Satnavs take into account many factors including your current position, your destination and the road network to calculate a route and they can choose one that does not suit you or a particular journey. Please check your satnav settings to make sure it reflects the choices you want your satnav device to make in its route calculations.

Very few routes are incorrect – many satnavs are unable to take account of real-world problems like traffic jams and road-works – and as such it is possible that a less desirable route may be suggested.

The correct classification (motorway, A road, B road etc) and mapping of a road is important in route calculation and an ‘incorrect’ route may be calculated if a road classification is wrong or out of date. Road classification is most often the responsibility of your local council.

Ordnance Survey does not recommend routes or that any particular route is faster or slower than another.

How accurate are sat nav systems?

GPS positions have an accuracy of around 5-10 metres on the ground and 10-20 metres in height. There are many factors that can lead to the distortion of GPS signals, such as orbital errors, physical obstructions (tall buildings or trees) and bad reception.

Why are the maps on my satnav receiver incorrect?

Not all satnav devices are supplied with the most recent road and address mapping and your device may need updating. You should contact the satnav manufacturer/supplier about mapping updates.

Ordnance Survey makes detailed maps for the whole of Great Britain of all new roads and addresses within six months of them being built and this mapping is available to all mapping companies under Crown copyright licence.

Which of your maps are used in satnavs?

As the national mapping agency of Great Britain, Ordnance Survey has an extensive range of digital maps and a number of these have been used by satnav manufacturers and their suppliers. However, not all mapping in satnavs is supplied by Ordnance Survey and some manufacturers map themselves or take mapping from other suppliers.

Ordnance Survey markets a suite of maps within its OS MasterMap portfolio, which includes, very detailed road and address information including road classification, trunk roads and primary routes, named and unnamed minor roads and local streets, information on height, weight and width restrictions, traffic calming, turn restrictions, one-way roads as well as vehicular access and time restrictions.

I am being directed along an incorrect route. Please can you amend it.

Satnav manufacturers design their products, including how their device will make its routing calculations. You should contact your supplier if you are concerned about a routing suggestion provided by your device. If you believe that a road has been misclassified, which has led to mapping errors and inappropriate routing suggestions, you should contact your local authority.

Who do I need to contact if the mapping on my satnav is incorrect?

Please report all errors to the private mapping companies directly. Two market leaders are Navteq and Tele Atlas. Both companies have reporting systems on their websites enabling users to report problems. The following links may be helpful:

Tom Tom

Navteq

Why are satnavs sending heavy vehicles down tiny unsuitable roads?

Sometimes, large commercial vehicles have a completely legitimate need to drive along smaller roads – for a goods delivery, for example. This sort of routing is more problematic when drivers use satnavs that are unsuitable for their specific vehicle.

Ordnance Survey recommends that all commercial vehicle drivers use a satnav that is appropriate for their vehicle. Some satnavs are designed specifically for the car market and the device will calculate a route suitable for cars and not take any account of the vehicle it is actually being used in.

To make the best use of satnav, it is important that all drivers ensure that the most up-to-date mapping is installed on their device.

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