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GPS Software and Speed Warnings

Updated 0930 Friday 5th November 2010 UK time

November 2010: See "New UK speed data and upates to the software" below.

Robin Speed camera sign I set up this page in 2005 to support those experimenting with use of GPSS to provide automatic warnings when approaching speed traps or similar areas like schools, where you should take particular care.

e.g. "Speed Trap ! Watch your speed ! thirty six ! Speed limit is thirty !".

GPSS has had this capability since the product was launched in 1995, and this feature has been used in several countries by "enthusiasts". However, these pioneers had to find their own sources of data, and in some countries, the required lists of GPS locations are now becoming available for free use - rather than built into a product you purchase. Recent emails and a few 'phone calls made me take a fresh interest in this subject. In the short term it means more free data for download and addition to GPSS, to give warning of speed traps. In the longer term it may mean data becomes available for more countries, to provide automatic warning if you are exceeding a local speed limit or approaching somewhere like a school, where more care should be taken.

C4GPS K555GPS I certainly take no pride in both our cars having been caught by speed cameras, and I'm grateful to Thames Valley Police in providing these pictures to help resolve the dispute between June and myself on who was driving at the time. They didn't help - so do you expect me to argue with the wife ? Would you ? Yes, it's me who paid the fine and had points added to my license. I suppose if the council used a little more paint to remind us of the speed limits, there would be less risk of us breaking them - but then again, we would not have the opportunity to help subsidize car tax, would we ? :-)

Speed Trap data for GPSS on Laptops, Pocket PC and Smartphone

GPS Software on a Mio Pocket PC GPS Speed trap data is available for GPSS on Laptops running full Windows and GPSS on the Pocket PC and Smartphone
Note: when upgrading WARNING.TXT for GPSSppc, remember to delete any old WARNINGD.DAT made by GPSSppc.

I'm grateful to for making speed camera data available to GPSS. They have agreed to the data being included within the GPSS Baseline since v5.7. Updates are available from The licence conditions for those making use of the speed camera data are here. Sunninghill Systems have a licence to distribute copies of the data on and media such as CD/DVD and apply similar conditions regarding this data as those above.

The PocketGPSWorld site provides downloads of data in the required format. i.e. .CSV (comma Seperated Values) text files providing a list of longitude, latitude, and name:

GPSS looks for a file named WARNING.TXT in the above format, and if found, scans it regularly to provide automatic speed warnings. GPSS will also plot this data, in response to the "R" key, if provided in $LR.GTX in the GTX format explained on the addmap page. The latest GPSS Baselines now include small sample WARNING.TXT and $LR.GTX files. See "UK speed trap data from" below to add all the data.

If you know of public domain (free) speed trap locations for your country, please let me know. It might simply be free, or the owner of the data might give permission for it to be made freely available. I will then provide more information on this page. e.g. how to get the data in GPSS-compatible form. It is possible that the Freedom of Information Acts, such as that in the UK (FOIA 2005), will make more of this type of data freely available soon, and in the longer term this may extend to the locations of road signs which can also be used for GPSS spoken warnings.

Visit for the latest speed data for your country.

New UK speed data and upates to the software

On 5th November 2010 the SPEEDUK data was updated with the new data from Since January 2010, the data includes the direction in which the speedtrap applies. Our software was updated to exploit this capability.

New Zealand

Ian Wilde has kindly sent me this link providing speed camera locations in New Zealand:

Thanks to Tristan Burtenshaw for providing the above PDF file as text which you can download from speednz.exe This self-extracting exe expands into speednz.txt which you can use to replace warning.txt in the GPSS folder. The first line is the 20mph test trap used in the GPSS demonstration.

UK speed trap data from

Speed trap locations can be downloaded from

The information below will enable those in the UK to exploit GPSS with data off, and may serve as an example to aid those who are creating GPSS-compatible files from other data and/or countries.

Those who wish to exploit this capability in GPSS should

GPSS accepts the simple lon, lat, name format within the .CSV files that you can download from This data is read by GPSS from a single file named WARNING.TXT so you could create an updated version of this file simply by copying one or more .CSV files.

The GPSS Baseline only includes small sample WARNING.TXT and $LR.GTX ($LR.GTX is created from WARNING.TXT using SPEEDCAM.EXE held by Robin). UK speed data files based on November 2010 data, including GATSOs, Mobile and Red Light data, can be downloaded from SPEEDUK.EXE self-extracts into WARNING.TXT and $LR.GTX which should be put in the GPSS folder. This will also work with GPSSppc, the Pocket PC version of GPSS, which reads WARNING.TXT and creates WARNINGD.DAT for quicker startup. On the Pocket PC you should delete the old WARNINGD.DAT if changing WARNING.TXT yourself.

Visit for the latest speed data.


Speed trap location data could be exploited by old versions of GPSS if converted into one of the GPSS data formats such as GEO files. However, I thought it more straightforward to modify GPSS to accept data in the simple longitude, latitude, name format above, if provided with the file name WARNING.TXT

The latest GPSS.EXE logic does the following: if GPSS finds a file named WARNING.TXT it scans it regularly, and plays the sound file #SPEEDTR.WAV - "Speed trap ! Watch your speed !", followed by your speed in whatever units GPSS is running. e.g. mph or kmph, if:

Allowing for typical time lags, you can expect the warning to be given just as the camera sign comes into sight. e.g. maybe 50 to 100 yards. Spoken information is displayed, along with the name from the warning.txt file.
e.g. "Speed trap ! Watch your speed ! 36 ( GATSO:221 )"
- together with a picture of the speed camera sign from SPEEDCAM.BMP

If the data includes the speed restriction (e.g. @30) then this is also spoken. (e.g. "speed limit is thirty").

Speed cameras within 1000 metres of the car will flash on the map as small white squares - this is for testing "on the desk". A file SPEED.NME is also provided for Control-A REPLAY testing on the GPSS Baseline Ascot map. WARNING.TXT in the new GPSS Baseline will include an imaginary "test" camera on Sunninghill Hight Street at the 20 mph speed limit sign - to support the GPSS demonstration played before using a GPS.

You can now plot and search for "Speed Traps" by use of the R key, in the same way as you can search for UK petrol filling stations (F key), "Eating Places" (E key), etc, since 1995. We are replacing the little used "Railway Station" by "Speed Trap". You may find it easier to remember R by "Radar camera and speed trap".

So hitting R will select this data and GPSS will respond verbally with "Speed Trap". Hitting the Enter key would tell you the nearest speed trap.
e.g. "the nearest speed trap is 2 miles ahead at your 1 o'clock"

If you are using speech recognition software, you would just say "Speed Trap.... Search".

speed trap recording in GPSS and GPSSppc

GPSS supports recording of speed trap locations. I'd like to thank Erkki Koskinen in Finland for suggesting that we add this capability to GPSS, and then for testing it on the road. The purpose of this is to allow "enthusiasts" to create their own speed trap data. If others like can make use of this and distribute it to others, so much the better.

For safety, the GPS location is recorded if you hit ANY key on the keyboard. i.e, you do not need to look at the keyboard to do this.

To switch the recording on or off you do have to look at the keyboard - so please make sure you are NOT driving when you do this:
followed by Enter key.
When in this speed trap recording mode you will see the low left corner of the GPSS screem colour orange, instead of the normal grey colour.

Hitting any key will then write the GPS location into two files:
NEWTRAP.TXT in the format required to add to WARNING.TXT
NEWTRAP.GTX in the format required to add to $LR.GTX

a name is included based on the date and time. You may wish to edit this when you get home, and before you update WARNING.TXT and $LR.GTX.

In March 2009 this capability was added to GPSSppc, the Pocket PC version of GPSS. Details are in the user guide.