Transport for LondonIntelligent Speed Adaptation
On this page
- Digital speed limit map
- Intelligent Speed Adaptation
- How it works
- Benefits
- Next steps
- For developers
Digital speed limit map
One of the key challenges in realising a new generation of speed management systems is the ability to accurately let the systems know what the speed limit is across London. To address this challenge TfL have produced, and will continue to maintain, a digital map of all London's speed limits.
This will be made available free of charge to anyone who wishes to use the map for personal use, or to create commercial applications.
The map has been collected from a 'drivers point of view' and records the physical location of speed limit signs on the road network. Both terminal and repeater signs have been collected, with attributes used for distinguishing sign direction for double-sided signs. Collection involves recording only the actual sign records, which are later used to derive the speed limit for road lengths in a vector digital map.
Intelligent Speed Adaptation
Intelligent Speed Adaptation (ISA) is technology we are developing which helps a driver to keep to the speed limit.
We are developing two kinds of ISA for London which we hope to make available to drivers on a voluntary basis.
Advisory ISA
This system takes the speed limit and displays the information to the driver via a dashboard unit. It is similar to the functionality found in many commercial satellite navigation devices (Garmin, TomTom etc). Advisory ISA brings the speed limit into the cabin of the vehicle and means that the speed limit is always available to the driver. Advisory ISA systems can also alert the driver when they exceed the speed limit for a given road.
Voluntary ISA
This system helps the driver by making it difficult to accidently accelerate beyond the speed limit. The units are intended to be small enough to fit within an engine bay or in the foot-well of a vehicle without being noticed. The Voluntary ISA we are investigating does not have the ability to apply any form of braking and will not impact acceleration up to the speed limit.
It is important to note that at all times it remains the responsibility of the driver to comply with the speed limit.
Also, there is no requirement to have this equipment fitted to your vehicle and there are no plans to do this in the future. As the devices are voluntary, they can be deactivated at any time.
How it works
The key to both systems is that the vehicle is aware of its location on the road and the speed limit at that location. It does this using a Global Positioning System (GPS) signal and a digital speed limit map which is held within the ISA unit.
Note the devices do not store any information regarding location, time or any other variable, including driver speed over the length of a journey.
Download an image of the ISA speed map (PNG 1.2MB)
Benefits
ISA may have many benefits beyond the expected reduction in casualties. These include:
- Reduced possibility of speeding tickets
- Improved driver style and
- An associated reduction in CO2 and fuel costs
Next steps
A beta Advisory ISA system is now available for public download, including source code released under the GNU license. Only users who are comfortable testing software and realise that beta software may contain bugs and still require development should consider using this application. Furthermore you should be prepared for TfL to seek feedback on your experience with the application.
Please note that you will need your own TomTom satellite navigation device to trial the system. Our advisory ISA will warn you if you exceed the speed limit constantly for a period of 15 seconds.
Users should be aware that under no circumstances do we want to interfere with your satellite navigation instructions, so the advisory ISA system is processed secondary by the device. This may lead to a delay of a few seconds in some places to the correct speed limit being displayed.
If you are interested in trialling this system please register your interest.
Once you have registered and accepted the Terms and Conditions of using the test system, you will be able to access the files needed to install the application and the intructions for usage.
Voluntary ISAs will continue to be developed and further information on registering your interest for trials of this technology will be made available at a later date. We intend to make these units available for Transport for London vehicles first and then may extend the trial to buses and taxis.
For developers
Along with the source code of our application, we are making available Point of Interest (POI) files to allow developers to create applications for other common satellite navigation systems.
A Keyhole Markup Language (KML) version of the ISA map is also available which can be used in conjunction with Microsoft Live Maps or other GIS applications.
Please note we are unable to offer support to developers and these files are provided on an as-is basis.
