FOI release

GATSO Type 24+AUS speed device

19380 We have a received a request under the Freedom of Information Act 2000 for the following on 15 July 2011:  In a previous FOI request…


GATSO Type 24+AUS speed device (PDF file - 368kb)

Request an accessible format.
If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email Please tell us what format you need. It will help us if you say what assistive technology you use.



We have a received a request under the Freedom of Information Act 2000 for the following on 15 July 2011: 

1. In a previous FOI request it was stated that the secondary check marks were the responsibility of the manufacturer to lay correctly. As the manufacturer of the Gatso Type 24+AUS is in Holland, how is this responsibility exercised? If it can be proven that the marks are not separated at the stated distance (in this case 5 feet) but are treated as 5 feet for viewing and prosecution does this invalidate the secondary check requirement?
2. Where does the liability lie for the accuracy of the secondary check markings?
3. The annual calibration certificate states the timing between the two photographs is correct within toleration limits. What are the toleration limits?
4. The operator manual requires the oscillator in the timing mechanism, to be changed every 2 years. This suggests a susceptibility to error over time or obsolesence. Please provide the technical details and consequences of not replacing the oscillator at the specified intervals.
5. A condition applied by the Secretary of State for Type Approval was that Gatso 24+AUS was not permitted for use top measure speeds less than 30mph. What is the reason for this and what is the effect on measurements of 30 to 38 mph?
6 Have any other conditions been applied to this Type Approved device?
7. The police or Safety Camera Partnership operator viewer of the photographs is required to apply the secondary check and be satisfied any difference is within 10% of the radar reading. If the difference is exactly 10%, should that be counted as within or without the specified tolerance? Is it permissible for the viewer to guess or estimate a distance other than from secondary marks crossed, ie accumulated 5 feet spaces?  

We released the following information on  28 July 2011.

Q1. The manufacturer may appoint an agent to act on its behalf.  The UK agent for Gatsometer is Serco.  The Home Office does not specify the separation of the secondary marks.  Any marks at any known distance can be used. The secondary marks should be laid out in accordance with the manufacturer’s or agent’s instructions, but other methods (such as photogrammetry) may be used to establish a secondary speed. 
Q2. The manufacturer or agent is responsible for the installation of the system.
Q3. The tolerances are specified in section 7.10 of the Speedmeter Handbook, a copy of which is attached to this correspondence.
Q4. We have not been able to find this statement in the operators’ manual.  Section 4.5.5, however, mentions a battery on the real time clock that has a lifetime of about 2 years.
Q5. On very rare occasions and only when reporting speeds under 30 mph the system did not meet our requirements.  On these very rare occasions there will be a discrepancy between primary and secondary speeds well in excess of the 10% tolerance.  Because this discrepancy would invalidate the prosecution, the speed restriction is precautionary.   There is no risk to reported speeds greater than 26 mph.  Because the next valid speed limit is 30 mph, it was convenient to choose this speed as the boundary.
Q6. The only conditions for type approval are laid out in the type approval order, the type approval agreement and the schedule to the agreement.    Copies are attached to this correspondence.
Q7. A secondary speed measurement exactly 10% out from the primary speed measurement is outside of our stated tolerance, and the prosecution would not be pursued.  In practice, however, it is likely that expert advice would be sought to explain this unusually large discrepancy.  If an explanation was found, and another method of measuring the speed, e.g. photogrammetry, was within tolerance, a prosecution may be pursued.

The Speedmeter Handbook (Fourth Edition) by DR S R Lewis

Date: Fri Jul 29 10:18:53 BST 2011

In response to a Freedom of Information request about the secondary check by the GATSO type 24+AUS speed device.

Published 29 July 2011