FOI release

Speedmeter Type Approval

FOI 5730 We have a received a request under the Freedom of Information Act 2000 for the following: “Re: Freedom of Information enquiry about…

Documents

Detail

FOI 5730

We have a received a request under the Freedom of Information Act 2000 for the following:
“Re: Freedom of Information enquiry about the performance of the LTI 20-20 handheld laser speed guns.

With respect to this Freedom of Information enquiry about the performance reliability of the LTI 20-20 laser speed gun, I refer you to your Freedom of Information reply of 10 January 2006, Reference: T45896/5, a transcript of which is included below.

This stated that, “A laser speedmeter works by measuring the change of distance to the target. It cannot distinguish between changes due to the movement of the target and changes due to the operator deliberately moving the laser and target position so as to induce constant decrements of the distance to it.”

The letter also stated, “it (the LTI 20-20) cannot detect when the operator deliberately moves the laser with the intent of generating a false reading.”

Under the Freedom of Information Act 2000 I ask you to provide answers to the following questions;

Do LTI 20-20 laser speed guns include any means by which they are able to distinguish between, “the operator deliberately moving the laser beam relative to the target so as to induce constant decrements of the distance to it” and “the operator inadvertently or accidentally moving the laser position relative to the target so as to induce constant decrements of the distance to it”.

If the LTI 20-20 is able to distinguish between the two situations described in question (1), what are the principles of the method by which the LTI 20-20 laser speed gun is able to achieve this.

What tests, measurements and/or analysis have been carried out by or on behalf of the Home Office with LTI 20-20 laser speed guns to determine the acceptable amount that the laser beam can move, relative to the target, during the speed acquisition period, before there is a reasonable possibility of this causing inaccurate, or unreliable, speed measurements. What were the findings of such tests, measurements and/or analysis and what is the amount of movement of the laser relative to the target that is likely to cause such errors, with respect to the permitted variation of measuring distance.

What numerical standards are specified for the permitted amount of movement of the laser beam of the LTI 20-20 laser speed gun relative to the target during the speed acquisition period, with respect to the permitted range of measuring distances.

What tests have been carried out by or on behalf of the Home Office to measure the amount of movement of the laser beam on a target that is likely to occur, during the speed acquisition period, when a handheld LTI 20-20 laser speed is used by a typical operator. What were the results of such tests.”