§ Mr. SwayneTo ask the Secretary of State for the Home Department (1) to what extent the VASCAR vehicle speed detection device relies on human inputs. [52443]
134W(2) if he will make a statement about the accuracy of the VASCAR vehicle speed detection device. [52444]
§ Mr. DenhamThe VASCAR vehicle speed detection device relies in part on the operator accurately and consistently operating switches. These start and stop a clock and, where necessary, a distance measurement from the vehicle's odometer. The instrument can, alternatively, be pre-fed with the distance between two selected marker points.
Guidance from the Association of Chief Police Officers (ACPO) requires operators to be trained and to pass a test as to their performance. They must demonstrate in a sequence of five measurements that none has an error greater than two miles per hour and that the average error across all five is less than 0.75 miles per hour. They are also trained on the selection, for pre-fed operation, of road marks, in order to minimise parallax errors.
VASCAR also relies on frequent distance calibration checks. ACPO guidance requires these to be carried out at the start and, where VASCAR has been used, at the end of shifts. There are minimum distances over which measurements are made. The clock in the device is crystal controlled and its errors are insignificant.
Where the operator is fully trained and the ACPO guidance followed, I am satisfied that the VASCAR device is accurate.