I have just copied this quote below from another thread made by Rallyman72. Does anybody know whether these guidelines are correct? If so are the reference points in my summons 'the end of the layby on nearside just after ***** bridge' and 'start of kerb on central reservation' questionable?
I can see a couple of problems but i'm not sure how the court would see it? Might just be pissing into the wind.
Firstly the incident is recorded at 20:08 on a day when the sunset at 20:03 (according to quick check on website) therefore I would assume that there would be no shadows to measure on an unlit road at dusk?
Secondly even if the above is not true the reference points are on separate sides of the road, one of which would not have been close to my vehicle (as I know that I travelled in the fast lane on this journey) and nor would I have cast a shadow on both of them (or them on me) unless the road did a full 180 (which it doesn't i'm glad to say).
I was caught using a VASCAR 'follow check' method with no video.
I am considering getting a friend who is a land surveyor to physically measure and record the distances between these two reference points as the distance doesnt seem be 100% when checked in my car. I would like to know how far away from the specified distance of 1.272 miles, the actual distance needs to be before casting doubts on the police officers recordings. I wouldn't want to waste his time in having to survey a mile and a quarter of dual carriageway.
I have just found out that according to the spec my vehicles top speed is 103mph. I am being prosecuted for 106.8 on a level section of road. I don't know what my top speed is but i'm not about to find out as I will be facing another summons. If the vehicle hasn't been modified can I just tell them that it won't go that fast? I can't test it unless I want to head to Silverstone?
Any thoughts?
QUOTE
QUOTE (ACPO)The detection of speeding offences using the equation: Speed = Distance/time is a long established practice. Initially this was carried out by the use of a certified stopwatch and the odometer of the patrol car. Whilst this principle remains, technology has allowed for the introduction of sophisticated equipment, which has proved to be far more efficient and accurate. The operation of the devices simply involves the operation of a distance switch and a time switch, in the appropriate sequence. This calls for a high level of operator accuracy and, in order to achieve it, a good deal of practical experience is required.
Where a vehicle is, in the opinion of a police officer, travelling at an excessive speed the device is used as corroboration.
The checking of a target vehicle's speed can be done by a number of methods.
In order that this can be done, the target vehicle must be checked between two reference points best defined as ‘either a permanent or temporary identifiable point on or near the carriageway’:
(a) Which either casts a shadow so as to strike a moving vehicle, or which is so placed that the shadow of a moving vehicle strikes it or its shadow; or
(b) Where there is physical contact between the road wheels of the moving vehicle and a reference point; e.g. change of surface, drain; or
© Where the target vehicle and the police vehicle are side by side.
There are five alternatives
• a moving shadow on a stationary object or a mark on the road surface;
• a moving object on a stationary shadow or a mark on the road surface;
• a shadow-to-shadow contact;
• physical contact of vehicle wheels with reference point;
• both vehicles are side by side;
By using reference points, which fit this definition, any uncertainty can be eliminated.
It is important to remember the police vehicle must pass between the same points as the target vehicle. This is essential as the distance information is taken from the police vehicle.
When the police vehicle has travelled between the two points and the distance switch operated, on at the first point and off at the second point, the device then knows the distance between the points. As the target vehicle travels between the same two points, the time switch is operated. The switch being switched on at the first point and off at the second point. The device now knows the time the target vehicle took to travel between the two points.
The device now has both parts of the equation required to calculate the target vehicle's average speed. This is done in a fraction of a second and the result is then visible on a digital display.
If for any reason the operator has any doubt as to the validity of the check, it must be abandoned.
11.3 Types of Check
11.3.1 Follow Check
This type of check is carried out when the police vehicle is following the target vehicle. As the target vehicle passes the first reference point, the time switch is turned on. As the police vehicle passes the same reference point, the distance switch is turned on. As the target vehicle passes the second reference point, the time switch is turned off.
The device now knows the time the target vehicle took to travel between the two reference points.
As the police vehicle passes the second reference point, the distance switch is turned off. The device now knows the distance between the two reference points that the target vehicle has travelled.
11.3.2 Pre-Fed Distance Check
This type of check is carried out when the police vehicle travels between the two reference points. Turning the distance switch on at the first point and off at the second point.
The police vehicle then parks in a position that the two reference points can be clearly seen by the operator.
The device has the distance between the reference points stored. As a target vehicle passes between the points the time switch is turned on and off. The device can then calculate the speed. Providing the distance information is not cleared from the device the police vehicle can remain parked and, by clearing the time information only, another target vehicle can be checked.
11.3.3 Being Followed Check
This check is carried out when the police vehicle is travelling in front of the target vehicle that is approaching from behind at a speed, which is excessive.
The police vehicle will travel between the two reference points, with the operator turning the distance switch on and off. The device now knows the distance travelled.
As the target vehicle, still approaching from the rear, passes the same points the time switch is turned on and off. The device now knows the time taken to travel between the reference points. The device knows the distance and time and can calculate the speed. NB When using this method operators should guard against any suggestion of provoking another driver to commit the offence especially if the police vehicle is unmarked.
11.3.4 Crossing Check
This check is started when the police vehicle is stationary.
As the target vehicle passes the first reference point, the time switch is operated. The police vehicle then moves off behind the target vehicle, operating the distance switch as the police vehicle passes the same reference point.
With the police vehicle now following the target vehicle and both time and distance switched on, the completion of the check is the same as the ‘follow check’.
11.3.5 Dial in Distance Check
This mode enables a known distance previously measured by the device to be fed into the device computer without the need to drive again over the route. Simply record the distance on the same push button switches as used for calibration purposes. This procedure can also be used with the control module removed from the car and plugged into the portable battery pack.
Particular care must be exercised where shadows are used as these will change with the movement of the sun
The minimum distance for any check is generally 1/8 or .125 of a mile. However checks over a shorter distance, down to an absolute minimum of 0.07 of a mile, are permissible under the following circumstances:
(a) This minimum distance is only for Pre-fed or Dial in Distance Checks.
(b) The reference points at both the start and end of the check are physical features on the road surface, which provide a clear and visual contact (e.g. white line/change of surface) not shadows.
© The maximum speed limit at the site does not exceed 40mph.
Trainers are to be satisfied that operators carrying out reduced distance checks are capable of performing the function professionally
11.4 Calibration
In order to maintain accuracy these devices must be calibrated in accordance with the manufacturer's instructions. Full calibration must be carried out:
(a.) on initial installation,
(b.) following removal and reinstatement,
(c.) following the fitment of new tyres, and
(d.) in any case at weekly intervals.
In order to establish the ongoing accuracy of the device a check must be carried out at the commencement of each tour of duty and at the end of that tour of duty if it has been used to detect an offence.
If the device is found to be inaccurate, then not only must the defect be remedied but also any offences detected since the previous accuracy check should be reviewed, as it is not known at what point the equipment became defective.