Discussion
The J11-J12 roadworks on the M27 have the Yellow Gantries Of Doom with SPECS cameras in both directions. However, I'm a bit confused as to how they're doing it...
There are only 2 cameras on each gantry, covering 3 lanes. How does that work then? It also appears that on each gantry the left camera is aimed at lane 3, and the right camera at lane 1. What's all that about
Also, I remember reading on here somewhere that SPECS was not type-approved for multi-lane use, so if you entered a zone in one lane and exited it in another, any speed reading produced was inadmissible. Is this still correct, if it ever was?
There are only 2 cameras on each gantry, covering 3 lanes. How does that work then? It also appears that on each gantry the left camera is aimed at lane 3, and the right camera at lane 1. What's all that about

Also, I remember reading on here somewhere that SPECS was not type-approved for multi-lane use, so if you entered a zone in one lane and exited it in another, any speed reading produced was inadmissible. Is this still correct, if it ever was?
When consulting with the SPECS suppliers on the M25 Tender recently I did get into a dialogue with the SPECS chap. At the time, 4 months ago, SPECS weren't allowed to measure you between two different lanes, so if the scheme on the M27 has only 2 camera gantries then as long as you go under the cameras in different lanes then you should be ok.
They have the technology to measure across lanes so to speak but no DOT apprvoal YET.
The point about the cameras not covering all the lanes is that you don't know which cameras are live and which aren't as the majority of cars will toe the line the main body of traffic will adhere to the limit.
They have the technology to measure across lanes so to speak but no DOT apprvoal YET.
The point about the cameras not covering all the lanes is that you don't know which cameras are live and which aren't as the majority of cars will toe the line the main body of traffic will adhere to the limit.
The type approval for SVDD (the core of SPECS) states:
In a letter on the Cheshire Safety Camera Partnership (which is no longer at the URL I have and which a search of the site does not turn up), it was stated that a SPECs camera on the M6 was: "under the type approval issued by the Home Office, ... approved to monitor 'only one traffic lane – either immediately below or the neighbouring lane'." Note that 'or', not 'and'.
On that basis, two SPECS cameras on a single gantry can monitor only two lanes, not three. Additionally, they can only monitor either the lane under the camera or the adjacent lane ... so, if placed over the hard shoulder and lane one (typical), they can only monitor the hard shoulder and lane one, or the hard shoulder and lane two, or lane one and lane two.
Whether the lane monitored by a camera can be changed dynamically, or is allowed to be changed (by type approval), I don't know, but I would think it unlikely.
Clearly, if one wished to challenge a NOIP for speeding detected by SPECS, one would want to see both photographs and be informed which pair of cameras were used (if not obvious from the angle of the photographs) and see the 'order' which sets out (I imagine) which lanes will be monitored.
ETA: A Guide to Type-Approval Procedures for Automatic Distance/Time Speedmeters used for Road Traffic Law Enforcement in Great Britain by Dr SR Lewis states: "6.1.3 When image detectors are used, both shall be positioned to use the same angle of view to the same registration plate of vehicles passing the measurement datum points."
Which pretty much means that the pairs of cameras must monitor the same lane.
Streaky
Home Office said:
The Distance Over Time Speed Measuring Device Approval 1999
The Secretary of State, in exercise of the powers conferred on him by section 20(4) and (5) of the Road Traffic Offenders Act 1988 (a) (Speeding offences etc: admissibility of certain evidence) and having prescribed for the purposes of that section a device designed or adapted for recording a measurement of the speed of motor vehicles by means of unattended cameras capturing images of a vehicle at each of two pre-determined positions on the road and by recording the time at each position and calculating the average speed over that distance (b), hereby approves as from 1st April 1999 for the purpose of detection of offences specified in section 20(2)(a), (b), (c) or (d) the type of such device known as the Speed Violation Detection Deterrent (SVDD), manufactured by Symonds Group Ltd.
It is my highlighted text that is interpreted as meaning that only one lane can be monitored by one camera ... provided the pairs of cameras are set up covering the same lane (see below).The Secretary of State, in exercise of the powers conferred on him by section 20(4) and (5) of the Road Traffic Offenders Act 1988 (a) (Speeding offences etc: admissibility of certain evidence) and having prescribed for the purposes of that section a device designed or adapted for recording a measurement of the speed of motor vehicles by means of unattended cameras capturing images of a vehicle at each of two pre-determined positions on the road and by recording the time at each position and calculating the average speed over that distance (b), hereby approves as from 1st April 1999 for the purpose of detection of offences specified in section 20(2)(a), (b), (c) or (d) the type of such device known as the Speed Violation Detection Deterrent (SVDD), manufactured by Symonds Group Ltd.
In a letter on the Cheshire Safety Camera Partnership (which is no longer at the URL I have and which a search of the site does not turn up), it was stated that a SPECs camera on the M6 was: "under the type approval issued by the Home Office, ... approved to monitor 'only one traffic lane – either immediately below or the neighbouring lane'." Note that 'or', not 'and'.
On that basis, two SPECS cameras on a single gantry can monitor only two lanes, not three. Additionally, they can only monitor either the lane under the camera or the adjacent lane ... so, if placed over the hard shoulder and lane one (typical), they can only monitor the hard shoulder and lane one, or the hard shoulder and lane two, or lane one and lane two.
Whether the lane monitored by a camera can be changed dynamically, or is allowed to be changed (by type approval), I don't know, but I would think it unlikely.
Clearly, if one wished to challenge a NOIP for speeding detected by SPECS, one would want to see both photographs and be informed which pair of cameras were used (if not obvious from the angle of the photographs) and see the 'order' which sets out (I imagine) which lanes will be monitored.
ETA: A Guide to Type-Approval Procedures for Automatic Distance/Time Speedmeters used for Road Traffic Law Enforcement in Great Britain by Dr SR Lewis states: "6.1.3 When image detectors are used, both shall be positioned to use the same angle of view to the same registration plate of vehicles passing the measurement datum points."
Which pretty much means that the pairs of cameras must monitor the same lane.
Streaky
Edited by streaky on Thursday 24th January 18:49
streaky said:
The type approval for SVDD (the core of SPECS) states:
In a letter on the Cheshire Safety Camera Partnership (which is no longer at the URL I have and which a search of the site does not turn up), it was stated that a SPECs camera on the M6 was: "under the type approval issued by the Home Office, ... approved to monitor 'only one traffic lane – either immediately below or the neighbouring lane'." Note that 'or', not 'and'.
On that basis, two SPECS cameras on a single gantry can monitor only two lanes, not three. Additionally, they can only monitor either the lane under the camera or the adjacent lane ... so, if placed over the hard shoulder and lane one (typical), they can only monitor the hard shoulder and lane one, or the hard shoulder and lane two, or lane one and lane two.
Whether the lane monitored by a camera can be changed dynamically, or is allowed to be changed (by type approval), I don't know, but I would think it unlikely.
Clearly, if one wished to challenge a NOIP for speeding detected by SPECS, one would want to see both photographs and be informed which pair of cameras were used (if not obvious from the angle of the photographs) and see the 'order' which sets out (I imagine) which lanes will be monitored.
ETA: A Guide to Type-Approval Procedures for Automatic Distance/Time Speedmeters used for Road Traffic Law Enforcement in Great Britain by Dr SR Lewis states: "6.1.3 When image detectors are used, both shall be positioned to use the same angle of view to the same registration plate of vehicles passing the measurement datum points."
Which pretty much means that the pairs of cameras must monitor the same lane.
Streaky
Thanks for that.Home Office said:
The Distance Over Time Speed Measuring Device Approval 1999
The Secretary of State, in exercise of the powers conferred on him by section 20(4) and (5) of the Road Traffic Offenders Act 1988 (a) (Speeding offences etc: admissibility of certain evidence) and having prescribed for the purposes of that section a device designed or adapted for recording a measurement of the speed of motor vehicles by means of unattended cameras capturing images of a vehicle at each of two pre-determined positions on the road and by recording the time at each position and calculating the average speed over that distance (b), hereby approves as from 1st April 1999 for the purpose of detection of offences specified in section 20(2)(a), (b), (c) or (d) the type of such device known as the Speed Violation Detection Deterrent (SVDD), manufactured by Symonds Group Ltd.
It is my highlighted text that is interpreted as meaning that only one lane can be monitored by one camera ... provided the pairs of cameras are set up covering the same lane (see below).The Secretary of State, in exercise of the powers conferred on him by section 20(4) and (5) of the Road Traffic Offenders Act 1988 (a) (Speeding offences etc: admissibility of certain evidence) and having prescribed for the purposes of that section a device designed or adapted for recording a measurement of the speed of motor vehicles by means of unattended cameras capturing images of a vehicle at each of two pre-determined positions on the road and by recording the time at each position and calculating the average speed over that distance (b), hereby approves as from 1st April 1999 for the purpose of detection of offences specified in section 20(2)(a), (b), (c) or (d) the type of such device known as the Speed Violation Detection Deterrent (SVDD), manufactured by Symonds Group Ltd.
In a letter on the Cheshire Safety Camera Partnership (which is no longer at the URL I have and which a search of the site does not turn up), it was stated that a SPECs camera on the M6 was: "under the type approval issued by the Home Office, ... approved to monitor 'only one traffic lane – either immediately below or the neighbouring lane'." Note that 'or', not 'and'.
On that basis, two SPECS cameras on a single gantry can monitor only two lanes, not three. Additionally, they can only monitor either the lane under the camera or the adjacent lane ... so, if placed over the hard shoulder and lane one (typical), they can only monitor the hard shoulder and lane one, or the hard shoulder and lane two, or lane one and lane two.
Whether the lane monitored by a camera can be changed dynamically, or is allowed to be changed (by type approval), I don't know, but I would think it unlikely.
Clearly, if one wished to challenge a NOIP for speeding detected by SPECS, one would want to see both photographs and be informed which pair of cameras were used (if not obvious from the angle of the photographs) and see the 'order' which sets out (I imagine) which lanes will be monitored.
ETA: A Guide to Type-Approval Procedures for Automatic Distance/Time Speedmeters used for Road Traffic Law Enforcement in Great Britain by Dr SR Lewis states: "6.1.3 When image detectors are used, both shall be positioned to use the same angle of view to the same registration plate of vehicles passing the measurement datum points."
Which pretty much means that the pairs of cameras must monitor the same lane.
Streaky
Edited by streaky on Thursday 24th January 18:49
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