Speed Traps 101

ALL YOU EVER WANTED TO KNOW ABOUT SPEED TRAPS – BUT WERE AFRAID TO ASK

(Part One)

Late last year I got flashed by a speed camera as I made the downhill run into the Wilderness from Cape Town on the N2 – You know the section – its where they have the very confusing multiple speed limits, each applicable to an individual traffic lane on the same road, and the absolutely baffling signage which optimistically attempts to indicate which speed limit is applicable to which lane. And two weeks ago I received the invitation to part with an absurd sum of money “before due date” or else have to explain to a magistrate why I was doing 62 km/h in a 40 k m/h zone. This annoyed me to the extent that I decided to write to the prosecuting authority and express my contempt at the absurdity of the speed limit configuration and accompanying signage on that section of the N2, and vainly hope that the charge would be dropped. It then occurred to me to dig into just what process traffic authorities have to follow in setting up unattended speed traps and successfully prosecuting offenders.

But where to start digging? The local law enforcement agency was understandably but extremely unhelpful, which led me to ask myself if any-one, any-where in the country had successfully defended a charge of speeding in court and if so, on what grounds. A short visit to a friendly law-library hit the jackpot – I found an absolute gem of a decided case referenced “State v Snyman 2001 (1) SACR 354 (N)” in which an alleged speedster, convicted and sentenced by a magistrate, had taken his case to the High Court, on the grounds inter alia that the traffic inspector had failed to set up and operate his speed measuring equipment in accordance with certain “guidelines”, and had both the conviction and sentence set aside. The following quote from the written judgement by Justice AJ Penzorn, with Justice JP Tshabalala concurring, says it all:

What we then have before us in summary is the following situation. A specific device is used to test speed. The prosecuting authorities in conjunction with the various role players involved in the prosecution of speeding offences using particular devices as well as authorities concerned with the accuracy of such devices have laid down certain guidelines to ensure that the use of such devices can be relied upon:

Whether or not compliance with those guidelines will indeed remove any reasonable doubt as to the accuracy of speed measurements taken I need not express a view on. However, it seems to me that if the prosecuting authorities do not comply with their own standards by which they seek to ensure that speed are measured accurately, then there must perforce be a doubt as to the accuracy of measurements which are then obtained…..

…In all these circumstances it seems to me that a doubt exists as to the accuracy of the equipment used on this particular day and for this reason I would allow the appeal and set aside the conviction and sentence.

Now, knowing what to look for and deciding to look at all types of speed trapping, a little further research brought three very interesting sets of “rules” or “guidelines” to light, namely:

“General Guidelines for Prosecution with regard to Speed Measurements”, prepared by The Working Group on Speed Measuring Equipment;

“General Guidelines for Prosecution with regard to Speed Measurements”, January 2002, prepared by The Technical Committee for Standards and Procedures for Traffic Control and Traffic Control Equipment; and, Section 29 of the National Prosecuting Authority’s “Policy Manual to all public Prosecutors”, containing guidelines and procedures for traffic prosecutions.

The briefest of these is the last, the Section 29 directives to local and provincial traffic authorities, and it may be worthwhile quoting these in full as they have profound implications for a successful prosecution for speeding, even before the correct use, by traffic officials, of their speed measuring equipment is brought into question.

Part 29: Traffic Prosecutions:

Guidelines issued by the Technical Committee for Standards and Procedures for Traffic Control. Equipment should be complied with in all areas of jurisdiction, subject to paragraphs 2 and 3 below.

In the prosecution of speeding offences, a DPP (Director of Public Prosecutions) may decline to authorise the use of radar equipment if, in his or her opinion, its use is rendered problematic by the road or other conditions.

If there is no expert witness available to testify about a particular device and to deal with the challenges raised with regard to its operation, the DPP may suspend or cancel authorisation for the use of such a device.

The following general rules apply in respect of speeding offences:

(a) When using equipment involving the use of cables placed across the roadway and linked to the measuring device, two independent devices must be used. Similarly, two separate sets of cables are required and no "y" pieces may be used.

(b) The readings on the two independent devices may not differ by more than 3%. If the difference is greater than that, the charge must be withdrawn. When the readings differ by less than 3%, the accused must be prosecuted for the lower of the two readings.

(c) A margin of 10 km/h must be allowed in all cases before a prosecution is instituted to allow the driver a small margin of error.

(d) Subject to paragraph (f) below, traffic officers should allow the person who has been trapped to inspect the trapping device and to observe the readings displayed.

(e) The traffic authorities must be instructed to make notes concerning additional details about what occurred during the incident on the back of their copy of the summons to enable them to comprehensively give evidence later.

(f) Where the accused is not stopped and informed of the commission of the offence immediately, notice thereof must be issued no later than 30 calendar days thereafter.

(g) Where cameras are used, clear notice of such a fact must be given to users of the road in question.

(h) Prosecutors must inform their local authorities that cases will be withdrawn if traffic officers fail to attend the court on the first date of trial. In deserving cases eg. illness, the matter may be postponed once. (Absence on account of leave is generally not acceptable and the case should be withdrawn.)

(i) These directives should be brought to the attention of the local or provincial traffic authorities.

Note particularly paragraph (f), where the alleged speeding vehicle is not stopped (i.e. unmanned traps etc.) the traffic authorities are required to inform the “accused” of the commission of the offence within 30 calendar days. This they generally do by posting to the registered owner of the vehicle (who is legally presumed to be the “accused” unless he or she can show that he/she was not driving) a “Notice Of Intention To Prosecute”. The traffic authority must pass that notice to the Post Office for delivery, by ordinary postage, within thirty calendar days of the offence. When you receive that notice, check that the date of the alleged offence is within thirty calendar days of the date of issue of the notice, which must appear on the notice. Also check that the date on the postmark on the envelope in which the notice was posted is within thirty days of the alleged commission of the offence. If either or both periods exceeds thirty calendar days, get on the phone to the prosecutor dealing with traffic offences in the magisterial district in which the alleged offence occurred and invite him to withdraw the charge unconditionally on the grounds of unreasonable delay in advising you of the charge and also as required by the National Director of Public Prosecutions. If the prosecutor agrees, get the withdrawal in writing, if not, go to court with the notice and envelope and ask the magistrate to throw the case out before pleading to the charge.

If you absolutely have to go to court, and the traffic officer who issued the Notice Of Intention To Prosecute, in the case of an unattended speed trap, or the traffic officer who “caught” and photographed you, in circumstances where you were not stopped, is not in court, remind the prosecutor of paragraph (h) of the Director Of Public Prosecution’s directives and unless he can convince you (and the magistrate) that the officer’s failure to attend is a result of illness (which must be attested to by the presentation of a medical certificate) he (the prosecutor) is obliged to withdraw the charge. I have seen experienced prosecutors break down and make choking, strangled noises when confronted with this one – they do tend to argue about it however – this means that you may have to ask the court to insist on either the medical certificate or request the dismissal of the charges. And don’t let the prosecutor get away with requesting that the court postpone the case if the officer is not present – the Director of Public Prosecutions has instructed that the officer be in court “on the first date of trial”

Also give paragraph (a) of the Director Of Public Prosecution’s directives a good read– if the device that nabbed you relies on cables across the road, there must be two absolutely independent devices, which must show two independent readings, and the higher reading must be within 3% of the lower reading. (e.g. if the lower reading is 100 km/h, the higher reading must be not more than 103 km/h. Further, the lower reading must not be more than 10 km/h greater than the posted speed limit. The “General Guidelines for Prosecution with regard to Speed Measurements”, January 2002, prepared by The Technical Committee for Standards and Procedures for Traffic Control and Traffic Control Equipment deal with critical technical aspects of setting up and operating different types of speed measuring equipment such as radar, laser, sensor lines, etc. and contain the gritty reasons for the setting aside of the conviction and sentence of the accused in the “State v Snyman” case. Both the Working Group’s and the Technical Committee’s guidelines are somewhat lengthy, albeit very similar. So if an interest is expressed and with your Editor’s blessing I’ll save them for a future insertion in your magazine. But to whet appetites, and by way of example, did you know that the radar or laser equipment must be mounted on a tripod which must stand on a “firm and stable surface” and may not, under any circumstances, be mounted in or on a vehicle? This means that if the cop zaps you from within the comfort of his parked patrol car with the instrument on the dash – he is going to look foolish in court. Oh, and by the way – I got my invitation to pay for doing 62 km/h in a 40 km/h zone on the N2 in the post more than thirty days after the event – the prosecutor saw the light and the charge was unconditionally withdrawn.

(Part Two)

General Principles

In last month’s issue of the magazine we saw that the National Prosecuting Authority had instructed that, with two provisos, the Guidelines issued by the Technical Committee for Standards and Procedures for Traffic Control and Traffic Control Equipment should be complied with (by traffic and prosecuting authorities) in all areas of jurisdiction. We also saw that the High Court, [State v Snyman 2001 (1) SACR 354 (N)] had found “…that if the prosecuting authorities do not comply with their own standards by which they seek to ensure that speed are measured accurately, then there must perforce be a doubt as to the accuracy of measurements which are then obtained “ This means that there is legal precedent for the view that the traffic and prosecuting authorities are compelled to adhere to the Technical Committee’s guidelines for a prosecution to succeed. The National Prosecuting Authority’s instructions, taken with the High Court’s decision implies that traffic authorities conducting speed traps have no discretion, they simply must abide by the guidelines. If they don’t, they do not have grounds for prosecuting road users “caught” in speed traps. (This is not to say that you will always get away with speeding on technical grounds – if the officer or prosecutor is wise you will be charged with several alternatives, such as reckless or negligent driving, where the officer’s eye-witness account of your driving behaviour is more likely to impress the magistrate – but that’s another matter)

Before getting into the technical detail of what traffic officers must do in setting up and operation a speed trap, it is as well to examine the general rules established by the Technical Committee with regard to speed measurements, these are:

GENERAL GUIDELINES FOR PROSECUTION WITH REGARD TO SPEED MEASUREMENTS

1. That the state only proceeds with prosecution when all the guidelines for prosecution of specific speed measuring equipment are complied with.

2. That the operator attended a general course on speed measurement.

3. That the operator is in possession of an operator’s certificate for the specific type of SME (Speed Measuring Equipment).

4. That the manufacturer’s operating instructions are followed, unless the National Director of Public Prosecutions’ prosecuting guidelines are more stringent.

5. That an approved or accredited laboratory tests and/or calibrates:

* All speed measuring equipment

* All distance measuring equipment

at least once every six months and issues a calibration certificate.


5.1 All distance checking markers for validation of SME’s shall be checked and/or validated using calibrated distance measuring equipment and a certificate shall be obtained by the relevant traffic authority at least once every six months.

6. That no speed measurement may be implemented within 300 metres of the commencement of the speed limit zone except with permission from the Director of Public Prosecutions.

7. That maintenance and repair of equipment and accessories may only be attended to by the manufacturer, distributor, or his appointed agent, and the equipment must be recalibrated thereafter.

8. All results required to be recorded shall be recorded in an appropriate register.

Of interest here is that the operator of the speed trap must have attended a general course on speed measurement. The guidelines do not require that the operator must have been evaluated and/or passed an examination on speed measurement, but merely that attendance at an appropriate course is necessary. In addition, the operator need not have proof of his or her attendance of such a general course available at the site of the speed trap, but, since it is a requirement that such a course must have been attended, it is implicit that the accused may demand proof of such attendance. Therefore, in preparing to challenge the charge it is desirable that the accused (or his or her attorney) demand that the traffic authority provide such proof, in a manner that will satisfy the court, that an appropriate course was indeed attended. Although not a specific requirement of the guidelines it may also be desirable to ascertain whether or not a test, examination or other evaluation was a part of the course and if so, how the particular operator performed in that evaluation. If he did poorly, or if there was no evaluation, there may be grounds to challenge the operator’s general competence if/when the matter goes to court.

In addition to having attended a general course on speed measurement, the operator of speed measuring equipment must also have received training on the specific equipment (e.g. the make and model of the specific radar, laser or other SME), which is in use at the speed trap. In terms of other requirements (which will be addressed in a future article) proof of such training, in the form of an operator’s certificate must be available at the site of the speed trap. When stopped at a speed trap you may demand to see that certificate. It is debatable whether it is the original or a copy of the certificate that must be available at the site of the speed trap. My opinion is that, if it may be a copy, it must at least be a copy certified (by a commissioner of oaths) to be a true and exact copy of the original. If the operator’s certificate is not available at the site of the speed trap that absence may form a technical defence against a charge of speeding. If the operator does produce his or her operator’s certificate (on demand) it would be in your interests to confirm that the specific speed measuring equipment actually used in the speed trap (e.g. type, make and model) exactly match the description of the equipment which the operator is deemed competent to operate in terms of his or her operator’s certificate. In this regard, and if there is any doubt, take the time to write down the type, make, model and serial number(s) of the equipment used as well as the description of the equipment in respect of which the operator is competent as reflected on the operator’s certificate, and if possible use your cell-phone’s built-in camera to photograph both the operator’s certificate shown to you and the manufacturer’s identifying marks on the equipment. If there are two or more officers manning the speed trap, also confirm which one was actually operating the equipment at the time in question and make sure that any operator’s certificate proffered is that of the actual operator and not that of an on-looker. This sort of evidence may prove to be vital to your case if/when it goes to court.

The traffic authorities are required to have all equipment used in speed traps calibrated or tested at least every six months. Certificates attesting to that calibration must also be available for your inspection, on demand, at the site of the speed trap. Again make sure that the certificates apply to the actual individual equipments used (type, make, model, serial number{s} etc.) and document any possible discrepancies. Also note whether the certificate is the original, a certified copy or merely a photostat.

The injunction that speed trapping is only to commence at a distance of 300 metres (or more) from the start of the applicable speed zone is to allow the road user reasonable time and distance to slow down after becoming aware of the speed zone. I have known of instances where speed traps are set up within a few metres of the first sign advising of the commencement of a speed zone. (an example which comes to mind is the occasional speed trap at the end of the blue route or M3, where it terminates at a T-intersection with
Steenberg Road
, below Silvermine). If stopped at a speed trap it is therefore advisable to ascertain where the trap is in relation to the commencement of the speed zone and if the distance is too short, to thoroughly document the fact for possible evidence in court later.

Steenberg Road
, below Silvermine). If stopped at a speed trap it is therefore advisable to ascertain where the trap is in relation to the commencement of the speed zone and if the distance is too short, to thoroughly document the fact for possible evidence in court later.

If any incongruity is found relating to any of the certificates shown to you, or in the distance after commencement of the speed zone, you should bring your concerns to the immediate attention of the senior officer at the speed trap. If the senior officer then decides to proceed with the issue of a summons or other warrant you should request that your concerns be noted and signed, by that officer, on the back of both the officer’s copy as well as your copy of the summons or other warrant. If that officer refuses, note the fact as well as the officer’s name (its good to have a witness to this, but if no witness is available, get out the cell-phone camera so the officer may be identified later) and bring it to the attention of the court.

Next month we may have a look at the specifics of speed trapping using radar equipment – until then, remember that if you keep within the speed limits you will be mostly unlikely to need to read this. So as a preventative against boredom, stay under the limit.

To whet your appetite for next months article: Did you know that radar speed measuring equipment may NOT be used within 100 metres of a high tension cable or 100 metres of a neon or sodium street light within an angle of 45° of the front of the antenna? – that excludes most major urban arterials at night.

(Part Three)

Radar Speed Traps

This month we look at the procedures to be complied with by traffic authorities in setting up and operation speed traps using radar speed measuring equipment. The following procedures, quoted directly from the Technical Committee for Standards and Procedures for Traffic Control and Traffic Control Equipment’s guidelines, are required to be followed by traffic authorities in terms of both of Section 29 of the National Prosecuting Authority’s “Policy Manual to all Public Prosecutors” as well being implicit in a finding of the High Court [State v Snyman 2001 (1) SACR 354 (N)].

GUIDELINES FOR PROSECUTION WITH REGARD TO SPEED MEASUREMENTS BY RADAR EQUIPMENT

When selecting a site for a speed measurement exercise, the following must be adhered to:

Site selection must be done during daytime for day and night-time operation.

1.2 There shall be no large, stationary, or metal objects (e.g. patrol vehicle, bus shelter) within a radius of 50 metres in front of the radar SME.

1.3 There shall be no metal road signs or vertical flat surfaces within 15 (fifteen) degrees on either side of the aiming direction, within a distance of 200 metres of the antenna.

1.4 The equipment may only be used where there is a clear view, any obstruction taken into account, within 45 degrees of the direction of aim over a distance of 600 metres.

1.5 There shall be no high-tension cables within a radius of 100 metres of the antenna.

1.6 There shall be no discharge type lamps (e.g. sodium or neon) in operation within 45 degrees of the direction of aim within 100 metres of the antenna.

1.7 (a) * Equipment modified or permanently set that no signals are received and processed from vehicles more than 300 metres away may be used on straight roads. Vehicles used to test the modification are vehicles with a tare of not more than 750 kg.

* A copy of the certificate verifying the modification or setting has to accompany the equipment at all times.

(b) Equipment not modified as referred to in paragraph (a) shall only be used where rises and bends in the road take all vehicles out of the measuring area of the SME.


1.8 Ensure that the instrument’s tripod is standing on a firm and stable surface.

2. Setting up the Device

2.1 A copy of:

* a valid calibration certificate;

* the type approval certificate to SABS 1795-2, (applicable to equipment acquired after 31 July 1998); and

* the operator’s certificate, must be available at the site at all times.

2.2 Ensure that all digits on the display are functional.

2.3 Depress the test buttons and ensure that the readings obtained are as per the manufacturer’s specifications.

2.4 Verify operation using tuning fork method.

2.5 Check that the site is interference free by using a radar detector supplied by the supplier/manufacturer of the radar equipment.

3. Operation

3.1 Ensure that the radar is tested at the start and end of each speed measurement shift, using:

* the internal test feature;

* the tuning fork; and

* a radar detector to check site for interference.

3.2 The tests in paragraph 3.1 must be repeated every hour. Record the results.

3.3 Speed measurements with radar may only be taken when a radar antenna is mounted on a tripod, and not mounted in or on a vehicle.

3.4 If an unexplained spurious reading is observed, operation must be ceased immediately.

3.5 Ensure that no speed measurements are taken if any moving vehicle other than the measured vehicle is within 600 metres from the SME in the direction of operation. The driver shall be afforded the opportunity to view the speed reading when stopped.

It is unlikely that any knowledgeable traffic department, operating in an urban area such as Cape Town, would acquire or use radar speed trapping equipment for a number of reasons. These include:

It is implied in the National Prosecuting Authority’s “Policy Manual to all Public Prosecutors” (Paragraph 2) that the Director of Public Prosecutions should satisfy him or herself that the use of radar must NOT be “problematic in terms of road and other conditions and if not satisfied should “decline to authorise the use of radar equipment”;

Radar equipment may not be used if there is a high tension cable within 100 metres of the equipment;

Radar equipment may not be used if there are discharge type lamps within 100 metres and an arc of 45° on either side of the direction of aim of the antenna. Discharge type lamps include sodium or neon streetlights, neon advertising signs and the like. Such lamps emit electronic radiation that may be spuriously received and interpreted by the radar as a moving vehicle.

No reading may be taken if there is another moving vehicle within 600 metres of the direction of aim of the radar.

It is fairly obvious that factors such as these preclude the use of radar equipment in heavily trafficked urban areas with a proliferation of high tension cables, and lighting which discharges electronic impulses. Nevertheless, radar is popular with provincial traffic inspectorates operating in rural areas. Therefore, if trapped on the ‘open road’, it would be as well to examine the environment to ascertain that none of the mentioned factors that may give rise to false readings pertain. This applies particularly to Escom’s high‑tension transmission lines that often run parallel, or in close proximity, to the national routes. Should there be electric transmission lines within 100 metres of the speed trap, you should record the fact, ensure that it is brought to the attention of the senior officer at the trap (with the request that he note it on both his and your copy of any summons or other warrant) and, as mentioned in previous articles – use your cell-phone’s built‑in camera to record the position of the power lines in relation to the trap.

In setting up the speed trap the operator must conduct certain specified tests to ensure that the radar is operating properly. These tests must be carried out before speed trapping starts, at hourly intervals during the operation of the trap and at the conclusion of the trap. The results of these tests must be recorded in a register. You may request to see that register if stopped at a speed trap, and whether stopped or not (i.e. photographed and notified of an alleged offence at a later stage) you may demand that the traffic authority provide you with insight into the original register as well as a copy therefore (at your cost) to enable you to prepare a defence against the charge. This register is the traffic authority’s documentary ‘proof’ that the radar equipment used to trap you was in proper operating order. Therefore, if you were convinced that you were not speeding when trapped it would be advisable to consult an expert to look for anomalies in the recorded tests. Whether you were really speeding or not, the authorities’ failure to produce the register, would constitute a valid defence in court.

When stopped, look out for objects and surfaces as mentioned in paragraphs 1.2 and 1.3 of the guidelines applicable to the use of radar equipment quoted above. Note that a parked vehicle may have the same effect on the radar as “metal road signs or vertical flat surfaces” if it is within 15º on either side of the aiming direction and within a distance of 200 metres of the antenna.” The “vertical flat surface” need not be metallic – a wall or a rock face may also constitute such a surface and give rise to a spurious reading. Should you notice any such object or surface, again, note it, get the senior officer to record it and, most importantly, photograph it in relation to the speed trap and when given the opportunity, tell the magistrate about it.

If you were not stopped, but receive your summons later (preceded by the compulsory ‘Notice Of Intention To Prosecute’ within 30 days of the alleged offence) you may demand that the traffic authority identify the precise location of the speed trap so that it may be ascertained that there were no ‘proscribed’ objects within the radar’s range. If the traffic authority is unable to identify that exact location you may argue that a reasonable doubt exists.

In the quoted guidelines, critical distances in metres and angular measurements in degrees are frequently mentioned. If these distances or angular limitations are not complied with, there must be doubt about the accuracy of the speed measurement. This means that you should check these factors if at all possible and certainly attack the officer’s measurement thereof in court. For example, if there is a metal sign somewhere vaguely in the direction of aim of the radar and maybe within the mentioned distance – get the officer to explain to the court (under cross-examination) exactly how he measured the distance and angle, to prove beyond reasonable doubt that the guidelines were complied with and that no spurious reading was taken.

Attention has already been given (in last month’s article) to the importance of checking out the certificates that are required to be present at the site of the speed trap – When stopped, don’t forget to demand to see those certificates, and to examine them carefully for anomalies.

Paragraph 2.5 of the guidelines applicable to the use of radar speed measuring equipment requires that the operator “check that the site is interference free by using a radar detector supplied by the supplier/manufacturer of the radar equipment.” This is required to be done at the commencement and end of the speed-trapping shift and at hourly intervals during the operation of the speed trap. In order to do this however, it is obviously necessary that an appropriate radar detection device be present at the site of the speed trap. Although not directly specified, it is also obvious that any radar detection equipment used in terms of paragraph 2.5 must be in working order at the time of use and, if challenged, the prosecuting authorities must be able to prove that the detector was properly operational when used.

A particularly common failing on the part of traffic officers conducting speed trapping is that they tend to ignore paragraph 3.3 of the guidelines. This is so important that it is worth quoting the paragraph again:

Speed measurements with radar may only be taken when a radar antenna is mounted on a tripod, and not mounted in or on a vehicle.

Now how many times have you seen the local officers sitting in their Toyota Venture with the back flap open and the equipment mounted on a table in the vehicle? This is a definite “No-No” and if you are trapped under these circumstances – get the photograph, bring it to the attention of the prosecutor, and the charge will almost certainly be unconditionally withdrawn before it ever gets to court.

If, however, the officer was nearly doing it properly and the radar was not mounted “in or on a vehicle” check that the thing it is mounted on is a tripod, which itself is “standing on a firm and stable surface” - a camper’s table, chair, wooden crate etc. are not tripods – the equipment must be on a tripod. If there is no tripod – start photographing.

Next month we look at your nemesis – the laser speed measuring equipment.

(Part Four)

LASER Speed Traps

The most common form of manned speed trap you are likely to encounter in the Cape Town area is that utilizing laser SME (Speed Measuring Equipment.) This month we look at the procedures traffic authorities are required to follow in setting up and operating laser equipment, as determined by the Technical Committee for Standards and Procedures for Traffic Control and Traffic Control Equipment’s guidelines and required by Section 29 of the National Prosecuting Authority’s “Policy Manual to all Public Prosecutors” as well being implicit in a finding of the High Court [State v Snyman 2001 (1) SACR 354 (N)]. That finding of the High Court is particularly relevant in that the accuracy of laser equipment, when not operated in terms of the guidelines, was brought into question with the court finding “… that if the prosecuting authorities do not comply with their own standards by which they seek to ensure that speeds are measured accurately, then there must perforce be a doubt as to the accuracy of measurements which are then obtained…”

The specific “guidelines” in respect of Laser SME (Speed Measuring Equipment) are:

GUIDELINES FOR PROSECUTION WITH REGARD TO SPEED MEASUREMENTS BY LASER EQUIPMENT

Preparation

Prior to the machine being used for speed measurement, the following checks must be carried out and recorded:

A scope alignment test, vertical and horizontal, as detailed in the operator’
manual.

A fixed distance and zero velocity test:

The distance must be at least 100 metres and it must be a surveyed distance.

The distance error must not be more than + or ‑ 0,2 metres.

No speed-reading must be displayed when taking a measurement of a stationary object.

If any of the tests prove inaccurate the instrument must not be used.

A copy of:

A valid calibration certificate;

The type approval certificate to SABS 1795‑1, (applicable to equipment acquired after 31 July 1998); and The operator’s certificate, must be available at the site at all times.

Site Selection

When selecting a site for a speed measurement exercise the following must be adhered to:

The operator must have a clear uninterrupted view of the road and the vehicle measured for the duration of the measurement.

Identify a target suitable for scope alignment testing 200 metres away from the equipment.

A suitable distance marker must be selected to indicate the boundary of the measurement area. This distance shall not exceed 400 metres and need not be measured with a tape measure, but may be paced out or measured with the distance display feature of the laser. This is important as a positive vehicle identification must be made.

Ensure that the instrument’s tripod is standing on a firm and stable surface.

Setting up the Device

The SME shall at all times whilst being operated, be mounted on a tripod on a firm and stable surface and not be mounted in or on a vehicle.

Ensure that all digits on the display are functional.

Operation

The following must be adhered to whilst operating the equipment.

Verify correct operation using the self-test function.

Perform the scope alignment test, vertical and horizontal, before commencing with the speed measuring shift.

The tests in paragraphs 4.1 and 4.2 must be repeated every hour. Record the results.

For approaching vehicles, readings must be taken by aiming at the vehicle’s registration plate or the area between the head lamps (or if it is a motorcycle, its headlamp), ensuring that no panning takes place.

For receding vehicles, readings must be taken by aiming at the vehicle’s registration plate or the area between the vehicle’s rear lamps.

Ensure that you have:

a clear and uninterrupted view of the whole vehicle measured; and that no measurement is locked beyond 400 metres.

When viewed from the SME there must be a clear, visible separation between the vehicle target and any other visible vehicle.

The driver shall be afforded the opportunity to view the speed reading when stopped

Scope Alignment Test

Paragraph 1.1 of the guidelines requires that a “scope alignment test” be carried out before the equipment is used for speed measuring, while paragraph 4.2 , read with paragraph 4.3 requires that the tests be repeated every hour during the duration of any speed trap. Although the guidelines do not specifically require it, common sense dictates that the test also be conducted at the end of the speed trapping exercise to ensure that each and every speed reading taken for which a charge may be laid is bracketed by tests indicating that the laser equipment’s sighting scope was in alignment with the emitted laser beam by means of which the speeds were deduced. The results of the scope alignment tests are to be recorded in a “register”. Paragraph 1.3 implies that should the equipment, at any time fail to meet the scope alignment test it may no longer be used as a legal speed measurement device. Also note that in terms of paragraph 7 of the “general guidelines” (discussed in Part 2 of this series of articles), the operator or traffic official may not attempt to re-adjust the equipment in the event of its failing a scope alignment test – this must be carried out by the “…manufacturer, distributor, or his appointed agent, and the equipment must be recalibrated thereafter”

The reason for the scope alignment test is that the laser beam from which the speed of a vehicle is calculated is invisible to the naked eye and has a very narrow beam width. The Laser SME must therefore have a means - such as a sighting scope - to enable the operator to direct the laser beam onto a specific target vehicle. If the emitted laser beam and the target-sighting are misaligned, the operator could be sighting one vehicle while the laser beam is being directed to another nearby vehicle… and the misalignment need not be large for it to be significant. This is illustrated in the following diagram.

Paragraph 2.3 of the guidelines applicable to laser equipment determines that the “boundary of the measurement area should not be more than approximately 400 metres. The diagram shows that at 400 metres a misalignment of the sighting scope and the laser emitter of about ½º (half a degree) would be sufficient for the targeting scope to be focussed on the motorcycle, while the device is reading the speed of the car. (that is, given certain assumptions regarding lane width, distance of the device from the road edge and position of the vehicles in the lanes) Another assumption is that the targeting scope is focussed on the motorcycle’s headlamp while the laser is “hitting” the centre-line of the car.

It is apparent from the diagram that if the laser was picking up a point on the car closer to the motorcycle, the angle of misalignment may be smaller than half a degree. From this example it is clear that absolute alignment of the sighting scope and the laser emitter is critical for an accurate speed measurement if more than one vehicle is approaching (or receding from) the speed trap and hence it is vital that scope alignment tests be carried out before, after and at hourly intervals during the period of the speed trap’s operation.

If you intend defending yourself against a charge of speeding it is therefore essential that you demand a copy of the register wherein the carrying out of the mandatory scope alignment tests are recorded as well as a copy of the operator’s manual and examine that register thoroughly for anomalies. It will also be necessary for either yourself or your attorney to closely cross-examine the person who operated the equipment on the day to ensure that the operator is properly trained in carrying out the tests “as detailed in the operator’s manual” and that the tests were, in fact, conducted properly.

Fixed Distance And Zero Velocity Test:

This test, which the operator is required to carry out before the commencement of a speed trapping exercise is to ensure that the laser SME is accurately measuring distance and is not reading a speed from a stationary object.

The test entails the taking of a reading to a fixed object at a distance of more than 100 metres (but presumably less than 400 metres) where the distance has been accurately measured by a means independent of the laser’s own distance measuring function. The term used in the guidelines is “it must be a surveyed distance”. An argument may be made that the term “surveyed distance“ means that the distance must have been measured by a registered land surveyor or a properly trained survey technician… and it would certainly be worth your while to pursue this argument in court. (There is legislation and regulation governing “land surveys” and should your attorney be aware of this he or she would be well equipped to argue the matter) If the distance was not measured by an appropriately trained professional or technician, but, when measured by a traffic officer, the term must, at the very least, mean that a proper steel tape measure capable of measuring the distance in one measurement was used and that the length of the tape was such that the distance could be measured in one measurement. If anything other than a steel survey tape (which does not stretch or contract) was used or if the distance was more than the length of the tape, implying multiple measurement and addition of the component parts then doubt must exist as to the accuracy of the measurement and this doubt should be expressed in court.

This is illustrated in the diagram assuming measurements using a 30m tape. If the alignment of the tape deviates as little as 1.25º from the actual line (e.g. A-B and X1-B) on each of the first two measurements (or 650mm) the actual distance of 100m (A to B) could be measured as 100,023 metres. (A – X1 – X2 – X3 – B) Should the laser distance test then coincide with this false measurement it will appear to be within the acceptable bounds and consequently give rise to a false distance test which will have consequences for the accuracy of the speed measurements. It is for this reason that, if a traffic officer, in‑experienced in survey, conducts the measurement, a tape long enough to measure the distance in a single measurement is necessary. Accurate measurement over a chain of measures is a skilled operation requiring specialist survey equipment. It is highly unlikely that such equipment would be available at a speed trap.

Another aspect of the term “surveyed distance“ is that, if the prosecution claims that it was indeed properly surveyed by a appropriately competent person before the event, then the traffic authorities must be able to prove this by showing you (and the court) the survey peg over which the laser SME was mounted as well as the target object. You could explore this aspect yourself i.e. ask the prosecutor

and/or traffic authority for appropriate proof and/or demonstration before going to court or ensure that your attorney is aware of the aspect when going to court. If it is claimed that the distance was measured by a land surveyor or registered survey technician then demand an appropriate survey certificate attesting to the fact

The results of the Fixed Distance and Zero Velocity test must be recorded in a register which must be made available to you. However, there is nothing to prevent you from politely requesting that the officer conducting the speed trap (operating the laser SME) to repeat the test in your presence if/when stopped. At the same time you may enquire how the distance to the static target was surveyed. (Also ask to be shown any survey pegs) If the officers have done their job properly you may weaken your case, but if not, or if you are faced with refusal – the court needs to know that you expressed doubt at the time of the event and requested information which was either unsatisfactorily supplied or that you were refused

Certificates

Read paragraph 1.4 of the guidelines again to make sure that you know what certificates must (at all times) be available at the site of the speed trap. (Better yet keep a copy of the magazine on your person and refer to it when busted) You may ask to see these certificates and need to look at them carefully. Make sure the certificates apply to the specific equipment being used and check that the operator’s certificate proffered applies to the officer actually operating the device and not to an onlooker. If any anomalies are discovered, photograph the certificates and the equipment – make notes of the equipment’s serial numbers and the officer’s names – in fact record everything that may be of use to your attorney in court.

Mounting of the Equipment

Read paragraphs 2.4 and 3.1 of the guidelines applicable to laser equipment. Note that the instrument must be mounted on a tripod which itself stands on “a firm and stable surface” Note also that the SME may, under no circumstances – not at all – never – be mounted in or on a vehicle. If the equipment which nailed you is not on a tripod (never-mind sitting on a wooden crate in the back of a Toyota Venture) take as many photographs of the mounting as you can. A very common sight at speed traps conducted by Cape Town’s finest is that of the officer comfortably seated behind his laser in the back of the Venture. (Here an appeal to readers – if you see this sight anywhere, would you please, - without getting arrested – get the photographs and pass them on to me: That sort of photograph, with the time, date and place noted, would be invaluable in assisting other members to avoid paying the heavy fines) Should the equipment used in the trap which stops you not be tripod-mounted and you have the proof… let the prosecutor know ASAP that you intend defending the charge unless it is immediately and unconditionally withdrawn. When speaking to the prosecutor, gently refer him/her to the mentioned High Court case [State v Snyman 2001 (1) SACR 354 (N)]. You may be amazed at the rate at which the thing is dropped.


Panning

There are very good reasons for the admonition contained in paragraph 4.4 of the guidelines for the operator of the equipment to ensure that “that no panning takes place”. Panning is essentially moving the laser through an arc while the speed measurement is being taken, in much the same manner in which one would move a video camera through an arc whilst filming. However, unlike as with filming, panning while pressing the trigger of the laser speed measuring equipment can have a profound effect, creating a grossly misleading or inaccurate reading. This is because of the manner in which the system works. The equipment emits a series of separate, discrete laser pulses at known time intervals (about 40 pulses in 0.3 seconds). Each laser pulse is reflected off the target and that reflection received by the instrument. Since the speed of light is known, the period of time between the emission of a pulse and the detection of its reflection can be used to calculate the distance from the instrument to the target with a high degree of accuracy. If the target is moving, the emission and reception of the second (and subsequent) pulses will result in differing distance measurements and given that the period between pulses is known, the velocity of the target can be calculated. For example, if the target is moving directly towards the laser at a speed of 120 KmH and the laser operates for 0.3 seconds the distance differential measured by successive laser pulses (at 40 pulses in 0,3 seconds) will be about 250 millimetres.

(120 KmH = ±33.33 metres/second = 10 meters in 0.3 second = 0.25m in 1/40 of 0.3 seconds)

The effect of “panning” can now be illustrated as in the following diagram. Assume that the line A‑C represents a brick wall, 400m long (distance A‑C = 400 metres) and that a laser speed measuring equipment is set up at point X, 6.4 metres from the wall. (Distance X‑C). These distances represent the maximum distance at which a laser speed trap should operate and an estimated offset from the centreline of the road.

Now assume that the laser operator aims the instrument at point A on the wall and presses the trigger and, while the measurement is being taken swings or pans the instrument through the angle shown as ß on the diagram so that the instrument is aiming at point B at the end of the 0.3 second measuring period. The laser pulses would theoretically measure distances ranging from 400.051 m to 390.053 m in respect of the first and last pulses. A simple calculation would indicate that point B is about 10 metres closer to the instrument at point X than it is at point A. That is, in the 0.3 seconds it took to take the reading it would appear that the wall has moved about 10 metres closer to the instrument, which means that it would appear as if the wall was moving at a speed of about 120 KmH (119.98KmH). Given the assumptions, the arc through which the instrument is traversed or panned to give this spurious reading is incredibly small – about two one‑hundredths of a degree (0.0235º)

In your imagination now, substitute your moving car for the wall and imagine that the officer pans from a point at the rear of your car at the start of the measurement to a point at the front of our car at the end. Because your vehicle is moving it is entirely possible that the instrument can pan through an arc of 0.02 degrees and still be focussed on the vehicle at the end of the 0.3 second period (a traverse of about 10 metres at 400 metres). The spurious speed obtained by the panning effect may then be added to the actual speed of the vehicle, thus giving the impression of very high speed… and you being on the receiving end of a speeding citation.

The ruling that the laser speed measuring equipment must be mounted on a tripod on a firm and stable surface and NOT mounted in or on a vehicle is related to the panning effect in that small movements of the instrument during the measuring period can give rise to profoundly incorrect readings.

Again with the example of the wall the following table shows the effect of a small horizontal movement (Angle ß) can have on the measurement of the speed at which the wall is apparently approaching the observer”

It is theoretically possible for a nudge or bump of the instrument resulting in a lateral movement of about four thousandths of a degree to add a spurious speed of 20 KmH to the actual speed of the vehicle, which is more than enough to put you apparently over the speed limit and result in the citation. This small degree of movement is clearly possible with the instrument mounted in or on a vehicle if an occupant therein moves and causes weight transference on the vehicle’s suspension and consequent movement of the

SME. The panning effect and absolute necessity for the laser speed measuring equipment to be extremely stable during the actual measurement has been explained in some detail because it is critical to an accurate measurement and thus to afford readers of ammunition to be used in argument either with the prosecutor before going to court or in evidence in court to cast reasonable doubt on the validity of the speed trapping exercise.

I repeat that it is a common sight to see Cape Town’s traffic officers conducting speed traps with the instrument mounted in their vehicle and that in itself should be sufficient grounds to have any charge dismissed… but if you are bust, remember the other matters mentioned and don’t just accept the assumption of guilt and pay the fine… if the road-user is expected to obey rules, then so are the traffic officials and before simply paying up… make sure the officers were doing it the way their rule book says it must be done.

Next month I hope to provide a summarised checklist of things you can and should demand from the authorities should you be charged with speeding resulting from laser speed measuring equipment. Hopefully this may be set out in the form of a draft or template of a letter that could be addressed to the appropriate authority.

RAY STROUD