IR-01-26-741
21 January 2026
Lee
[FYI request #33418 email]
Dear Lee
Thank you for your Official Information Act 1982 (OIA) request received 4 January 2026
in which you requested information on radar equipment in New Zealand. I have answered
each part of your request below.
1. Please provide a copy of the Road Policing manual;
•
Police Policy for col ecting evidence using a radar unit;
•
Operation instructions use; and
•
What is required for evidence to be reliable that supports context?
Please find included with my response a copy of the
Speed Detection Device Operators
Manual. Al radar/laser equipment used by Police must be operated in accordance with
the
Speed Detection Equipment Operators Manual.
The
Speed Enforcement Chapter also may be of interest to you, which is publicly
available on the Police website, here:
https://www.police.govt.nz/sites/default/files/publications/speed-enforcement-270325.pdf
2. What are the pitfalls of use of equipment in certain weather conditions? And what
conditions are not suitable to for use?
Weather conditions such as rain, mist, and fog can reduce radar range and weaken the
return signal. NZ Police radar units are equipped with a sensitivity control that allows
operators to adjust the strength of the received signal to suit the environment. Under
normal conditions, the sensitivity should be set to level 4 (the highest setting) to ensure
quick and accurate speed detection. In rainy conditions, reducing the sensitivity may help
maintain effective detection.
These conditions do not affect the accuracy of the displayed speed.
This is detailed on page 15 of the
Speed Detection Device Operators Manual included
with my response. Please see this page for further information.
3. What wil cause the readout to jump and give a non-consistent speed?
Traffic radar operates in the super high-frequency range (24–38 GHz), which is general y
free from environmental noise and interference. While some sources, such as high-
tension power lines, air traffic control radar, and airport navigation systems, are often
Police National Headquarters 180 Molesworth Street. PO Box 3017, Wellington 6140, New Zealand.
Telephone: 04 474 9499. Fax: 04 498 7400. www.police.govt.nz
cited as potential causes of interference, testing by NZ Police and the Measurement
Standards Laboratory of New Zealand (MSLNZ) found no impact from these sources on
the radar equipment used by NZ Police.
Occasional intermittent readings may occur under certain conditions, but most
interference sources do not produce a Doppler tone. A clear Doppler tone indicates an
accurate, interference-free target speed.
For further information, refer to pages 15 (Atmospheric Conditions) and 23 (Possible
Sources of Interference) of the
Speed Detection Operator Manual.
4. Can conditions prevent the radar from picking up the target and send back an
accurate reading?
Certain weather conditions, such as rain, mist, and fog, can reduce radar range and
weaken the return signal. However, these conditions do not prevent the radar from
detecting a target or returning an accurate speed reading. NZ Police radar units include a
sensitivity control that operators can adjust to maintain effective detection in varying
conditions.
For further information, refer to page 15 (Atmospheric Conditions) of the
Speed Detection
Operator Manual.
5. For a reading to be demeaned accurate does the speed on the readout unit need
to be consistent, and
•
Does the tone need to be constant and unwavering?
•
What happens if the Dopler tone is inconsistent?
For a speed reading to be considered accurate, a tracking history of the vehicle must be
established. This involves three key elements:
1. Visual observation of the target vehicle
2. Audio confirmation through the Doppler tone
3. Verification by the speed detection unit
Al three elements must be present for each speed check to effectively eliminate errors.
A clear and consistent Doppler tone indicates an accurate, interference-free reading. If
the Doppler tone is inconsistent, the operator should not rely on that reading as accurate.
Note: A clear Doppler tone is the operator’s indication they have an accurate,
interference-free, target speed.
For further information, refer to page 7 (Tracking History) and page 23 (Possible Sources
of Interference) of the
Speed Detection Operator Manual.
6. Is the unit adjusted for weather conditions? And;
•
What adjustments can be made to the sensitivity of the unit reading at
the low and high end?
•
What is the main use of this function?
•
What occurs when the unit sensitivity is turned down?
Radar units can be adjusted for weather conditions using a sensitivity control that
manages the strength of the return signal. Under normal conditions, the sensitivity should
be set at level 4 (the highest setting) to ensure quick and effective speed detection. In
adverse conditions such as rain, the sensitivity may be reduced to maintain detection
capability. The main purpose of this function is to optimise radar performance in varying
atmospheric conditions, ensuring that signals received are suitable for the environment.
When the sensitivity is turned down, the strength of the received return signal is reduced,
which helps the radar continue detecting vehicle speed during rain or similar conditions.
Importantly, these adjustments do not affect the accuracy of the displayed speed.
7. To give evidence contexts must any photographs of alleged speed be
accompanied with the officer’s notebook with the traffic stop recorded? And/or a
photograph of the readout with the vehicle in the background for context and
evidential value?
There is no evidential requirement for Police to obtain photographs as part of speed
enforcement. Each offence is assessed on its own merits in Court, and Police must
produce sufficient evidence to prove the charge. This may, but does not necessarily,
include photographs presented as exhibits. While officers may take photographs (for
example, of the readout or scene) where appropriate, there is no requirement to obtain or
produce a photograph, nor to pair any photograph with notebook entries, to prove an
alleged speeding offence. Notebook records of the stop and other evidential material wil
be considered alongside any exhibits, as required, to meet the standard of proof.
8. Can you use photograph as evidence if there is no date, time, defendant or
vehicle in the photograph to tie the al eged speed to the event, (i.e. evidence
without context to the event)?
The admissibility and weight of photographs as evidence are governed by the rules of
evidence and are ultimately matters for the Court. In some circumstances, a photograph
without date, time, defendant, or vehicle identifiers may stil assist the prosecution (for
example, to depict the general road layout or surrounding environment). However,
evidential relevance and probative value are assessed on a case-by-case basis.
Accordingly, it is not possible to provide a blanket rule on the use of undated or
de‑contextualised photographs; their use wil depend on how they relate to the specific
offence and the totality of the evidence presented.
If you are not satisfied with the way I have responded to your request, you have the right
under section 28(3) of the OIA to ask the Ombudsman to review my decisions.
Information on how to do this is available online at
www.ombudsman.parliament.nz.
Yours sincerely
Superintendent Steve Greally
Director: Road Policing
New Zealand Police
