Determination under section 146A(3) and section 146D Land Transport Act 1998 made by the Director of Land Transport after consulting with the Surveyor-General appointed under section 5 Cadastral Survey Act 2002 as required by section 146A(3).

1. Title and date from which this determination applies

1.1 This is the Land Transport Method for Measuring Distances in Average Speed Camera Systems Determination 2025.

1.2 This determination applies from 19 September 2025.

2. Interpretation and definitions

2.1 In this determination unless the context otherwise requires—

Act means the Land Transport Act 1998

terms defined in the Act have that meaning unless defined differently in this determination—

• detection point (see section 2),
• Director (see section 2),
• intermediate surveyed distance (see section 146A(3)),
• point-to-point average speed system (see section 2),
• surveyed distance (see section 146A(3)).

acceptable coordinate system means coordinates in terms of the national survey control system provided for in section 4 and section 7(1)(b) Cadastral Survey Act 2002, including—

• New Zealand Geodetic Datum 2000,
• New Zealand Vertical Datum 2016.

camera means the approved vehicle surveillance equipment (approved under section 2 of the Act) which detects vehicles at a detection point.

corridor means the formed road between the two detection points of an average speed camera system.

GIS means geographic information system and includes generic and survey-specific applications.

GNSS means Global Navigation Satellite System.

GPS means the Global Positioning System.

inflection point means a point at which a change in the direction of curvature occurs.

INS means Inertial Navigation System.

operator means the entity which operates or is responsible for an average speed camera system.

route means a path through a corridor determined under clause 7.

specified quality, for data, and the techniques, methods, and equipment used to carry it out, means of the quality described in table 6.1.

surveyor means a cadastral surveyor licensed under Part 3 Cadastral Survey Act 2002.

Surveyor-General means the statutory officer appointed under section 5 Cadastral Survey Act 2002.

transect means, in the case of straight parts of the corridor, a line normal to the centre line at an inflection point and in the case of curved parts of the corridor means the shortest line from the inside of the curve at the inflection point to the line or edge of formed road on the other side.

2.2 diagrams are not necessarily to scale and depict detection points as being in the centre of lanes.

3. Method for measuring surveyed distances and intermediate surveyed distances

3.1 In the cases where there is only one speed limit over the corridor the method is as set out in clauses 2 to 10 and the surveyed distance is the length measured in accordance with clause 8.

3.2 In cases where there is more than one speed limit over the corridor the method is set out in clauses 2 to 11, and the intermediate surveyed distances and the surveyed distance are those measured in accordance with clause 8.

4. Marks and information to be supplied by operator

4.1 The operator must supply a name for the corridor based on the names of roads or localities.

4.2 The operator must provide the surveyor the means to identify the points at which the average speed camera system detects the presence of a vehicle for the purposes of determining the time to be used by the system in calculating the average speed of the vehicle.

4.3 Subclause 4.2 can be complied with by providing any or all of – marks or objects on or off the formed road, data, including bearings and survey related data, for example using the methods illustrated in figures 1(a), 1(b), 2(a), and 2(b).

4.4 Subclause 4.2 applies for each direction of travel if the average speed camera system operates in both directions.

4.5 Marks or objects placed for the purposes of this clause may (but need not) be in place after the method has been carried out.

Figure 1(a)

Figure 1(b)

Figure 2(a)

Figure 2(b)

5. Surveyor must survey camera and markers and get data to calculate the route along the corridor

5.1 The surveyor must identify the detection points using the means provided under 4.2 and survey their location to the specified quality.

5.2 The surveyor must define the following at the specified quality in terms of an acceptable coordinate system

• the corridor,
• the road centreline along the corridor,
• elevation along the corridor,
• the edge of formed road along the corridor.

6. Specified qualities

6.1. The quality required of data used in the method, the techniques, and equipment used to carry it out is specified in this table –

7. Defining the route through the corridor

7.1. Definitions for clause 7

7.2. Route starts and ends near detection points

The route starts at a point on the centreline closest to the first detection point and ends at the point on the centreline closest to the second detection point, for example as shown by the thick red lines in figures 1(a), 1(b), 2(a), and 2(b) and is, between those points, determined as provided for in—

• 7.3 (which relates to straight parts of a corridor),
• 7.4 (which relates to parts of a corridor that follow curves),
• 7.5 (which relates to cases where straight parts meet curved parts).

7.3. Straight parts of a corridor

Over straight parts of a corridor where lanes are not separated by a central barrier the route is along the centre line (see definition in 7.1) and is the same for both directions of travel, as illustrated in figures 3, 4, 5 and 6.

Figure 3

Figure 4

Figure 5

Figure 6

7.3.1. Over straight parts of a corridor where lanes are physically separated by a central barrier the route is half-way between the inside of the central barrier and the left-hand edge of the corridor in the direction of travel and is illustrated in figure 7.

Figure 7

7.4. Parts of a corridor that follow curves

For parts of a corridor that follow curves and have no central barrier the route is in sections along the inside edge of each curve from the first point of inflection, and then in sections to the next point of inflection such that transitions between sections are defined by a transect normal to the edge of the corridor such that the transect does not itself form part of the route, illustrated in figure 8 in which the route is illustrated as the red lines (A-B + B-C) and applies for travel in both directions.

Figure 8

7.4.1. For parts of a corridor which follow curves and lanes are physically separated by a central barrier, the route is in sections along the shorter of the inside edge of each curve or inside edge of the barrier from the first point of inflection, and then in sections to the next point of inflection such that transitions between sections are defined by a transect normal to the edge of the corridor such that the transect does not itself form part of the route.

• Illustrated in figure 9 in which the route is illustrated as the thick red lines (C-D + D-E) and applies for the direction of travel C to E also shown by the arrows.
• Illustrated in figure 10 in which the route is illustrated as the thick red lines (C-D + D-E) and applies for the direction of travel E to C also shown by the arrows.

Figure 9

Figure 10

7.5. Where straight parts meet curved parts

Where a straight part of a corridor meets a curved part of the corridor the route is along the centreline as provided for in 7.3 until the inflection point of the curve, from where the method in 7.4 is used, the transition being defined by a transect normal to the edge of the corridor such that the transect does not itself form part of the route illustrated in figure 11 below.

Figure 11

8. Using GIS, calculate the length of the route in three dimensions

8.1. The surveyor must use GIS software to measure the length of the route in three dimensions to the highest accuracy possible given the accuracy of the data that forms the inputs (see table 6.1), and that length is the surveyed distance.

9. Driving corridor

9.1 The surveyor must drive the corridor with a GNSS or INS twice along the line that would typically be taken by a person driving a typical light passenger vehicle along the corridor between the two detection points and calculate the mean distance across both runs.

9.2 If the average speed camera system is to operate in both directions, performing the tasks in 9.1. for each direction.

9.3 The surveyor must use a vehicle on which a rover is mounted as part of a GNSS system or an INS with the specified quality (see table at 6.1).

9.4 This clause exists to provide accurate base data for the operator to understand how systems such as a survey accurate GNSS systems or consumer grade GPS might record the distance a vehicle travels along the corridor. It has no necessary relationship to and is not relevant to the route determined in accordance with clause 7 nor the surveyed distance measured in accordance with clause 8.1.

10. Elements of the method may be carried out on behalf of surveyor

10.1 Any part of this method may be carried out by any person or automated process if the surveyor can have sufficient confidence that those elements are carried out in accordance with this method to give the statement in clause 12.1.

11. Additional elements in cases where there is more than one speed limit in the corridor

11.1 Where there is more than one speed limit in the corridor the elements of the method must be carried out in relation to both—

• the surveyed distance; and
• the intermediate surveyed distance or distances.

11.2 If 11.1 applies—

• the operator must (in addition to the material described in clause 4) give to the surveyor a description of the spatial extent of the speed limits in the corridor including boundaries between them (see the table clause 6.1),
• the elements of this method must be applied by the surveyor with any necessary modifications to apply the formula in section 146B of the Act (which relates to an average weighted speed limit).

12. Material to be provided by surveyor to Director

12.1 The surveyor must supply to the Director—

• a visual depiction in plan-view and long-section of the route,
• source files (in a commonly used format or formats) from the GIS software used,
• measurement outputs from GNSS equipment in DWG, DXF, CSV, or RINEX,
• a table quantifying in metres errors in extracting the geometry of the route,
• a table recording how the instructions in clause 7 were applied in detail to relevant features in the corridor (with an estimate in m of the difference from the most plausible counterfactual),
• a statement of the sensitivity (in km/h) of the Average Speed Camera System to differences in the surveyed distance of 1m, 10m,
• the distances measured under clause 9,
• statement by surveyor in the form in Schedule 1.

12.2 Nothing in this clause 12 restricts the Director or the operator contracting with the surveyor to provide any other data or services.

Dated this 27th day of August 2025.

CHRIS RODLEY, National Manager Regulatory System Design, Acting under delegated authority from the Director of Land Transport.

Endnotes

1. https://www.linz.govt.nz/system/files/2022-10/New%20Zealand%20National%20Aerial%20LiDAR%20Base%20Specification%20v1.2.pdf.

2. https://www.linz.govt.nz/sites/default/files/2025-04/New%20Zealand%20National%20Aerial%20Imagery%20Base%20Specification%20-%20Draft.pdf.