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Red light violations: camera installation requirements

1. The detection of a “Red light” violation requires installation of video cameras that monitor entry to the intersection, exit from the intersection, cameras that detect traffic light signals, and overview cameras. Each function requires a corresponding type of video camera as listed in Table 1.

Table 1

Camera functionAbbreviation
License plate recognition of vehicles entering the intersection. Detection of crossing a virtual line (stop line)LPR
License plate recognition of vehicles leaving the intersection. Detection of crossing a virtual lineLPR
Traffic light signal detectionTL
Panoramic overview video cameraOV

2. Video cameras for license plate recognition of vehicles at entry and exit of the intersection (LPR).

2.1. An example of LPR camera placement is shown in Figure 1 (red indicates entry cameras, blue indicates exit cameras).

Figure 1.

Diagram of an intersection showing LPR camera placement and fields of view, with red cones marking entry cameras and blue cones marking exit cameras at each approach

2.2. To generate traffic violation events, the LPR camera installation must comply with the requirements specified in Table 2.

Table 2

CharacteristicRequirement
Tilt from 10° to +30°
Panfrom –20° to +20°
Rollfrom –5° to +5°
Image quality at the boundary of the controlled zone300 pixels/meter or higher
Illumination of the controlled zone50 lx or higher across the entire scene
Camera mounting heightFrom 6 meters ot higher above the road surface. The highest possible mounting height is recommended to reduce vehicle occlusion.

2.3. LPR field-of-view configuration recommendations:

  • Cameras must capture front license plates at both entry and exit.
  • Entry cameras must also capture the stop line (if present), located in the second third of the frame horizontally.
  • Exit cameras must include the intersection area in the upper part of the image.
  • Cameras should be installed as high as possible within the limits specified in Table 2.
  • Figure 2 below shows the example images from entry cameras, Figure 3 - from exit cameras.

Figure 2.

Entry LPR camera view of a van and a red SUV crossing the intersection stop lineEntry LPR camera view of three SUVs traveling side by side toward the intersection across multiple lanes
Entry LPR camera view of a crossover vehicle approaching the intersection with lane-direction arrows painted on the roadEntry LPR camera view of two sedans approaching the intersection stop line on a wet road with a timestamp overlay

Figure 3.

Exit LPR camera view of a truck driving away from the intersection across marked parking and lane linesExit LPR camera view of two dark SUVs having crossed the intersection exit line onto the roadway
Exit LPR camera view of a sedan and other vehicles exiting the intersection past a pole-mounted camera housingExit LPR camera view of a pedestrian with a bicycle crossing a marked crosswalk near the intersection exit, with vehicles waiting nearby

3. Cameras for traffic light signal detection (TL).

3.1. An example of TL placement is shown in Figure 4.

Figure 4.

Diagram of an intersection showing TL camera placement, with shaded triangular fields of view aimed at each traffic light and its stop line

3.2. TL installation must comply with Table 3.

Table 3

CharacteristicRequirement
Tilt from +5° to +30°
Panfrom –45° to +45°
Rollfrom –5° to +5°
Image quality150 pixels/meter or higher
Illumination10 lx or higher
Mounting height6 meters or higher

3.3. TL camera field-of-view recommendations:

  • Install on the same side as the traffic light or as high above the roadway as to exclude obstruction of the traffic light by big vehicles.
  • Minimum height: 6 m. If the traffic light is above 4 m, install the camera 2–3 m higher.
  • The field of view must include up to 10–15 m of roadway.
  • For more than three lanes, use two cameras on the opposite sides of the roadway.
  • Figure 5 shows the example images from TL cameras.

Figure 5.

TL camera view of a multi-lane approach with vehicles in the distance and a turn-lane arrow marking on the roadTL camera view of a person and vehicles near the stop line with a visible traffic light signal at the intersection approach
TL camera view from beneath an overpass showing a vehicle at the stop line, an illuminated traffic light, and pedestrians on the sidewalk in the rainDiagram of an intersection showing OV camera placement, with a large shaded field-of-view zone covering the whole junction from a diagonal mounting position

4. Additional overview cameras (OV) for general monitoring, evidence generation, and improved detection of secondary vehicle features at night.

4.1. Example placement shown in Figure 6.

Figure 6.

OV camera wide shot of a paved intersection with lane markings and parked cars in the distance, with a timestamp overlay

4.2. OV cameras must comply with Table 4.

Table 4

CharacteristicRequirement
Tilt from +15° to +75°
Panfrom –75° to +75°
Rollfrom –5° to +5°
Image quality50 pixels/meter or higher
Illumination10 lx or higher
Mounting height5 meters or higher

4.3. Recommendations regarding OV camera field-of-view:

  • Mount cameras as high as possible.
  • Place diagonally across the intersection to reduce occlusion.
  • Figure 7 shows the example images from OV cameras.

Figure 7.

OV camera wide shot of an intersection approach with dashed guide lines and buildings visible in the backgroundOV camera wide shot of a wide multi-lane intersection with sparse traffic and roadside buildings in view
OV camera wide shot of several vehicles crossing an intersection curve with a roundabout-style road layoutOV camera wide shot of an intersection beneath an overpass with a vehicle and pedestrians visible on a wet road