Live traffic cameras
MoDOT has cameras installed along interstate highways and state routes in the St. Louis area. The video from these cameras is live, not recorded, and they help MoDOT’s Transportation Management Center operators monitor traffic flow. The operators can use the cameras to identify potential congestion-creating incidents, such as crashes and stalled vehicles, and are able to direct the appropriate emergency response forces to those incidents. The cameras are also used to monitor the backup from road work zones. Operators use this information to convey messages to the public to detour motorists away or around these congestion points.
Video and photos from the cameras are only available in real time and are not stored. During crashes or incidents, cameras may not remain pointed at recovery efforts as operators continue to monitor the flow of traffic behind the incident. Since traffic is slow or stopped, the potential for additional crashes is increased during major incidents, and operators need to watch for those crashes and direct emergency response forces there, as well.
Camera views and videos are provided on MoDOT's Gateway Guide to offer drivers the opportunity to review and evaluate the flow of traffic on their projected route, and determine if they need to use an alternate route. Camera views are also provided to the local media through agreements to provide additional information in media traffic reporting efforts.
A camera retrofitted to an existing pole system
A camera mounted on the arm of a signal pole.
A camera connected to the arm of a signal using a pipe extension.
The red rectangles are the "zones" drawn via processor software to target the areas to detect vehicles. They can determine if traffic is waiting at the stop bar or approaching the signal.
Signalized Intersection Cameras
MoDOT uses cameras at signalized intersections solely for detecting the presence of vehicles in order to adjust signal timing, as needed, based on traffic demand. They are cost-effective replacements for in-ground induction loops that are cut into the pavement.
The cameras are not focused on the drivers of vehicles, but instead on the vehicle as it moves towards the intersection. Often, signals during rush periods are timed to help improve the flow of traffic. Outside of those times, they may operate using detection. When the vehicle enters the defined detection areas or "zones" within the camera's field of view, the camera's processor detects a change in the "zone." That alert is sent to the signal's controller (the computerized "brain" housed in a nearby metallic cabinet controlling the intersection's timing) that says a vehicle is requesting green time for its direction. If there is not other, higher priority traffic, the signals are then changed accordingly to provide a green light for the incoming traffic at the intersection.
Why are the cameras attached to the signals so high?
A higher mounting position allows for a better angle and wider view, which in turn generally lets one camera to cover all lanes in a particular direction. Lower mounting heights (at signal indications' height) would not provide an effective image. MoDOT generally looks at mounting heights of around 30 feet, which is at least 10 feet above the height of the signal indications.
Who is watching me through these cameras?
There is no constant surveillance or archiving of these images. The camera view is a fixed focus, fixed location image (there is no zooming or moving the cameras once they are installed). The image is analyzed by the camera processor ONLY for the simple presence of vehicles within defined areas or "zones". The resolution of the image by these cameras is NOT good enough to read license plates or distinguish any facial features.
Will I get a ticket if I run the red light or speed through the intersection?
These particular cameras are in no way tied to any law enforcement system. They are solely for detecting the presence of vehicles within their view. They are not capable of producing an image detailed enough to read license plates or facial features.
Some municipalities do have red light enforcement cameras. The few on state routes are installed and maintained by the municipality (not by MoDOT), have to meet requirements of Missouri law and are marked
Is my privacy being violated?
No. First of all, the cameras are focused on public property and are not aimed onto private property. Secondly, the cameras and their processor are incapable of displaying or sorting through an image which yields any distinguishing features or identification. Highway cameras only determine the volume and speed of traffic to indicate if there is an incident. Traffic signal cameras only notify the signal controller if a vehicle is approaching the signal.
How long are the videos kept?
There is no recording of these cameras. The video is analyzed by the processor in real-time, with no storage whatsoever of the image stream.
Are signal cameras tracking my movements?
Absolutely not. The cameras on signals are incapable of producing an image which renders any specific identification of the vehicle or driver. The camera processor's only function is to determine if a vehicle is within the predetermined "zones". It has no surveillance capability.
Why go through the extra expense of installing cameras?
Cameras are now the most cost-effective way of performing vehicle detection. Previously, the primary method of vehicle detection was done by cutting the pavement a few inches and installing a wire "loop" just below the surface. This "loop" is charged with a small electric current originating from the traffic signal control cabinet. As a metal object (i.e. vehicle) travels through the electric current's field, the change in the inductance from the metallic object triggers an output that a vehicle is within the "loop." The signal controller responds by changing the signal appropriately.
These in-ground loops have both near-term and long-term costs. The labor for a work crew to saw-cut pavement while shutting down that lane of traffic, and the cost of material (wire, conduit, loop processors) are immediate costs. In the long run, additional costs pile up. The saw cutting of the pavement weakens its strength, resulting in shorter service life and more maintenance costs for pavement repair. When in-ground loops fail, the entire loop must be recut into the pavement again, so the labor and traffic disruption costs are renewed.
Video detection cameras, like most electronics, have seen their costs steadily drop since the technology was first introduced. Camera processors, like all computers, have increased their capability as prices drop. Installation is done above the surface of the road, and usually away from the flow of traffic. The pavement remains undisturbed and is capable of lasting longer. When cameras or processors fail, they are simply and quickly replaced without a great disturbance in traffic flow.
Comparing the overall costs of the in-ground loops vs. the overhead cameras today gives the cameras the edge. It is an efficient use of taxpayer money for the job they perform.