Traffic management can be one of the more expensive and complex issues facing municipal managers. And if something goes wrong, the town or city is sure to hear about it. Even simple traffic systems can be difficult to monitor, maintain, and repair.
Without clear visibility into the status of each traffic light's control box, lights can fail before municipal managers are aware, risking collisions and expensive repairs. So, municipal managers turn to SCADA traffic control monitoring to keep their traffic flowing smoothly.
Supervisory control and data acquisition, or SCADA, allows municipal employees to monitor the status of their traffic lights, whether there are two in town or two million.
Supervisory control and data acquisition, or SCADA, allows municipal employees to monitor the status of their traffic lights, whether there are two in town or two million. SCADA itself isn't a product - it's a concept - a system in which distant pieces of hardware communicate with a central node.
SCADA enables employees to watch and, in some cases, control every traffic light in the city from the same chair. Depending on the municipality, different SCADA traffic control strategies can be used to improve traffic flow, reduce malfunctioning lights, and lower maintenance costs.
The simplest and most direct application of the SCADA concept to municipal traffic control is system monitoring, which - more specifically - is a system of effective equipment monitoring.
Traffic lights have equipment cabinets, usually located at their feet or corners of intersections. If the equipment in the cabinet is working, so is the traffic light.
So how is it done? By adding a gear that will act as a traffic control device to each equipment cabinet. This is known as an RTU (remote terminal unit). RTUs can track environmental conditions inside equipment cabinets, warning municipal managers if temperature or humidity threatens the operation of traffic lights.
RTUs can track environmental conditions inside equipment cabinets, warning municipal managers if temperature or humidity threatens the operation of traffic lights.
RTUs can be used to detect other issues, such as flooding, unauthorized physical entry, or voltage deviations. If an issue is detected, RTUs transmit the information to the appropriate responder. This represents the "Data Acquisition" portion of SCADA.
For small traffic grids - with a dozen lights or less - RTUs can directly inform the maintenance crew leads of problems. Once grids become larger and more complex than this, it becomes more efficient to route alarms to a master station.
A central master station sorts, prioritizes, and informs dispatchers and managers of problems by order of importance.
Large cities may further subdivide their traffic grids into multiple regions - each watched over by an individual master station. This allows regions to deal with problems locally. By transmitting information to a central master station - which displays it in a browser - city-level managers can:
Supervisory control visibility gives managers time to dispatch maintenance services to correct the problem. Situations to consider include:
SCADA architecture is like the Roman roads - they all go to Rome. As described previously, anything that happens in the network transmits to a central control station: "Rome."
Well, roads go two ways. In more advanced SCADA systems:
If summer heat threatens equipment function, the RTU can be commanded to turn on the AC. But once the roads have been laid and the network architecture is in place, commands can also go to the traffic lights themselves.
RTUs within a SCADA system allow city managers to alter traffic patterns at need, in response to accidents, large events like concerts, or dangerous situations like a fire or flood. This is another facet of the "Supervisory Control" portion of SCADA.
While central traffic control may sound appealing, in reality, responding to changing traffic needs at every light 24/7/365 takes more employees than can possibly be assigned. At that point, the city might as well just give up on traffic lights and send policemen with flags and radios to every intersection. So, traffic patterns are largely automated with emerging technologies as outlined below.
In this instance, SCADA is used to keep an eye on artificial intelligence (AI). While not actively changing traffic patterns themselves, retaining the ability to do so and override AI decisions helps city managers prevent or reverse unwise decisions made by autonomous-thinking machines.
With all the added hardware involved in AI control - like cameras, pressure plates, and the computers themselves, RTUs become even more important.
With all the added hardware involved in AI control - like cameras, pressure plates, and the computers themselves, RTUs become even more important. RTUs help monitor and maintain the functionality of simpler SCADA systems. RTUs also enable managers to receive alarms about potential problems and dispatch technicians to repair hardware issues.
By using SCADA architecture and implementing a traffic control monitoring system of RTUs, municipalities can reduce costs and improve service. Traffic flow improves, repair costs are lowered, and accidents are prevented through monitoring and automation.
Image courtesy Unsplash, Roberto Junior
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