‘Intelligent’ traffic signals coming to Miami-Dade

Overview Miami-Dade’s department of transportation and public works.
Overview Miami-Dade’s department of transportation and public works.

Until 2011, traffic lights operating in Miami-Dade County were largely controlled from a room in Northwest Miami-Dade where technicians monitored the system from a giant board on which each signal was represented by a light bulb that glowed red or green. Red meant something was wrong.

That board is gone and the room is now filled with computers and flat-screen TVs where technicians control traffic lights and monitor major intersections in real time through images of moving traffic relayed by cameras mounted on the signals.

The change in the control room is part of a multimillion-dollar modernization program to upgrade the almost 3,000 traffic signals in the county. The upgrade involves new computers that run the signals as well as new equipment that makes each signal operate more efficiently thus improving the synchronization of traffic signals in the county.

“The traffic light system was my very first initiative when I arrived,” said Alice Bravo, director of the county’s department of transportation and public works, who joined the ranks of county officials in 2015. “We have the infrastructure and in an era of ever-improving technology, we need to improve the efficiency and effective capacity of the roadway system. Anything we can do to improve the throughput of the roadways with the use of technology is going to help our commuters.”

Anything we can do to improve the throughput of the roadways with the use of technology is going to help our commuters

Alice Bravo, director of the county's department of transportation and public works

The modern era of traffic signals in Miami-Dade dates back to 1975 when the old control room was built. It was a state-of-the-art system at the time and traffic engineers from around the world trekked to Miami to see it, county officials say.

Officials coordinated signals from the control room via telephone lines. It was vast darkened room where each traffic signal lit up as an individual small light on a large board. Most glowed green meaning they were working and not off line.

While the room was operational after 2000, it was gradually phased out. The last remnant of the old control room was unplugged in 2011, 36 years after it became operational.

When the control room was dedicated, it had a capacity for about 2,000 traffic signals. But as Miami-Dade County grew, the control room exceeded capacity by the 1980s.

Over the next few years, county technicians tweaked the system to add capacity — but the control board remained in place with the traffic lights flashing red or green.

It wasn’t until Miami-Dade voters approved a half-cent sales tax for transportation that the county got serious about modernizing the traffic signal management system.

By that time, 700 more signals had been added in Miami-Dade but they could not be coordinated because the control board did not have the capacity.

Today, county officials say, the system had added more signals for a total of almost 2,900. As the urban population grows, so does the traffic signal system. Between 20 to 40 signals are added every year.

The increase in population has also led to an increase in traffic, which has exceeded the capacity of the roads in Miami-Dade. This excess in traffic, county officials say, is the reason for a growing number of complaints by drivers who are convinced that the traffic signals are not synchronized and that the county needs to improve its coordination of the devices.

The traffic situation in our city is becoming worse every day

L. De Jaham of Doral

“The traffic situation in our city is becoming worse every day,” L. De Jaham of Doral said in a recent email. “Apart from the ever increasing number of vehicles on the road, one of the main culprits is the poor timing and synchronization of traffic lights.”

But during a detailed briefing on the county traffic signal management system, officials said that while glitches occur, the signals are largely fully coordinated.

“There are failures in equipment,” one senior traffic official said. “But generally the signals are coordinated.”

For example, morning traffic from the suburbs in the west to downtown office buildings in the east is rewarded with more green lights. In the afternoon, the pattern is reversed with more green lights for traffic heading back to the the western suburbs.

Also at major intersections, traffic signal technicians have eliminated left-turn signals to allow quicker circulation of eastbound traffic in the morning and westbound traffic in the afternoon.

Normal coordination occurs when a cluster of vehicles can get four or five green lights ahead as it moves like a platoon at peak times.

For example, on U.S. 1 from Southwest 16th Street to 98th Street, the traffic signals are synchronized.

So, when a platoon of vehicles gets a green light at 16th Street, it is supposed to get four or five green lights in succession along U.S. 1 — as long as the vehicles move at the same speed and don’t run into an accident or some other obstacle at intersections, county officials said.

The platoon often slows down and misses the succession of green lights if vehicles on cross-streets are blocking the intersection or one of the drivers fails to move forward when the light turns green.

Between 2006 and 2011, the traffic management system was upgraded.

Today, the county is moving toward “intelligent” traffic signals that work with cameras to monitor traffic at major intersections and also reprogram their timing by themselves to respond more quickly to changing traffic conditions.

The continuing modernization drive is being implemented in two phases. The first phase is to gather information about traffic patterns along major corridors like U.S. 1 south of Interstate 95.

“We’re installing cameras and testing vehicle information systems to obtain more information,” one of the technicians said.

County technicians are exploring options about emerging traffic signal technologies and testing different systems.

Some of these technologies include traffic lights that communicate with each other and are able to detect approaching vehicles, extending green or red lights as needed.

“As we have different initiatives to improve our roadway systems, ultimately the real solution is to get more and more people to use mass transit,” Bravo said.

Alfonso Chardy 305-376-3435, @AlfonsoChardy