Among the things you get to observe at signalized intersections are the behavior of drivers given the setting of the traffic lights. While the cyclic transition from red to green to amber and then to red again seems routine and possibly trivial to many, it is an opportunity for traffic engineers to examine how drivers react to the lights. Among the most notable behavior are common violations like beating the red light and occupying the area within the yellow box despite full awareness that the exit is already full.
Then there are the not so obvious but risky habit of some drivers to beat the green light. That’s when a driver anticipates the green light and proceeds to move prior to the signal and before the intersection is clear of any vehicles or pedestrians that may have been caught in the change in signals. It is a practice that increases the probability of a road crash occurring as the clearance interval for vehicles whose paths may be in conflict is drastically reduced. This is a habit of many drivers who are familiar with the sequence of signals at an intersection and who know when its their turn for the green light.
In most cases, drivers and pedestrians are unaware of the length of time available for them to cross the street or intersection. There are no indications for when the lights will change and only familiarity would allow for drivers or pedestrians to estimate when it would be their turn to proceed. In Japan, many intersections play music during that tends to speed up when the signal will be changing. This audible indicator allows for both the blind and the busy to know whether it is safe to cross the street and if there is enough time to do so. It is also something that is probably taught to children for them to more easily know when it is safe for them to cross the street.
There is another innovation to traffic signals that is surely welcome to pedestrians and motorists alike but which may also have its disadvantages. I am referring to the countdown timer, which provides road users the information about the lengths of green and red signals (Note: Amber or yellow is usually fixed at 3 seconds.). From the perspective of energy efficiency, such information may allow motorists to turn off their engines, usually done when one practices eco-driving, resulting in fuel savings. Meanwhile, drivers of vehicles approaching an intersection may be able to tell if there is enough time for them to do so, and if there isn’t enough time they may be able to slow down their vehicles to stop at the next red light. Countdown timers may also be a helpful tool for enforcement as the timers establish that a driver should be aware of the time. Thus, a driver can no longer reason with the apprehending officer that he/she was not aware of the remaining time for movement.
Pedestrians may also benefit from the knowledge of available time to make a safe crossing. This information should ultimately reduce the need for running in order to completely cross the street. The photo below shows the new countdown timer installed for the southbound through movement at the Katipunan Avenue (C5) – C.P. Garcia Avenue intersection.
One possible disadvantage would be that aggressive drivers may still try to beat the red light by speeding up upon knowing what amount of time is available for them. Another disadvantage relates to beating the green light as even those unfamiliar with the signal sequence will have the information of how much time remains before they can proceed. Thus, many driver and riders start revving up their engines and push on their gears to anticipate the green signal. You can even imagine the countdown timer being used as if it were ticking towards to start of a race.
Despite the disadvantages mentioned, countdown timers should prove to be more beneficial than detrimental in most situations. In fact, countdown timers like the ones already installed at intersections in Bonifacio Global City should enhance traffic safety provided that these devices are fully complemented by enforcers who would flag down motorists and pedestrians who would attempt risky actions in relation to the timing device. Of course, from the research perspective there needs to be a scientific assessment of the actual impacts of countdown timers much like the studies already conducted elsewhere to determine and even measure the effects of these devices on both motorists and pedestrians. Only then can we truly say if they do enhance safety and promote more efficient operations at a signalized intersection.
Since last week, it seemed as if a ghost of Christmas past has come to haunt me and my colleagues at the NCTS. We had some unexpected visitors from the Traffic Engineering and Management (TEAM) group of the Department of Public Works and Highways (DPWH). They were at the Center to consult about a project being formulated by the group together with the MMDA for new traffic signals for Metro Manila. DPWH-TEAM has a long history with NCTS starting when that unit was created when the Philippines invested on its first coordinated traffic signals in the 1970s.
At that time, the NCTS was still the Transport Training Center (TTC), and was the site of the first traffic control center for signals that were installed along Quezon Avenue. The package was funded by a loan from the Japanese government and hence involved traffic signals manufactured by Mitsubishi. Years and many TEAM project phases later, most of Metro Manila’s major intersections would be signalized and traffic signal control would be under the Traffic Engineering Center, which until 2003, was under the DPWH. In the 1990’s, the TEC and TEAM worked together to acquire the Sydney Coordinated Adaptive Traffic System (SCATS), which at the time was already installed and running in most major intersections in Cebu City.
SCATS was supposed to usher in a new era in traffic control in Metro Manila until some major problems eventually plagued its operation. One of these problems was power. However, this was something everybody else was concerned with because of the power crisis of the early 1990s. It was also something that seemed to be easily solvable with the acquisition and installation of uninterrupted power systems (UPS) and generators that allowed the facility to operate even during blackouts.
Another technical problem cropped up just about the same time when the TEC and TEAM people were trying to solve the power issue. This time, it was something much more complicated and perhaps, what led to the system losing its credibility in Metro Manila and a chain reaction of sorts in as far as reactions go. The communications problem was a critical one and rendered the system practically unreliable for what it was supposed to solve – congestion. SCATS required a reliable network for its controllers and computers to communicate with each other. This communication allowed its software to assess network-wide traffic demand measured by means of detectors embedded in the pavement at each approach lane of an intersection. Data from these detectors are transmitted to computers in the control center, which then compute for the optimum cycle times for each signalized intersection. The computers determine which intersections need to be coordinated and how (i.e., alternating or simultaneous), and this process allows SCATS to adapt to variations in traffic. Hence, its name which seemed only appropriate given its performance in what is now the expanded network in metropolitan Cebu.
The failure of SCATS in Metro Manila was further hastened by traffic enforcers who were only too eager to intervene. This intervention was more of interference as enforcers started switching the traffic signal controllers to manual mode at the slightest indication that the signals would appear to be non-responsive to changes in the traffic situation. In truth, it takes a few minutes for the detectors to collect data and send it to the computers that will compute for the appropriate cycles and signal settings as well as determine which intersections to “marry” and “divorce” – to borrow terms used by traffic engineers in Cebu City for the process of coordinating intersections throughout the day. Due to this rampant practice by enforcers in Metro Manila, it was only a matter of time before SCATS was declared a failure and claims were made that Metro Manila traffic is so much more complicated than Cebu’s, where SCATS was a success (it still is today).