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Newsletter "SEI NEWS" 2014

Home > Company Information > SEI WORLD > Back number > Vol.445

[Newsletter "SEI WORLD" Vol.445]

Traffic Signal Controller with a Built-in Battery

Traffic Signal Controller with a Built-in Battery

The red, yellow and green traffic lights we see everywhere in urban areas are indispensable for automobiles and pedestrians to safely and smoothly pass through or cross roads. Let’s take a look at a product that can steadily operate traffic lights.

■Product data
Start of sales September 2013
Production base Japan

What is a traffic signal controller with a built-in battery?

A traffic signal controller, when connected to a centralized control system, controls the lighting time of traffic lights in response to command signals from the traffic control center. This controller thus controls the traffic lights in response to traffic demand to ensure safe and smooth road traffic and also to create an environment-conscious road traffic environment. Conventional traffic signal controllers are powered by commercial power. If the commercial power fails due to a lightning strike or other cause, the traffic lights will turn off and can disrupt the traffic flow.

Like conventional traffic signal controllers, the newly launched controller with a built-in battery is usually powered by electricity from the grid. However, if the grid fails, the power supply of the new controller is automatically and instantly switched to the built-in battery, thereby preventing the traffic lights from turning off. For an ordinary intersection, the new controller with a fully charged battery can operate the traffic lights for at least three hours.


Where is the new controller used?

The newly launched traffic signal controller is installed near an intersection. Approximately 60 new controllers have already been installed at major intersections in Tokyo. When a large-scale power outage occurred in Tokyo after these new controllers were installed, they worked as expected and prevented the traffic lights from turning off.

■Interview with engineer in charge

Mr. Kenichi Minamimura ITS Development Center, ITS and Infrastructure Unit
, Sumitomo Electric System Solutions Co., Ltd.

What motivated you to develop the traffic signal controller?

We were inspired by the large-scale traffic disruption caused by power outages after the Great East Japan Earthquake. After the Earthquake, rolling blackouts were implemented in Tokyo. Many police officers were called out to direct traffic. To meet increasing demand for traffic signal controllers that could prevent traffic lights from turning off, we started to develop a traffic signal controller with a built-in battery.

What problems did you face in the course of the development?

Since the traffic signal controllers are installed near intersections where automobiles and pedestrians pass and cross, the dimensions of the enclosures are restricted. We made a supreme effort to build a battery in a conventional enclosure.

Though we used smaller parts for the switching device and changed the parts arrangement in the enclosure, we could not secure sufficient space to house a battery in the enclosure. As an alternative, we developed a smaller-sized battery jointly with one of our associated companies. The newly developed battery was small enough to be housed in a conventional enclosure. Safety is required of traffic signal controllers because they are installed near places through which automobiles and pedestrians pass. Within a restricted development period of approximately eight months, we took sufficient time to assess and ensure the safety of this product.

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