Safer crossing: The tactile unit for visually impaired people is a yellow box with a vibrating device at its base.

About 11,000 Electronic Audible Traffic Signals have been erected to help people, including the visually impaired, cross roads safely.

Transport Department Senior Engineer Li Chi-chiu said the devices are divided into two types - one for all pedestrians and another for the visually impaired.

The one with a palm symbol and red cap is a push-button-cum-tactile unit for all pedestrians. It is activated once a pedestrian presses its lower yellow portion engraved with a palm symbol. Then a "beep" sound is generated and the message "please wait" will be displayed on the red cap indicating that a demand for the pedestrian green has been registered. The traffic signal controller will soon give the green signal to the pedestrian.

Capacity optimised

Mr Li said: "The device is provided to optimise traffic capacity at junctions with heavy vehicular traffic and low pedestrian flow. The pedestrian signal will not turn green until it is activated by pedestrians through the push-button unit. Pedestrians who want to cross the road are required to press the button and then wait for the signal to turn green before crossing."

The tactile unit, on the other hand, lets visually impaired people know when it is safe to cross the road.

It is a wholly yellow box without a press-button function or red cap signal. Instead, a vibrating unit is set at the bottom of the device to provide different vibrating patterns according to the prevailing states of the pedestrian signal. In collaboration with the audible unit mounted close to the signal, the device provides guidance for visually impaired people wanting to cross the road.

The tactile unit helps them confirm that the correct audible traffic signal is heard and this is particularly useful at junctions with a number of pedestrian crossings close together.