DMR supports communication in Kinmen tunnels

In the sightseeing tunnels in Kinmen, communication devices like mobile phones cannot operate and the humid environment in the tunnel can easily damage general communication devices. How to maintain the timely and reliable communications in case of emergency is a significant challenge.

Kinmen, governed by the Taiwan government, is the strategic stronghold between the mainland and Taiwan. It is located on the west side of Taiwan Strait and southeast of Fujian province across the sea. With the shortest distance away from the mainland, Mashan (in Kinmen) and Jiaoyu (in Fujian) are only 2310 m apart. For historical reasons, many tunnels and air-raid shelters had been dug in advance.

With the alleviation of the relationship between the mainland and Taiwan governments, the tunnels and air-raid shelters have been developed by the Cultural Affairs Bureau of Kinmen County into destinations for tourists; therefore, the higher requirements on the emergency communications and rapid response in the tunnels were needed.

They wanted a complete communications solution applicable in such adverse situations to be applied in all sightseeing tunnels under management, including communication terminal, management system and network establishment.

A sightseeing tunnel 1 km in length was selected and 26 points were set in the tunnel. An emergency call device was distributed at each point and the communication in the tunnel would be maintained via leakage cable.

A dispatching centre was established outside the tunnel, with a view to monitor the communications throughout the tunnel. Tourists could use the nearest communication device to call the dispatching centre under an emergency situation. Four communication devices were established outside the tunnel to provide services for patrol personnel.

Hytera focused on the practicality of the solution based on the tunnel’s requirements.

Considering the high humidity in the tunnel, PD782 DMR portable radios with IP57 water protection were selected as the communication terminals. A waterproof box in which the radio would operate was added for better protection, and communication was conducted with a handheld microphone connecting to the radio out of the waterproof box.

The radios were required to be operating in uninterrupted stand-by state. Common conventional batteries, however, could not comply with the requirement due to their limited service time. As a result, Hytera designed a battery box to supply the power directly when being connected to DC, eliminating the problem.

For effective management of radio communication, the SmartDispatch DMR dispatching solution was used and special functions were tailored on the basis of existing software for the project.

To monitor the terminal status, the console needed to back-check the status of the radios (on/off line) following the sequence from No.1 to 26 by the system. The amount of data required to be processed was limited as only one or two back-checks are needed every day, therefore only one MD782, which acts as a gateway, and one console client were required in this configuration.

In addition, four radios were to be used by patrol guards which only need to communicate with the console.

The operation and management efficiency improved significantly due to the system customised for the project. Moreover, the emergency handling scheme was rather consistent with requirements.

“We couldn’t know clearly about the situation in the tunnel in times when emergency strikes, as the cable lines were damaged due to the humidity in the tunnel. Now the digital wireless system installed by Hytera not only improves significantly the mobility, but also displays the correct position on the computer screen immediately and the ultraclear voice quality is unmatched by the traditional communications,” said the leader of the Cultural Affairs Bureau of Kinmen County.

“We are very satisfied with and amazed by the products from Hytera and expect such solution will be promoted and used in the following project.”