today 137

Earthquake-proof: new sleepers for Japan’s high-speed lines

In western Japan, derailment prevention guards are employed to protect trains from derailments caused by earthquakes. The modern SES 170 sleeper exchange system by Plasser & Theurer installs these sleepers efficiently. ​

Nozomi Kitamura
Shinkansen Operations Division, Shinkansen Track & Structures Department, JR West

Until now we were only able to exchange a maximum of 40 sleepers, manually or with excavators, in a single shift. That was all. Now, with the SES 170 by Plasser & Theurer our output is fivefold.

Earthquakes in Japan – safe railway infrastructure

There are approximately 2,000 earthquakes in Japan every year. Most of the earthquakes are minor tremors and go unnoticed, but even larger earthquakes are not uncommon and cause damage. They also affect railway infrastructure. Earthquakes are a fact of life. This is why Japan puts preventive measures in place to minimise damage, for example, in the western part of the country on the San-y-Shinkansen line.

This high-speed line operated by the West Japan Railway Company (JR West) is 553.7 km long. The trains on this line transport more than 230,000 passengers per day. The San-y-Shinkansen line plays a vital role for Japan’s mobility. JR West is taking various structural measures to improve travel safety and to reduce damage: employing derailment prevention guards is one of them. A new type of sleeper is used to install them. The plan is to exchange the sleepers on the entire line as quickly as possible. This is where the SES 170 comes in.

​ We have been working with the SES 170 since September 2016. So far, the machine has been in operation for over 300 nights. ​

The SES 170 sleeper exchange system

The SES 170 sleeper exchange system is 94 m long. It consists of three main components: a transport wagon with gantry unit and crew cab (on the right); the main machine in the centre with sleeper manipulator, suction unit with ballast hopper, and ballasting unit; and a power wagon (on the left). Basically, the SES 170 exchanges sleepers and restores the track geometry. Apart from the start and end of work, the sleepers are exchanged semi-automatically. The system can exchange approximately two sleepers per minute.

Exchanging sleepers precisely and continuously

After the site has been prepared manually, the SES 170 suction units clear away the ballast surrounding the sleepers. Now it is possible to move them. When work begins, the sleeper manipulator pulls twelve old sleepers forwards in the working direction. It removes four sleepers in order to create an open space of 2,400 mm. The manipulator rotates the sleepers by 90 degrees. It then lifts and transports them to the sleeper lift which takes them to the first level of the machine. These sleepers are then transported to a sleeper conveying system and deposited in groups of five. The machine’s gantry unit can transport up to five sleepers at once. It takes them from the sleeper conveying system to the transport wagon.

After the open space has been created, the system switches to continuous operation. One sleeper is removed from the front part of the open space. At the same time, a new one is installed at the rear. A fixing unit steers the newly laid sleepers to the correctly centred position. Then, it fastens the sleepers to the lifted track. Now, the ballast hopper supplies the correct quantity of ballast. The ballast is then stabilised. The gap in the open space is closed with new sleepers to allow opening the line for rail traffic during the day.