Maintenance and Repair of Roads and Bridges

Tokyo’s roads support the lives of residents and will serve as lifelines for evacuation and relief operations in the event of a disaster. In addition, as a vital part of the nation’s transport network, these roads are essential infrastructure that support social and economic development.

In order to ensure that these roads are kept in good condition and traffic can safely pass, the Bureau is constantly engaged in road maintenance and repair.

As part of maintenance and repair programs, a range of inspections are conducted on an ongoing basis, including daily patrol inspections, regular periodic inspections, and emergency inspections conducted in response to events such as heavy rain. By accurately grasping the condition of the roads, the Bureau is carrying out maintenance, scheduled repairs, and reinforcement work.

In order to ensure the safety of road users, the Bureau uses patrol cars to conduct daily inspections, looking for issues such as damage to or the decay of roads and bridges, road obstructions or debris, and problems with road lighting, and takes the appropriate measures to respond.

Taking into account the characteristics of each route, inspections are generally scheduled for once every three days. Annually, the Bureau discovers over 50,000 cases of damage to roads and other abnormalities.

In addition, the Bureau also carries out maintenance including street and street gutter cleaning, repainting of bridges, and resurfacing of bridge decks.

By conducting a pavement condition survey once every three years, the Bureau measures cracks, ruts (depressions), and pavement evenness on all roadways, except for those located on the Tokyo islands, and evaluates the data using the Maintenance Necessity Index (MNI).

Based on the results of the survey, locations in need of repair are selected and priority for repair is established. By systematically carrying out surface repairs, the Bureau provides drivers with a safe and pleasant ride. In addition, along with road repairs, improvements with respect to steps and gradients are being made to sidewalks.

The Bureau is paying careful consideration to the environment along roads, using noise reducing pavement and two-layer noise reducing pavement in areas where measures to reduce noise are needed, and heat shield pavement and water-retentive pavement where measures to mitigate the urban heat island effect are needed.

Through scheduled inspections conducted out once every five years on all road facilities (tunnels, underground walkways, retaining walls, common ducts, etc.), the Bureau finds abnormalities or damage to road facilities early, takes the necessary steps, and carries out planned repairs and reinforcement, ensuring safety for road users.

Starting in fiscal 2012, detailed testing to determine the structural soundness of all tunnels was conducted over a course of two years. The first stage of tests included imaging and laser scanning of tunnel walls and lining. Tunnels that were found to exhibit damage were then put through a second stage of testing that included close visual inspection, hammer tapping, inspection by feel, testing for cavities behind the tunnel lining, and testing of the concrete. Based on the test results, swift measures are being taken for tunnels in need of immediate repair, while a preventative maintenance plan that compiles required measures has been drawn up for all tunnels. Through these inspections and by carrying out scheduled maintenance and reinforcement, the Bureau is ensuring tunnel safety.

As important means of urban transport in local communities, new transportation systems and urban monorails have contributed to the development and promotion of areas along the route. Today, while supporting the everyday lives of the people, they also play a major role in creating prosperity and vitality in communities.

The infrastructure that supports new transportation systems and urban monorails, including support columns, track girders, switches, station roofs, barrier-free facilities, and concourses, is managed by the road administrator as a part of its road facilities. By systematically maintaining and repairing these facilities based on inspection results, the Bureau is ensuring the smooth function of the capital’s transport systems and increased convenience and safety for users.

When compared to other types of energy efficient lighting (ceramic metal halide lamps and high-pressure sodium lamps) LED lamps consume less electricity and have a longer life. As such, the Bureau is working to optimize management efficiency by switching to LED lighting, starting with street lights that can be converted.

In order to achieve efficient maintenance and management of road facilities and work toward improved disaster response capabilities, the Bureau is working to employ the use of Information and Communication Technology (ICT).

With respect to routine operations, inspection of road facilities that utilize radio frequency identification (RFID) technology are being conducted on the Shinjuku Fukutoshin Route No. 4.

The Bureau also operates the Rescue Navigation System. When a natural disaster occurs (earthquake, flood, or snow-related), GPS-enabled cell phones are utilized to promptly and accurately gather information on road damage, which is then stored in a database. This system aims to facilitate effective information sharing between Bureau headquarters and offices. Additionally, on some roads in mountainous areas, the Bureau has set up equipment such as cameras and rain gauges, which allow Bureau headquarters and offices to check local conditions, in order to enhance disaster response capabilities.

In order to ensure that emergency and evacuation operations will run smoothly when a disaster strikes, the Bureau is working to seismically reinforce bridges such as those on or over emergency transport roads. By carrying out these repairs, bridge collapses are being prevented prior to a disaster occurring.

This program works to extend the life of prominent bridges highly valued as cultural assets, including the Kiyosubashi, Eitaibashi, and Kachidokibashi bridges which span the Sumidagawa River, long span bridges for which the cost to rebuild and impact on the surrounding area would be great, bridges that cross over railways and roads, as well as bridges of main arterial roads

The bridge life extension program ensures safety and peace of mind by upgrading bridges to make them even more durable through repairs and reinforcement measures that utilize the latest technologies and materials. The Bureau aims to extend the lifespan of bridges to 100 years beyond completion of reinforcement measures.

The Bureau conducts regular periodic inspections on all bridges once every five years. Based on the inspection results, the appropriate repairs and reinforcement measures are carried out ensuring safety.

Roads in the mountainous regions and islands of Tokyo are essential parts of the infrastructure. It can also be said that these roads are the lifelines that support the livelihood of residents and economic activities in the area. The implementation of safety measures on hillsides and slopes is extremely important in preventing disasters on these roads. On mountain roads, regular periodic inspections are carried out once every five years and the condition of hillsides and slopes is fully assessed. Based on the results of this inspection, safety measures are systematically implemented in order of the locations in most urgent need.