A Disaster Prevention Support System Using Rivers and the Ocean

The maintenance of an extensive transport network system that organically ties up land, sea and air is a major point in the discussions involving earthquake counter measures. An infinite amount of small and large rivers flow through the plains on which large cities sit. These river routes need to be characterized as an extension to ocean routes and used more effectively to promote the improvement of the transportation network.

Disaster response operations integrating land, sea and air

One of the greatest regrets about the 1995 Hanshin-Awaji Earthquake was that the region´s abundant seas, port facilities, open spaces and airspace were not effectively utilized,in an integrated approach linking land, sea and air, to tackle the disaster. Though great efforts were made to incorporate land, sea and air routes into disaster-prevention planning, in each case the best routes were selected on an individual basis, not as cohesive parts of a comprehensive,three-route plan. In a truly integrated approach, earthquake barriers, for example, could be used not merely as barriers but as takeoff and landing facilities for helicopters and as transportation links for the delivery of goods and access to the open spaces where residents could take refuge. Admirably, Kobe´s earthquake barriers withstood the quake, but it satisfied none of the other conditions listed above.
 Immediately after the earthquake, the development of a wide-area transportation network was proposed, linking land, sea and air and built in partnership between the public and private sector. In 1995 and 1996 the National Land Agency, Ministry of Transport and Ministry of Construction (now amalgamated in the Ministry of Land, Infrastructure and Transport (MLIT)) joined with the Fire Defense Agency (now Fire and Disaster Management Agency) to assess the cost of a comprehensive land development project for this purpose, in a study called the "survey to determine measures to promote the formation of an integrated land, sea and air network in the Tokyo area." The survey dealt with four themes: the construction of disaster prevention bases for the Tokyo area as a center for wide-area support and other disaster prevention efforts extending across prefectural borders; formation of a river-based emergency transportation network; use of ports as centers for disaster prevention activities; and securing and distributing supplies of household water.
 Proceeding in parallel with these efforts is the Megafloat project, a plan to devise a large-scale floating structure for disaster prevention purposes. While the idea of creating an artificial, floating island in place of land has been around for over 20 years, it was only in the 1990s that the Transportation Technology Commission published findings that prompted real progress in research and development on the topic. The Commission was particularly interested in the fact that, while land-based structures sustained massive damage in the Hanshin-Awaji Earthquake, floating docks in shipyards emerged unscathed. That year a technical research consortium was formed, consisting of 17 shipbuilding and steelmaking companies. Megafloat was conceived as a mobile port facility and an "offshore wide-area disaster prevention base" for the Tokyo area, capable of supporting a river-based emergency transport network. Proving tests were conducted in Yokosuka Bay to float a prototype measuring 300m in length, 60m in width and 2m thick. After these tests, six units were linked together in 1999 to create a Megafloat that was 1000m long, 60m wide (120m wide in some parts) and 3m thick (with a draft of 1m).
 As part of the Megafloat research effort, proving tests were conducted to assess its function as a disaster prevetion base and offshore airport. In autumn 2000, after the research and proving tests were completed, Megafloat was dismantled and put to other uses. In the ports of Osaka,Nagoya and Yokohama, these "minifloats" were docked with cargoes in the 1000t range and deployed as floating disaster-prevention bases with heliport capabilities.
 In a separate effort, the Research Institute for Ocean Economics (RIOE) initiated research on a "system for disaster prevention support from seas and rivers" immediately after the Hanshin-Awaji Earthquake. This proposal clearly demonstrated considerable promise. RIOE´s report envisaged a 16m ship for river transport, with a draft of 1.5-2m when fully loaded and a height of 3m above the surface when empty. Assuming that the ship would require bridge clearance of 3m or more, waters at least 2m deep in dry season or at low tide and an upstream limit point of 20m (to enable turnarounds), the distance the vessel would be able to travel upriver from Tokyo Bay would be 29km on the Arakawa River, 22km on the Edogawa, 10km on the Tamagawa and 9km on the Tsurumigawa. Of these four, the river with the greatest potential utility is the Arakawa. Today a river bus operates along a 34km stretch of the Arakawa, with a capacity of 206 passengers and draft of 1.25m.
 Yet another plan, advanced by MLIT, calls for the construction of six river stations on each side of the Arakawa River, in a 30km stretch from the river´s mouth. Dubbed the Arakawa River Station Plan, this scheme aims to facilitate river transportation during normal times and facilitate emergency response in the event of earthquakes or similar events. Although some safety issues remain to be solved regarding the use of rivers in disaster response, if these can be conquered a vast new transportation network can be opened up to serve the Tokyo area.

In MLIT´s Arakawa River Station Plan, 12 "river stations" will be built along the Arakawa River, establishing an emergency transportation route to Tokyo Bay. Above is an artist´s conception of the Toda river station with a 30m floating wharf.

A new urban transportation network for Japan´s aging society

 If this river route is to be made available in times of crisis, measures must be taken to stimulate its use in normal times. Such a project amounts to nothing less than the creation of a new mode of river and marine transportation.
 If I may finish on a somewhat unrelated note, another new transportation network is emerging in the form of the three- and four-wheel electric vehicles, with a top speed of 6km/h, favored by the elderly today. In my own hometown,my mother loved her electric cart, and my 91-year-old father, taking her lead, uses one constantly to go shopping,visit the hospital or meet friends. These little vehicles are everywhere now, from big cities like Tokyo to regional centers like Nagaoka. Even though electric carts are only permitted on footpaths, many people cheerfully drive them on roads and highways. I believe the day is not far off when these little cars will throng city streets in huge numbers.Although it will start with brief journeys for daily tasks, I believe that elderly people living along Tokyo Bay, the banks of rivers and the Koto delta will soon use their beloved buggies to go shopping or sightseeing in Asakusa,Ginza, Tokyo Disneyland and Yokohama´s Minato Mirai 21. The new water transportation systems should soon make such travel possible, in fact, it is hard to imagine such travel patterns without them.
 I believe that within 10 years we will see crowds of elderly people on their electric buggies. They will up and down rivers and along the shores of Tokyo Bay in countless craft both large and small, side-by-side with children and young adults on their bicycles.