- Email: [email protected]
Anti-inundation Measures for Underground Stations of Tokyo Metro
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 165 (2016) 2 – 10
15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development”
Anti-inundation measures for underground stations of Tokyo Metro Yoji Aokia,*, Atsushi Yoshizawaa, Tomoya Taminatoa a
Tokyo Metro .Co. Ltd, 3-19-6, Higashi-ueno, Taito-ku, Tokyo, Japan
Abstract Tokyo Metro Co., Ltd. (hereinafter, Tokyo Metro) comprises nine lines operating over 195.1 km and 179 stations, and is used by 7.07 million passengers per day. Tokyo Metro operates on the belief that security equals safety plus service. In regard to safety, special effort is devoted toward countermeasures for natural disasters. In light of recent extreme weather events, countermeasures for heavy rains are particularly important. It was reported in the updated expectations for flood damage published in 2009 that metropolitan area’s 17 lines and 97 stations and 147km of the tunnels will be completely submerged underwater. In response to expectations, we are developing and installing various waterproofing facilities at all tunnel entrances, ventilation openings, underground station entrances and other openings. Among these, underground station entrances are expected to suffer the most damage. Most Tokyo Metro station entrances are situated on sidewalks, there are many obvious spatial restrictions. In light of these restrictions, conventional waterproofing doors (hinged doors that apply positive pressure against floodwater pressure) cannot be used to improve all entrances, thus we have continued to develop counterpressure doors, hinged double doors, shutters, bi-fold doors and other types of waterproofing doors that fit the environments of individual entrances. In addition, few of the many buildings to which Tokyo Metro tunnels connect underground are prepared for the updated expectations for flood damage, meaning that Tokyo Metro must take action on its own property to prevent flood water inundation from such buildings. This means taking flood control measures in underground concourses with severe spatial limitations. Thus, we have developed counterpressure sliding doors capable of withstanding water pressure from flooding up to 15 m deep. This report describes updated expectations for floods, Tokyo Metro’s improvement policy and descriptions of various types of underground waterproofing doors and the performance required of them. 2016Published The Authors. Published by Elsevier ©2016 © by Elsevier Ltd. This is an openLtd. access article under the CC BY-NC-ND license Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under theSustainable scientific committee of the 15th International scientific conference “Underground Urbanisation as a Urbanisation as aresponsibility Prerequisiteoffor Development. Prerequisite for Sustainable Development Keywords: Underground Station, Subway, Flood Control, developed.
* Corresponding author. Tel.: +81-33-837-7195 E-mail address: [email protected]
1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development
doi:10.1016/j.proeng.2016.11.730
3
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
1. Introduction Tunnels stretch across 168.6 km (158 stations) of Tokyo Metro subway lines, and roughly 90% of this total length is underground. Recently published updated flood expectations predict major damage to the entire metropolis of Tokyo due to water flowing into tunnel entrances and other openings turning the tunnels into wastewater pipes. Most concerning is water flooding into entrances, and a pressing challenge is to find flood control measures for both Tokyo Metro entrances as well as those from adjacent buildings (“petition entrances”). Our assumptions are based on a tsunami simulation for the Tokyo Metropolitan area, in the case of a vertical shock earthquake (Tokyo Bay northern earthquake M7.3) and a trench type earthquake (Genroku type Kanto earthquake M8.2 and Nankai-trough earthquake M9). These simulations assume that a tsunami would not breach the existing Tokyo Bay embankment. 2. Existing Tokyo Metro Flood Control Measures As measures against the flooding of roads by overflowing rivers, typhoons or sudden rains, Tokyo Metro has long installed water stop plates (Figure 1 shows one that is 750 mm tall) at entrances and flood preventing machines (Figure 2 show one that works for flooding up to 2 m) at ventilation openings in lowlands and depressions, as well as watertight gates (Figure 3) at some tunnel openings near lowlands and rivers. We have installed tide gates (Figure 4 shows a positive-pressure waterproofing door) at station entrances as a measure against storm surges in sea-level areas. In addition to these flood control measures, sump pumps discharge rainwater and other water that flows into tunnels.
Fig. 1. Water Stop Plate.
Fig. 2. Flood Fig.
Fig. 3. Watertight Gate.
Fig. 4. Outward Waterproofing Door.
3. Updated Expectations for Damage of Major flooding (collapse of levees on the Arakawa/Tonegawa Rivers) In January 2009, the Central Disaster Management Council (a Japanese cabinet committee) published a report of expected damage, in the event of a collapse of the Arakawa River levees. There are 2 scenarios, first with heavy rain that could be expected to occur once in 200 years (550 mm3 per day) and second with severely heavy rain expected to occur once in 1,000 years (638 mm3 per day). These predictions showed flood damage reaching central Tokyo and submerging most subway stations. Specifically, 17 lines, 97 stations and 147 km of tunnels in Tokyo would flood, and floodwaters would inundate central Tokyo around three hours after a levee collapse, putting Otemachi Station under as much as 1.8m of water (hereinafter Major flood). Figure 5-1 is a simulation of flooding 72 hours after the collapse of an Arakawa River levee in the 1,000-year case. In addition, heavy rain in the Tokai region (September 2000, 534 mm3 in 24 hours) prompted city administrators to publish hazard maps that expected depth of inundation in depressions due to the overflow of small and mediumsized rivers during sudden rains and other flood events(Figure5-2). (hereinafter Urban flooding).
4
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10 Fig.5-1. Expected Inundation Zone 72 Hours After Arakawa River Levee Collapse.
Arakawa River Point of collapse Nanboku line of Tokyo metoro Chiyoda line of Tokyo metoro
Above-ground inundation depth ■㻌 0.2-0.5 m ■㻌 0.5-1.0 m ■㻌 1.0-2.0 m ■㻌 2.0-5.0 m Below-ground inundation ■ Tunnels completely full ■ At least 2 m ■ At least 5 cm □ No inundation Hnzoumon line of Tokyo metoro
Yurakutyo line of Tokyo metoro Tozai line of Tokyo metoro Marunouchi line of Tokyo metoro Ginza line of Tokyo metoro Hibiya line of Tokyo metoro Central Tokyo
Source: Simulation of flooding in subways,etc., Japanese cabinet
Figure 5-2: Chiyoda City Expected Inundation Zone
Inundation Depth ■ 0.2-0.5 m ■㻌 0.5-1.0 m ■㻌 1.0-2.0 m ■㻌 2.0-5.0 m
Inundation area due to river overflow Chiyoda City Inundation area due to sudden rain
Source: Chiyoda City Flood Evacuation Map (flooding hazard map)
5
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
4. A New Direction for Flood Control Measures Tokyo Metro’s utmost priority is the preservation of human life. We are determined to take action against urban floods and major 1,000-year floods and seal all openings leading to tunnels to reduce damage and expedite the rehabilitation of underground spaces after flooding. We will also undertake flood control measures for aboveground facilities that must be promptly rehabilitated, such as transformers and signal transmission equipment housing (Figure 6). There are 612 facilities which connot cope with the current inundation predictions. Specifically, 473 facilities at station entrances, 102 facilities at ventilation openings, 5 facilities at tunnel entrances and several others (Table 1). A total investment of 20 billion yen and 10 years starting in 2013 have been budgeted for these improvement plans. Petitioner entrance Tokyo Metro Ventilation entrance tower
Office Bicycle parking
Above-ground station Station office
Ventilation opening
Entrance to tunnel
Signal transmission
Connecting entrance
Station office
concouse
Transformer room
Equipment Electric l room room Elec
Water stop point shows location of flood control ৌੁ measures ਜ਼઼॑ घ
Platform
Fig. 6. Tokyo Metro Flood Control Measures. Table 1. The inundation mesures point (at 2013).
Flood control measures Total
stations
Subway
Item
Not needed*
Needed
Tokyo Metro
608
360
248
Petitioners
331
167
164
20
61
Other businesses 81 Emergency exits
24
16
4
Above-ground stations
53
25
28
Total
1093 588
Flood preventing machines 959
857
505 102
6
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
Entrances to tunnels
20
15
5
5. The Surrounding Environment in Relation to Flood Control Most Tokyo Metro station entrances are placed on sidewalks, which means there are spatial limitations - extra sidewalk space cannot be secured or restrictions on the minimum clearance outline on the road side exists. Thus, some entrances cannot be improved with positive-pressure swing doors (Figure 4) that are already developed. In addition, the condition of petitioner entrances is such that very few building owners have already completed or plan to undertake measures against 1,000-year floods, but many building owners are rather concerned that water from tunnels will inundate the buildings. Because rainwater flows into stations from petitioner buildings when urban floods and major floods occur, the only option is to undertake flood control measures onTokyo Metro property. Thus, it is assumed that flood water inundation of the underground concourse could reach a depth of up to 10 to 15 m. 6. Flood Control Facilities in Stations When developing flood control facilities there is a requirement to set an allowable leakage volume, but currently the only exisiting standards were set by the Old Ministry of Posts and Telecommunications (0.02 m 3/m2h). Thus, each manufacturer sets its own standards. Power companies and others like them have set standards below 0.02 m3/m2h, and Tokyo Metro followed suit. However, leaks of 0.02 m3/m2h at all inundation points (over 500 in all) during a major flood would submerge over 300m of tunnel beneath 1.5 meters of water. Therefore, we have been aiming for absolutely no leakage at all as we progress in development with manufacturers. Station personnel will operate the facilities during disasters, so we considered the following points during development: the ease of operation regardless of age or gender and the possibility of manual operation during power outages. Because station personnel will eventually evacuate the stations themselves, waterproofing doors will need to be opened and closed from both the inside and outside. In addition, since most entrances cannot be expanded, we developed waterproofing doors that should fit within the existing entrance areas as much as possible. 6.1. Water stop plates (for flooding less than 1 m) We decided to use conventional water stop plates (Figure 7) to control flooding less than 1 m deep, but they weigh 12 kg each, making them difficult to carry up stairs. Thus, we switched the material from steel to aluminum to reduce the weight to roughly 6 kg. Note that water stop plates are initially set at the first lowest level (around 35cm tall as in Figure 8) to ensure that passengers can evacuate during the early stages of flooding.
Fig. 7. Water Stop Plate (up to 1 m).
Fig. 8. Water Stop Plate at the First Level
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Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
6.2. Horizontal Bi-Fold Two-Level Water Stop Doors (for flooding less than 1.5 m) Water stop doors are installed where flooding exceeds 1 m, but some existing sidewalk entrances require significant expansion but approval cannot be gained for sufficient expansion due to reasons such as traffic flow on sidewalks and intersection visibility (Figure 9). Thus, we developed bi-fold water stop doors set to function of evacation during the early stages of flooding (Figure 10). This reduces the expansion of occupation area required and enabled the improvement of this type of entrance. The development of these facilities resulted in the successful cutoff of nearly all leakage. Water stop door New wall (expanded area)
Water stop plate
Fig. 9. Entrance with Insufficient Space.
Fig. 10. Bi-fold Water Stop Door.
6.3. Waterproofing Shutters (for flooding less than 2.0 m) When flooding exceeds 1.5m, side horizontal bi-fold water stop doors lose their ability to withstand water pressure at their folds. Thus, we decided to use positive-pressure waterproofing doors (Figure 4), but as explained previously, in some cases due to the problem of the road control, we could not gain approval for sufficient expansion. In other cases installing a waterproofing door and Access Control Shutters would make the entrance too large. In addition to these design problems, these factors negatively affect visibility of nearby buildings insome cases, making it difficult to gain the understanding of localresidents.In light of limit the sizes of entrances to their original dimensions, we developed waterproofing shutters that can be used as Access Control Shutters (Figure 11). The slats are designed in a panel figure, and electric cylinders are used to act pressure on the slats horizontal and vertical direction for creating water stop lines (Figure 12). These shutters have the capacity to stop roughly 2 liters/m2h of water.
㻮 㻭
Fig. 11. Waterproofing Shutter.
Fig. 12. Waterproof Mechanism.
6.4. Counterpressure waterproofing doors (for flooding of 2.0 m) Waterproofing shutters stand around 500 mm taller than normal shutter boxes, and their housing above sidewalk entrances in front of stores negatively affect visibility. Therefore, it is sometimes impossible to gain the understanding of local residents. Thus, Tokyo Metro developed counterpressure waterproofing doors (Figure13),
8
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
which were widely reported by various media outlets as they were the first waterproofing facilities of our genuine flood control effort. We tested these doors for leaks using high-pressure jets and confirmed that there were no leaks.
Fig. 13. Counterpressure Waterproofing Door.
6.5. Horizontal Bi-fold Waterproofing Doors (to prevent submersion) Positive-pressure swing doors (Figure 4), waterproofing shutters (Figure 11) and counterpressure waterproofing doors (Figure 13) cannot be installed at building entrances because there is not much space between stairs and the edges of roads, ceilings are not high enough and the entrances themselves are wide. Thus, we developed positivepressure horizontal bi-fold waterproofing doors (Figure 14). These doors have the capacity to stop roughly 1 liter/m2h of water.
Fig. 14. Horizontal Bi-fold Waterproofing Door.
6.6. Vertical Bi-fold Waterproofing Doors (to prevent submersion) Waterproofing shutters and counterpressure waterproofing doors cannot withstand flooding over 2 m and thus cannot be installed at entrances expected to become submerged. Using only positive-pressure waterproofing doors (Figure 4) is possible, but as explained previously it is difficult to obtain approval to occupy roads, there are design problems and it is difficult to gain the understanding from local residents due to reducing visibility. Thus, we developed vertical bi-fold waterproofing doors (Figure 15). They are stored into the roof, and they are equipped with a feature that enables their use as electric maintenance shutters during normal operations (Figure 16). The motors are completely protected from water and can open and close the doors when entrances on the sidewalks are submerged. It is also possible to open and close the doors manually if the power supply is cut off. These doors have the capacity to stop roughly 1 liter/m2h of water.
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
Fig. 15. Vertical Bi-fold Waterproofing Door.
Fig. 16. Overhead Door.
6.7. Counterpressure Waterproofing Sliding DoorsˋHinged Counterpressure Waterproofing Double Doors Flood control measures at petitioner entrances are for expected flooding at a depth of 10 to 15 m, because they have to be undertaken within Tokyo Metro property, namrly within our subway concourse. Highly reliable and affordable positive-pressure waterproofing doors (Figure 4) have been used because many petitioner buildings are connected to Tokyo Metro properties by passageways that are quite narrow. On the other hand , some petitioner entrances have no passageway between the buildings and stations (Figure 17). To counter this, we developed counterpressure waterproofing sliding doors (Figure 18) that make it possible to undertake flood control measures from petitioner entrances. However, the sliding door’s pocket may not be installed because there is unmovable room(Figure 19)(ex: electric room). There for, we developed hinged counterpressure waterproofing double doors capable of withstanding flooding up to a depth of 15 m (Figure 20). These doors are nearly watertight, but the utmost care is required to position the door frames because a strong pull-out force acts on the existing structure.
Fig. 17. Petitioner Entrance with no passageway.
The machine which is impossible of transferencee ↓ Sliding door’s pocket is impossible of setting
concourse
Fig. 18. Counterpressure Sliding Door.
Petitioner entrances
Counterpressure Double Door is possible
Fig. 19. Petitioner Entrance with no Sliding door’s pocket.
Fig. 20. Hinged Counterpressure Waterproofing Double Doors.
9
10
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
7. Conclusion As explained above, the development stage is approaching its end, and we have entered to the design and construction stages. Construction is roughly 30% complete starting from the locations where shallow flooding is expected, and designing is underway for entrances and other openings expected to be submerged or otherwise suffer deep flooding, which account for roughly 35% of locations. Thus, design and construction is progressing at roughly 65% of all locations. However, although doors performed well on pressure tests in factories, we are facing several problems during construction which shows unstableness in water stopping performance such as difficulty in maintaining level precision during installation on site, forming incomplete water stop lines with existing structures, etc. In light of the above, we will devote additional energy to further research to improve precision during installation. Acknowledgments Various manufacturers helped immensely with the development of flood preventing facilities. We would like to take this opportunity to express our gratitude and earnest hopes for their continued cooperation. Taihou Kinzoku Co., Ltd.: Horizontal bi-fold two-level water stop doors (Figure 9), counterpressure waterproofing doors (Figure 13), horizontal bi-fold waterproofing doors (Figure 14), positive-pressure hinged double doors (Figure 20), Sanwa Shutter Corporation: Waterproofing shutters (Figure 11) Ironworks Une Co., Ltd./Kumahira Co. Ltd.: Counterpressure sliding doors (Figure 18) Sumikei-Nikkei Engineering Co., Ltd./Tsubakimoto Machinery Co., Ltd.: Vertical waterproofing doors (Figure 15) References [1] Information on http://www.bousai.go.jp/kaigirep/chuobou/senmon/daikibosuigai/pdf/100402_shiryo_2.pdf Report on Expert Study of Major Flood Control Measures: Measures to Take to Lessen Submersion and Damage in Tokyo. [2] Information on http://www.kensetsu.metro.tokyo.jp/suigai_taisaku/yosouzu/kanda.pdf Map of expected inundation zone in the Kandagawa River watershed from the Metropolitan Tokyo Disaster Prevention website (referenced 9/26/2014).
ScienceDirect Procedia Engineering 165 (2016) 2 – 10
15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development”
Anti-inundation measures for underground stations of Tokyo Metro Yoji Aokia,*, Atsushi Yoshizawaa, Tomoya Taminatoa a
Tokyo Metro .Co. Ltd, 3-19-6, Higashi-ueno, Taito-ku, Tokyo, Japan
Abstract Tokyo Metro Co., Ltd. (hereinafter, Tokyo Metro) comprises nine lines operating over 195.1 km and 179 stations, and is used by 7.07 million passengers per day. Tokyo Metro operates on the belief that security equals safety plus service. In regard to safety, special effort is devoted toward countermeasures for natural disasters. In light of recent extreme weather events, countermeasures for heavy rains are particularly important. It was reported in the updated expectations for flood damage published in 2009 that metropolitan area’s 17 lines and 97 stations and 147km of the tunnels will be completely submerged underwater. In response to expectations, we are developing and installing various waterproofing facilities at all tunnel entrances, ventilation openings, underground station entrances and other openings. Among these, underground station entrances are expected to suffer the most damage. Most Tokyo Metro station entrances are situated on sidewalks, there are many obvious spatial restrictions. In light of these restrictions, conventional waterproofing doors (hinged doors that apply positive pressure against floodwater pressure) cannot be used to improve all entrances, thus we have continued to develop counterpressure doors, hinged double doors, shutters, bi-fold doors and other types of waterproofing doors that fit the environments of individual entrances. In addition, few of the many buildings to which Tokyo Metro tunnels connect underground are prepared for the updated expectations for flood damage, meaning that Tokyo Metro must take action on its own property to prevent flood water inundation from such buildings. This means taking flood control measures in underground concourses with severe spatial limitations. Thus, we have developed counterpressure sliding doors capable of withstanding water pressure from flooding up to 15 m deep. This report describes updated expectations for floods, Tokyo Metro’s improvement policy and descriptions of various types of underground waterproofing doors and the performance required of them. 2016Published The Authors. Published by Elsevier ©2016 © by Elsevier Ltd. This is an openLtd. access article under the CC BY-NC-ND license Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under theSustainable scientific committee of the 15th International scientific conference “Underground Urbanisation as a Urbanisation as aresponsibility Prerequisiteoffor Development. Prerequisite for Sustainable Development Keywords: Underground Station, Subway, Flood Control, developed.
* Corresponding author. Tel.: +81-33-837-7195 E-mail address: [email protected]
1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development
doi:10.1016/j.proeng.2016.11.730
3
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
1. Introduction Tunnels stretch across 168.6 km (158 stations) of Tokyo Metro subway lines, and roughly 90% of this total length is underground. Recently published updated flood expectations predict major damage to the entire metropolis of Tokyo due to water flowing into tunnel entrances and other openings turning the tunnels into wastewater pipes. Most concerning is water flooding into entrances, and a pressing challenge is to find flood control measures for both Tokyo Metro entrances as well as those from adjacent buildings (“petition entrances”). Our assumptions are based on a tsunami simulation for the Tokyo Metropolitan area, in the case of a vertical shock earthquake (Tokyo Bay northern earthquake M7.3) and a trench type earthquake (Genroku type Kanto earthquake M8.2 and Nankai-trough earthquake M9). These simulations assume that a tsunami would not breach the existing Tokyo Bay embankment. 2. Existing Tokyo Metro Flood Control Measures As measures against the flooding of roads by overflowing rivers, typhoons or sudden rains, Tokyo Metro has long installed water stop plates (Figure 1 shows one that is 750 mm tall) at entrances and flood preventing machines (Figure 2 show one that works for flooding up to 2 m) at ventilation openings in lowlands and depressions, as well as watertight gates (Figure 3) at some tunnel openings near lowlands and rivers. We have installed tide gates (Figure 4 shows a positive-pressure waterproofing door) at station entrances as a measure against storm surges in sea-level areas. In addition to these flood control measures, sump pumps discharge rainwater and other water that flows into tunnels.
Fig. 1. Water Stop Plate.
Fig. 2. Flood Fig.
Fig. 3. Watertight Gate.
Fig. 4. Outward Waterproofing Door.
3. Updated Expectations for Damage of Major flooding (collapse of levees on the Arakawa/Tonegawa Rivers) In January 2009, the Central Disaster Management Council (a Japanese cabinet committee) published a report of expected damage, in the event of a collapse of the Arakawa River levees. There are 2 scenarios, first with heavy rain that could be expected to occur once in 200 years (550 mm3 per day) and second with severely heavy rain expected to occur once in 1,000 years (638 mm3 per day). These predictions showed flood damage reaching central Tokyo and submerging most subway stations. Specifically, 17 lines, 97 stations and 147 km of tunnels in Tokyo would flood, and floodwaters would inundate central Tokyo around three hours after a levee collapse, putting Otemachi Station under as much as 1.8m of water (hereinafter Major flood). Figure 5-1 is a simulation of flooding 72 hours after the collapse of an Arakawa River levee in the 1,000-year case. In addition, heavy rain in the Tokai region (September 2000, 534 mm3 in 24 hours) prompted city administrators to publish hazard maps that expected depth of inundation in depressions due to the overflow of small and mediumsized rivers during sudden rains and other flood events(Figure5-2). (hereinafter Urban flooding).
4
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10 Fig.5-1. Expected Inundation Zone 72 Hours After Arakawa River Levee Collapse.
Arakawa River Point of collapse Nanboku line of Tokyo metoro Chiyoda line of Tokyo metoro
Above-ground inundation depth ■㻌 0.2-0.5 m ■㻌 0.5-1.0 m ■㻌 1.0-2.0 m ■㻌 2.0-5.0 m Below-ground inundation ■ Tunnels completely full ■ At least 2 m ■ At least 5 cm □ No inundation Hnzoumon line of Tokyo metoro
Yurakutyo line of Tokyo metoro Tozai line of Tokyo metoro Marunouchi line of Tokyo metoro Ginza line of Tokyo metoro Hibiya line of Tokyo metoro Central Tokyo
Source: Simulation of flooding in subways,etc., Japanese cabinet
Figure 5-2: Chiyoda City Expected Inundation Zone
Inundation Depth ■ 0.2-0.5 m ■㻌 0.5-1.0 m ■㻌 1.0-2.0 m ■㻌 2.0-5.0 m
Inundation area due to river overflow Chiyoda City Inundation area due to sudden rain
Source: Chiyoda City Flood Evacuation Map (flooding hazard map)
5
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
4. A New Direction for Flood Control Measures Tokyo Metro’s utmost priority is the preservation of human life. We are determined to take action against urban floods and major 1,000-year floods and seal all openings leading to tunnels to reduce damage and expedite the rehabilitation of underground spaces after flooding. We will also undertake flood control measures for aboveground facilities that must be promptly rehabilitated, such as transformers and signal transmission equipment housing (Figure 6). There are 612 facilities which connot cope with the current inundation predictions. Specifically, 473 facilities at station entrances, 102 facilities at ventilation openings, 5 facilities at tunnel entrances and several others (Table 1). A total investment of 20 billion yen and 10 years starting in 2013 have been budgeted for these improvement plans. Petitioner entrance Tokyo Metro Ventilation entrance tower
Office Bicycle parking
Above-ground station Station office
Ventilation opening
Entrance to tunnel
Signal transmission
Connecting entrance
Station office
concouse
Transformer room
Equipment Electric l room room Elec
Water stop point shows location of flood control ৌੁ measures ਜ਼઼॑ घ
Platform
Fig. 6. Tokyo Metro Flood Control Measures. Table 1. The inundation mesures point (at 2013).
Flood control measures Total
stations
Subway
Item
Not needed*
Needed
Tokyo Metro
608
360
248
Petitioners
331
167
164
20
61
Other businesses 81 Emergency exits
24
16
4
Above-ground stations
53
25
28
Total
1093 588
Flood preventing machines 959
857
505 102
6
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
Entrances to tunnels
20
15
5
5. The Surrounding Environment in Relation to Flood Control Most Tokyo Metro station entrances are placed on sidewalks, which means there are spatial limitations - extra sidewalk space cannot be secured or restrictions on the minimum clearance outline on the road side exists. Thus, some entrances cannot be improved with positive-pressure swing doors (Figure 4) that are already developed. In addition, the condition of petitioner entrances is such that very few building owners have already completed or plan to undertake measures against 1,000-year floods, but many building owners are rather concerned that water from tunnels will inundate the buildings. Because rainwater flows into stations from petitioner buildings when urban floods and major floods occur, the only option is to undertake flood control measures onTokyo Metro property. Thus, it is assumed that flood water inundation of the underground concourse could reach a depth of up to 10 to 15 m. 6. Flood Control Facilities in Stations When developing flood control facilities there is a requirement to set an allowable leakage volume, but currently the only exisiting standards were set by the Old Ministry of Posts and Telecommunications (0.02 m 3/m2h). Thus, each manufacturer sets its own standards. Power companies and others like them have set standards below 0.02 m3/m2h, and Tokyo Metro followed suit. However, leaks of 0.02 m3/m2h at all inundation points (over 500 in all) during a major flood would submerge over 300m of tunnel beneath 1.5 meters of water. Therefore, we have been aiming for absolutely no leakage at all as we progress in development with manufacturers. Station personnel will operate the facilities during disasters, so we considered the following points during development: the ease of operation regardless of age or gender and the possibility of manual operation during power outages. Because station personnel will eventually evacuate the stations themselves, waterproofing doors will need to be opened and closed from both the inside and outside. In addition, since most entrances cannot be expanded, we developed waterproofing doors that should fit within the existing entrance areas as much as possible. 6.1. Water stop plates (for flooding less than 1 m) We decided to use conventional water stop plates (Figure 7) to control flooding less than 1 m deep, but they weigh 12 kg each, making them difficult to carry up stairs. Thus, we switched the material from steel to aluminum to reduce the weight to roughly 6 kg. Note that water stop plates are initially set at the first lowest level (around 35cm tall as in Figure 8) to ensure that passengers can evacuate during the early stages of flooding.
Fig. 7. Water Stop Plate (up to 1 m).
Fig. 8. Water Stop Plate at the First Level
7
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
6.2. Horizontal Bi-Fold Two-Level Water Stop Doors (for flooding less than 1.5 m) Water stop doors are installed where flooding exceeds 1 m, but some existing sidewalk entrances require significant expansion but approval cannot be gained for sufficient expansion due to reasons such as traffic flow on sidewalks and intersection visibility (Figure 9). Thus, we developed bi-fold water stop doors set to function of evacation during the early stages of flooding (Figure 10). This reduces the expansion of occupation area required and enabled the improvement of this type of entrance. The development of these facilities resulted in the successful cutoff of nearly all leakage. Water stop door New wall (expanded area)
Water stop plate
Fig. 9. Entrance with Insufficient Space.
Fig. 10. Bi-fold Water Stop Door.
6.3. Waterproofing Shutters (for flooding less than 2.0 m) When flooding exceeds 1.5m, side horizontal bi-fold water stop doors lose their ability to withstand water pressure at their folds. Thus, we decided to use positive-pressure waterproofing doors (Figure 4), but as explained previously, in some cases due to the problem of the road control, we could not gain approval for sufficient expansion. In other cases installing a waterproofing door and Access Control Shutters would make the entrance too large. In addition to these design problems, these factors negatively affect visibility of nearby buildings insome cases, making it difficult to gain the understanding of localresidents.In light of limit the sizes of entrances to their original dimensions, we developed waterproofing shutters that can be used as Access Control Shutters (Figure 11). The slats are designed in a panel figure, and electric cylinders are used to act pressure on the slats horizontal and vertical direction for creating water stop lines (Figure 12). These shutters have the capacity to stop roughly 2 liters/m2h of water.
㻮 㻭
Fig. 11. Waterproofing Shutter.
Fig. 12. Waterproof Mechanism.
6.4. Counterpressure waterproofing doors (for flooding of 2.0 m) Waterproofing shutters stand around 500 mm taller than normal shutter boxes, and their housing above sidewalk entrances in front of stores negatively affect visibility. Therefore, it is sometimes impossible to gain the understanding of local residents. Thus, Tokyo Metro developed counterpressure waterproofing doors (Figure13),
8
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
which were widely reported by various media outlets as they were the first waterproofing facilities of our genuine flood control effort. We tested these doors for leaks using high-pressure jets and confirmed that there were no leaks.
Fig. 13. Counterpressure Waterproofing Door.
6.5. Horizontal Bi-fold Waterproofing Doors (to prevent submersion) Positive-pressure swing doors (Figure 4), waterproofing shutters (Figure 11) and counterpressure waterproofing doors (Figure 13) cannot be installed at building entrances because there is not much space between stairs and the edges of roads, ceilings are not high enough and the entrances themselves are wide. Thus, we developed positivepressure horizontal bi-fold waterproofing doors (Figure 14). These doors have the capacity to stop roughly 1 liter/m2h of water.
Fig. 14. Horizontal Bi-fold Waterproofing Door.
6.6. Vertical Bi-fold Waterproofing Doors (to prevent submersion) Waterproofing shutters and counterpressure waterproofing doors cannot withstand flooding over 2 m and thus cannot be installed at entrances expected to become submerged. Using only positive-pressure waterproofing doors (Figure 4) is possible, but as explained previously it is difficult to obtain approval to occupy roads, there are design problems and it is difficult to gain the understanding from local residents due to reducing visibility. Thus, we developed vertical bi-fold waterproofing doors (Figure 15). They are stored into the roof, and they are equipped with a feature that enables their use as electric maintenance shutters during normal operations (Figure 16). The motors are completely protected from water and can open and close the doors when entrances on the sidewalks are submerged. It is also possible to open and close the doors manually if the power supply is cut off. These doors have the capacity to stop roughly 1 liter/m2h of water.
Yoji Aoki et al. / Procedia Engineering 165 (2016) 2 – 10
Fig. 15. Vertical Bi-fold Waterproofing Door.
Fig. 16. Overhead Door.
6.7. Counterpressure Waterproofing Sliding DoorsˋHinged Counterpressure Waterproofing Double Doors Flood control measures at petitioner entrances are for expected flooding at a depth of 10 to 15 m, because they have to be undertaken within Tokyo Metro property, namrly within our subway concourse. Highly reliable and affordable positive-pressure waterproofing doors (Figure 4) have been used because many petitioner buildings are connected to Tokyo Metro properties by passageways that are quite narrow. On the other hand , some petitioner entrances have no passageway between the buildings and stations (Figure 17). To counter this, we developed counterpressure waterproofing sliding doors (Figure 18) that make it possible to undertake flood control measures from petitioner entrances. However, the sliding door’s pocket may not be installed because there is unmovable room(Figure 19)(ex: electric room). There for, we developed hinged counterpressure waterproofing double doors capable of withstanding flooding up to a depth of 15 m (Figure 20). These doors are nearly watertight, but the utmost care is required to position the door frames because a strong pull-out force acts on the existing structure.
Fig. 17. Petitioner Entrance with no passageway.
The machine which is impossible of transferencee ↓ Sliding door’s pocket is impossible of setting
concourse
Fig. 18. Counterpressure Sliding Door.
Petitioner entrances
Counterpressure Double Door is possible
Fig. 19. Petitioner Entrance with no Sliding door’s pocket.
Fig. 20. Hinged Counterpressure Waterproofing Double Doors.
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7. Conclusion As explained above, the development stage is approaching its end, and we have entered to the design and construction stages. Construction is roughly 30% complete starting from the locations where shallow flooding is expected, and designing is underway for entrances and other openings expected to be submerged or otherwise suffer deep flooding, which account for roughly 35% of locations. Thus, design and construction is progressing at roughly 65% of all locations. However, although doors performed well on pressure tests in factories, we are facing several problems during construction which shows unstableness in water stopping performance such as difficulty in maintaining level precision during installation on site, forming incomplete water stop lines with existing structures, etc. In light of the above, we will devote additional energy to further research to improve precision during installation. Acknowledgments Various manufacturers helped immensely with the development of flood preventing facilities. We would like to take this opportunity to express our gratitude and earnest hopes for their continued cooperation. Taihou Kinzoku Co., Ltd.: Horizontal bi-fold two-level water stop doors (Figure 9), counterpressure waterproofing doors (Figure 13), horizontal bi-fold waterproofing doors (Figure 14), positive-pressure hinged double doors (Figure 20), Sanwa Shutter Corporation: Waterproofing shutters (Figure 11) Ironworks Une Co., Ltd./Kumahira Co. Ltd.: Counterpressure sliding doors (Figure 18) Sumikei-Nikkei Engineering Co., Ltd./Tsubakimoto Machinery Co., Ltd.: Vertical waterproofing doors (Figure 15) References [1] Information on http://www.bousai.go.jp/kaigirep/chuobou/senmon/daikibosuigai/pdf/100402_shiryo_2.pdf Report on Expert Study of Major Flood Control Measures: Measures to Take to Lessen Submersion and Damage in Tokyo. [2] Information on http://www.kensetsu.metro.tokyo.jp/suigai_taisaku/yosouzu/kanda.pdf Map of expected inundation zone in the Kandagawa River watershed from the Metropolitan Tokyo Disaster Prevention website (referenced 9/26/2014).