This top page is to transmit the proof that I am still alive and enjoying retired life, mainly to my relatives, friends and former students. A story or an event is selected from daily life and my thoughts and experience are introduced.
From Daily Life - 83: Tunnel ventilation During traveling by train or car, we often pass through tunnels. Unless
the tunnel is very long, we pass through it almost unconsciously. My longtime
friend, Mr. N, founded a company specialized in ventilation and safety equipment for automobile
tunnels and celebrated its 25th anniversary this year. I was invited to the anniversary
event to give a congratulatory speech, and it reminded me of my 40 years
of commitment to the planning of major automobile tunnels in Japan. On
this occasion, I introduce herewith briefly what tunnel ventilation is.
With the advancement of railway electrification, railway tunnels with
ventilation equipment are rare, except for subways. In the case of the
longest railway tunnel in Japan, Seikan Tunnel (54 km), fresh air is supplied
from two inclined shafts to its center to regulate the internal temperature
and allow safe evacuation in the event of a fire. This is a special case
because of its length and undersea condition.
In automobile tunnels, ventilation must always be considered because it
is necessary to dilute the pollutants emitted by engines (harmful gases
such as carbon monoxide and nitrogen oxides and diesel soot) under the
permissible limit. Harmful gases are toxic to the health of pedestrians
through breathing, and diesel soot poses a risk to drivers by reducing
visibility.
Pollutants emitted inside a tunnel are carried to the outside by natural
wind due to the difference in atmospheric pressure between the portals,
traffic wind pushed by running automobiles, and diffusion caused by strong
air turbulence generated by cars passing by. If these effects are strong
enough, mechanical ventilation is not necessary. Most of short tunnels
under 500 meters fall into this category.
When a construction plan for an automobile tunnel over 500 meters is decided,
the need for ventilation and safety equipment is determined, taking into
account the traffic volume, one- or two-way, terrain conditions, and environmental
regulations near the portals.
In the past, automobiles were a major source of public nuisance. However,
due to successive tightening of exhaust gas regulations, the emission of
pollutants from both gasoline and diesel vehicles has decreased dramatically
in recent years. As electric vehicles become more widespread, the emission
of pollutants will decrease even further. For this reason, tunnel ventilation
facilities are often installed not for diluting pollutants but to ensure
the airflow necessary for safe evacuation in the event of a fire. Recently,
we see many tunnels with jet fans installed on the ceiling (photo upper
right), but it is rare to see fans that are in operation.
Ventilation fans are regularly in operation in long tunnels such as Kan'etsu
Tunnel (11 km, photo upper left), Enasan Tunnel (7 km), and Tokyo Bay Aqua
Tunnel (10 km). In the past, long tunnels were mostly mountain tunnels.
However, as construction of underground expressways in urban areas progresses,
they become the record holder of the longest automobile tunnel. Currently,
Yamate Tunnel (19 km) on the Metropolitan Expressway holds the record.
Automobile tunnels have become more familiar as they feel like subways.
Automobile tunnels have a history of serious accidents that have cost lives, such as the fire at Nihonzaka Tunnel and the ceiling panel collapse at Sasago Tunnel. I hope that the ventilation and safety equipment of automobile tunnels will keep assuring the safety of passersby for years to come.
→ Past Top Pages
"From Daily Life"
1: Tracing family roots
2: The second last car
3: August 15. my memorial day
4: Battlefield rations
5: Begginer at the gym
6: Fuji View Hotel
7: Lesson in Hiragana writing by brush
8: Moving from old to new smartphone
9: Living alone in my second year
10: Welcomed by cherry blossom
11: Eden of peach blossom
12: Tama River Walk
13: Chichibu Pilgrimage
14: Bonds with local community
15: About my homepage
16: Annual report of athletic gym
17: Pilgrimage to Mt. Tsukuba
18: Reunion of alumni and classmates
19: Braking by left foot
20: Battlefield rations in the sequel
21: Granddaughter has come!
22: Visit to Kobayashi Residence
23: Wake-up exercise
24: Digital photo album
25: Seven tools for brushing teeth
26: Ambulance
27: Quick report on drive monitoring
28: Hearing aid
29: Jindai Botanical Park
30: 2020, a historic year
31: Topics of eye
32: Final report on drive monitoring
33: Cognitive ability test
34: PCI to prevent heart infarction
35: Ashikaga Flower Park
36: 90 years old supported by medication
37: 3 years with Subaru
38: 45 years living in Seijo
39: Caspian Sea yogurt
40: Home Museum of Aunt Zschäbitz
41: Reunion of university classmates
42: Okutama spar tour
43: New Year's greeting card
44: Implant
45: Fuchu Forest Park
46: Grave closing
47: Walking group of local community
48: How-to books for the elderly
49: Home altar
50: Such a life
51: Knee of the elderly
52: Metropolitan Kinuta Park
53: Shirakaba Art Museum of Kiyoharu
54: Haiku; Metasequoia
55: Three years with COVID-19
56: Battlefield rations in the 6th year
57: Hearing impairment
58: Shinjuku Station
59: Haiku with photograph
60: Moving to 5G smartphone
61: History of private cars
62: Setagaya Art Museum
63: FreeCell
64: Turbo
65: Hinata Temple of Yakushi
66: Moving of home computer
67: Amakusa tour
68: Hand craft as a hobby
69: Kitami Community Square
70: Photo-Haiku 2
71: Support scam abusing Trojan Horse
72: Bedside gym
73: Metropolitan Nogawa Park
74: Family funeral
75: Sudoku (Number Place)
76: Photo-Haiku 3
77: Ohyama Afri Shrine
78: Kunisaki Peninsula tour
79: The old school system is far away
80: Cooking group of local community
81: Motor fan group of local community
82: Directories disappear!
"Memorable Scenes"
Series 1: Parade with Doctor hat on the head
Series 2: Calligraphy in a frame
Series 3: A young man from the Orient
Series 4: Sumo-stamping
Series 5: Waiting room of Shanghai Station
Series 6: Let's Walk Festival
Series 7: Last long-distance drive
Series 8: My Car No. 3
Series 9: Ski camp
Series 10: Safari experience
Series 11: First encounter with dogwood
Series 12: Mt. Fuji
"Treasure Box of Words"
Series 1: Virtue brings profit
Series 2: Wait for a ripe moment
Series 3: Catch the symptoms
Series 4: Words are selected metaphors
Series 5: Start with two humans
Series 6: Optimism is a will, pessimism a mood
Series 7: Atop a summit, and another becomes visible
Series 8: We see only what we want to see
Series 9: Chanllenge is the privilage of the young
Series 10: Today is the first day of my life
Engineer Series 1: Who's engineer, juveniles' answer
Series 2: Corus of "We raise engineers!"
Series 3: From Nobel Prize to Gold Medal
Series 4: Professionals in three categories
Series 5: Various tasks in engineering
Series 6: Classification of EPs by IEA
Series 7: Science, technology and related professionals
Series 8: Proposal for the classification of engineers
Series 9: Revised proposal for the classification of engineers
Series 1 - 10: Whole Series including summary and remarks
Cartoon Series 1: Mechanism of viscosity
Series 2: Mechanism of loss generation
Series 3: Commuter packer and enthalpy
Series 4: Skinny grasshopper and fat pupa
Series 5: From hand-drawn picture to ready-made clip art
Series 6: Why do you learn? - 1
Series 7: Why do you learn? - 2
Series 8: Two Sciences
Series 9: Scientist and Engineer
Series 10: Science and Non-science
Series 11: Structure of human relations
Series 12: Oriental subconsciousness
Nostalgia Series 1: The first own car
Series 2: The first driver's license
Series 3: Comparison of German and Japanese Diploma
Series 4: The first air travel
Series 5: Tachometer used 60 years ago
Series 6: The three sacred calculators
Series 7: The first home computer
Series 8: Sentimental journey to Nordkapp
Series 9: Change of photograph
Series 10: Story of passport
The others
Membership of Academic/Professional Societies
Curriculum Vitae
Recent Publications
The center of gravity of recent publications has been shifting from those with the topics in fluids engineering to those in engineering education. Please refer to Publications List of the recent papers written in English.