Safety Factors in Construction and Ventilation, Wawona Vehicular Tunnel, Yosemite National Park, California Page: III
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CONTENTS
Page
Part I.-Construction of tunnel_ -__ _ __ ----------- 1
Introduction------------------------------------------ 1
Acknowledgments 1-------------------------------------------- 1
Organization_ 2------------------------------------------------ 2
Cost of construction---_------------------------------------- 2
Operating specifications for construction of Wawona Tunnel------- 2
Size of operation_------------------------------------- 5
Design of tunnel 6----------------------------------------- 6
Surface plant and equipment_______--- --------------------- 6
Underground equipment and haulage------------------- 7
Drilling and blasting__--------------------------------- 8
Ventilation and gas_ 10
Supervision, general safety practices, and accident prevention___ 12
Industrial insurance and medical service---------- ---------- 12
Concrete lining and paving -__ ___------------------- 13
Accident experience and costs----------------------------- 14
Discussion of accident occurrence and costs ------------------ 17
Part II.-Ventilation of Wawona Tunnel for public use _ 19
Basis of ventilation ------------------------------------------20
Ventilation system--------------------------------------- ---22
Effect of size of ventilating adit on ventilating problem ------------- 23
Vehicular traffic --------------------------------------------25
Natural ventilation_ 25
Fan equipment --------------------------------- 26
Fan operation under traffic conditions---------------------- 28
Power supply and automatic control -----------------------------29
Carbon monoxide analyzers and recorders -------------------------32
Lighting system --------------------------------------------33
Safety features------- -------------------- --------------- 33
ILLUSTRATIONS
Fig.
1. Cost segregations, Wawona Tunnel, Yosemite National Park------- 3
2. Tunnel and gallery sections, Wawona Tunnel--------------------- 6
3. View of tunnel location--6-----
4. Surface plant at time of construction at east portal_ _ _ _ _ 7
5. Storage-battery locomotive and loading bins for muck storage and
distribution7---------------------------------------------- 7
6. Track arrangements underground in main-line section------------- 8
7. Track arrangement in face region_-_____ - --_______-_______- 8
8. Drilling set-up with curved bars for supporting drills for side and
bench drilling--------------------------------------------- 9
9. Drilling set-up for drilling from main horizontal bars-------------- 9
10. Preliminary wiring for lighting and blasting ---------------------- 10
11. Track arrangements at portal, with Root positive-pressure blower
set-up --- ------- ----- ----------- 11
12. A, Root positive-pressure blower set-up; B, track arrangements at
portal----------------- ---------------------------------10
13. Natural draft, Wawona Tunnel_____________________________ _ 27
14. Ventilating fans, Wawona Tunnel___________ --___________-_ 28
15. Graph of travel and carbon monoxide content in tunnel, June 10 and
11, 1933_ __ _ 29
16. Ventilating fans looking from fan adit toward main bore ----------- 32
17. Switchboard and automatic-control panels at fan control room --. 32
18. Carbon monoxide control analyzers_-------------------------_ 32
19. Lighting effect with all lamps burning --------------------------- 33
20. Tunnel lights with half the lamps in operation _ _ _ 33
21. Semaphore in warning position at west (upper) portal_ 33
]II
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Ash, S. H. Safety Factors in Construction and Ventilation, Wawona Vehicular Tunnel, Yosemite National Park, California, report, 1940; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc66427/m1/3/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.