Chapter XXV

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THE COST OF TUNNEL EXCAVATION AND THE TIME REQUIRED FOR THE WORK.

=Cost.=--The cost of a tunnel will depend upon the cost of the two principal operations required in its construction, viz., the excavation of the cross section and the lining of the excavation with masonry, metal, or timber. These two operations may in turn be subdivided, in respect to expense, into cost of labor and cost of materials. It is a comparatively simple matter to calculate the cost of the building materials required to construct a tunnel; but it is very difficult to estimate with accuracy what the cost of labor will be. The reason for this is that it is impossible to foresee exactly what the conditions will be; the character of the material may change greatly as the work proceeds, increasing or decreasing the cost of excavation; water may be encountered in quantities which will materially increase the difficulties of the work, etc. Nevertheless, while accurate preliminary estimates of cost are not practicable, it is always desirable to attempt to obtain some idea of the probable expense of the work before beginning it, and the more usual means of getting at this point will be discussed here.

Two methods of estimating the cost of tunnel work are employed. The first is to calculate the probable expense of the various items of work, based upon the available data, per unit of length, and then add to this a margin of at least 10% to allow for contingencies; the second is to apply to the new work the unit cost of some previous tunnel built under substantially the same conditions. In the first method it is usual to consider the strutting and hauling as constituting a part of the work of excavation. To estimate the cost of excavation involves the consideration of three general items, viz., the excavation proper, the strutting of the walls of the excavation, and the hauling of the excavated materials and the materials of construction.

The cost of excavating the preliminary headings or drifts is greater per unit of material removed than that of excavating the enlargement of the section. The cost of bottom drifts is also always greater than that of top headings, the material penetrated remaining the same. Mr. Rziha gives the comparative unit costs of excavating drifts, headings, and enlargement of the profile as follows:--

Bottom drifts $9.20 per cu. yd.
Top headings 4.80 „ „ „
Enlargement of profile 2.84 „ „ „

The cost of hauling increases with the length of the tunnel. This fact and amount of this increase are indicated by the following actual prices for the Arlberg tunnel:--

Top heading $6.76 per cu. yd., increasing 37 cts. per mile
Bottom drift 7.40 „ „ „ „ 26 „ „ „
Enlargement of profile 2.70 „ „ „ „ 10 „ „ „

In all the prices given above, the cost of strutting and hauling is included in the cost of excavation.

The cost of excavation is not always the same for the same character of materials in different tunnels. The following figures show the prices paid for the excavation of calcareous rock in four different German tunnels:--

Berliner Nordhausen Wetzler R.R. $1.24 per cu. yd.
Ofen 1.30 „ „ „
Stafflach 2.76 „ „ „
Gries 1.92 „ „ „

The method of tunneling has little influence upon the cost of the work, as shown by the following figures from tunnels excavated through calcareous rock by different methods:--

Ofen tunnel Austrian method $93.19 per lin. ft.
Dorremberg tunnel Belgian method 86.08 „ „ „
Stafflach tunnel English method 91.69 „ „ „

The Martha and Merten tunnels, excavated through soft ground by the Austrian and German methods respectively, cost $87.95 and $87.55 per lin. ft. respectively. In the excavation of the various sections of the tunnel for the new Croton Aqueduct in America, the following prices were paid:--

Excavation of heading $8 to $10.00 per cu. yd.
Tunnel in soft ground 8 to 9.00 „ „ „
Tunnel in rock 7 to 8.50 „ „ „
Brick masonry 10.00 „ „ „
Timber in place $40 per M. ft. B. M.

It is the practice in America to include the work of hauling under excavation, but not to include the strutting, which is paid for separately. In some cases only the market price of the timber is paid for separately, the cost of setting up being included in the price of excavation. The writer prefers the European practice of including the total cost of timbering under excavation, since the two operations are so closely connected, and since the contractor employs the same timber over and over again. Knowing the dimensions of the several members of the strutting, it is a simple, although somewhat tedious,

process to calculate the total quantity required. An idea of the quantity of timber required for strutting in soft ground may be had from the data given on page 55. The quantity will decrease as the cohesion of the material penetrated increases, until it becomes so small in hard rock-tunnels as to cut very little figure in the total cost.

The cost of hoisting excavated materials through shafts depends upon the depth from which it is hoisted, and upon the character of hoisting apparatus employed. The following table, showing the cost of hoisting for different lifts and by different methods, is given by Rziha, the cost being in francs per cubic meter:--

+-------+----------+----------------------+-------------+
| HEIGHT| WINDLASS.| HORSE GINS. |STEAM HOISTS.|
| IN +----------+----------+-----------+-------------+
|METRES.| |ONE HORSE.|TWO HORSES.| |
| | Francs | Francs | Francs | Francs |
| |per Cu. M.|per Cu. M.| per Cu. M.| per Cu. M. |
+-------+----------+----------+-----------+-------------+
| 15 | 0.172 | 0.077 | 0.062 | 0.035 |
| 30 | 0.212 | 0.087 | 0.070 | 0.045 |
| 45 | 0.257 | 0.100 | 0.080 | 0.050 |
| 60 | 0.305 | 0.112 | 0.092 | 0.082 |
| 90 | 0.410 | 0.152 | 0.110 | 0.087 |
| 120 | 0.535 | 0.195 | 0.135 | 0.092 |
| 150 | 0.722 | 0.240 | 0.157 | 0.112 |
+-------+----------+----------+-----------+-------------+

Mr. Séjourné, a French engineer, who has been connected with the construction of numerous tunnels by the Belgian method where he was in position to secure comparative figures, has given the following rules for calculating the cost of tunnels. Assuming _A_ to represent the cost of excavating a cu. yd. in the open air, the cost of excavating the same quantity underground in driving headings will be from 9 _A_ to 11 _A_, and in enlarging the profile it will be about 5 _A_. The cost of constructing single-track tunnels varies with the thickness of the lining, and may be calculated by the following formulas:

Without lining, _C_ = 5.5 _A_.
With roof arch only, _C_ = 6.4 + 6.4 _A_.
With lining 18 in. thick, _C_ = 9.4 + 7 _A_.
With lining 2 ft. thick, _C_ = 11 + 8 _A_.

In these formulas _C_ is the cost per cu. yd. of excavation, including the masonry. For double-track tunnels the amounts given by the above formulas may be used by reducing them about 7¹⁄₂% or 8%.

The second method of estimating the cost of tunnel work consists in assuming as a unit the unit cost of tunnels previously excavated under similar conditions. Mr. La Dame gives the following unit prices for a number of tunnels driven through different materials:

+-------------------+--------+-------------+--------+----------------+
| NATURE OF SOIL. |TUNNELS,| EXCAV. PER |COST PER| MAX. AND MIN. |
| | NO. OF | CU. YD. |LIN. FT.| PER LIN. FT. |
+-------------------+--------+-------------+--------+----------------+
|Granite-gneiss | 56 |$3.07 @ $3.85| $100. |$61.46 @ $190.40|
|Schist | 39 | 1.38 @ 1.53| 75.42| 43.11 @ 70.68|
|Triassic | 3 | ... | 90.85| 84.75 @ 93.33|
|Jurassic | 69 | 1.23 @ 1.38| 77.86| 35.24 @ 157.2 |
|Cretaceous | 34 | 0.61 @ 0.77| 59.60| 27.37 @ 92.25|
|Tertiary and modern| 39 | 0.33 @ 0.61| 105.80| 51.52 @ 188.36|
+-------------------+--------+-------------+--------+----------------+

In the following table is given a list of tunnels excavated through different soils, from the most compact to very loose materials, and driven according to the various methods which have been illustrated.

DOUBLE-TRACK TUNNELS.

SINGLE-TRACK TUNNELS.

[16] Are unlined.

[17] Lined with timber.

The Habas tunnel through quicksand, between Dax and Ramoux, France, cost $118.50 per lin. ft. The cost of the Boston subway was $342.40 per lin. ft. The Severn and Mersey tunnels, constructed through rock under water, cost respectively $208.38 and $263 per lin. ft. The First Thames Tunnel, driven by Brunel’s shield, cost $1661.66 per lin. ft. The Hudson River and St. Clair River tunnels, excavated through soft ground by means of shields and compressed air, cost respectively $305 and $315 per lin. ft. The Blackwall double-track tunnel under the River Thames, which is the largest tunnel ever built by the shield system, cost $600 per lin. ft.

In making estimates of the cost of projected tunnel work based on the cost of tunnels previously constructed through similar materials, it is important to keep in mind the date and location of the work used as the basis for calculations. For example, a tunnel excavated in Italy, where labor is very cheap, will cost less than one excavated in America, where labor is dear, all other conditions being the same. Other reasons for variation in cost due to difference of date and location of construction will suggest themselves, and should be taken into full consideration in estimating the cost of the new work.

=Time.=--The time required to excavate a tunnel depends upon the character of the material penetrated and upon the method of work adopted. Tunnels driven through soft ground by hand require about the same time to construct as tunnels driven through hard rock by the aid of machinery. Tunnels can be driven through hard rock at about as great a speed as through soft or fissured rock, chiefly because the work of blasting is more efficient in hard rock, and because no time is required in timbering. The following table shows the average rate of progress in different parts of the tunnel excavation through both hard and soft materials in feet per month:--

+---------------+--------------------+--------------------+-----------+
| QUALITY | HEADING. | EXCAVATION |ENLARGEMENT|
| OF SOIL. | | OF SHAFTS. |OF PROFILE.|
| +----------+---------+---------+----------+-----------+
| | By hand. | By | By hand.| By | By hand. |
| | | machine.| | machine. | |
+---------------+----------+---------+---------+----------+-----------+
|Very loose soil|16.7- 26.8| | 6.6-16.7| | 6.6- 16.7|
|Loose soil |33.4-100 | |16.7-33.4| | 16.7- 33.4|
|Soft rock |66.8 |233.8-334|33.4-66.8|66.8-132.6| 33.4- 50 |
|Hard rock |50 - 66.8|233.8-334|33.4-50 |66.8-132.6| 66.8-100 |
|Very hard rock |33.4 |233.8-334|16.7-33.4|66.8-132.6| 66.8-100 |
+---------------+----------+---------+---------+----------+-----------+

The following tables showing the average rate of progress have been compiled from the actual records made in the tunnels named:

The following table shows the monthly progress of completed tunnel in feet excavated through rock:

The average monthly progress in feet of excavating tunnels through treacherous ground may be quite generally assumed to be for: (1) clay of the first variety from 43.4 ft. to 60 ft.; for clay of the second variety from 33.4 ft. to 43.4 ft.; for clay of the third variety from 23.3 ft. to 33.4 ft., and for quicksand from 30 ft. to 50 ft. The monthly progress in feet made in sinking the shafts of the Hoosac and Musconetcong tunnels in America was as follows:--

+---------------+------------+---------+--------+------------+
|NAME OF TUNNEL.| DIMENSIONS | DEPTH |PROGRESS|CHARACTER OF|
| | IN FEET. |IN FEET. |IN FEET.| MATERIAL. |
+---------------+------------+---------+--------+------------+
|Hoosac: | | | | |
| East shaft |15.4 × 27.7| 1035 | 21.7 |Mica schist.|
| West shaft | 8 × 16 | 267 | 16.7 |Gneiss. |
|Musconetcong: | | | | |
| Vertical shaft| 8.35 × 16.7| 113.5 | 100 |Loose rock. |
| Inclined shaft| 8.35 × 26 | 304. | 32 |Loose rock. |
+---------------+------------+---------+--------+------------+

The average monthly progress of sinking shafts in treacherous soils may be assumed to be as follows: clay of first variety, 50 ft. to 75 ft; clay of second variety, 36.75 to 50 ft; clay of third variety, 23.4 ft. to 36.75 ft; quicksand, 16.7 ft. to 33.4 ft.

For the reason that the details change with the various conditions encountered in every work, all the tunnel operations have been treated in a general way, purposely avoiding to give any detail. Also the rate of progress and items of cost of tunnels have been given in a broad manner because they greatly vary in the different works. This information, however, can be easily obtained by consulting the Engineering Magazines, where are reported all the tunnel works of America and Europe, and where are given so many details which are very valuable to expert engineers in charge of similar works, but not to students and people who are looking only for general knowledge.

INDEX

Accidents and Repairs in the Belgian Method, 152
Accidents in Tunnels:
After Construction, 308
Baltimore Belt Line, 165
Chattanooga Tunnel, 311
During Construction, 301
General Discussion, 301
Giovi Tunnel, 309
Repairing of, 304
Acetylene Gas Lighting, 334
Air Compressors, Description of, 87
Air Locks, 264-272
Air Pressure, 268
American Method:
General Description, 172
Excavation, 172
Strutting, 174
Hauling, 175
Arrangement of Drill Holes, 90
Artificial Ventilation, 327
Austrian Method of Tunneling:
Advantages and Disadvantages, 180
Excavation, 176
General Description, 176
Lining, 180
Strutting, 177
Average Progress in Tunnels, 342

Baltimore Belt Line Tunnel, General Description, 160
Barlow’s Shield, 242
Beach’s Shield, 246
Belgian Method:
Accidents and Repairs, 152
Advantages and Disadvantages, 152
Excavation, 145
General Description, 144
Lining, 148
Hauling, 150
Strutting, 146
Bench, 131
Bends, 268
Blackwall’s Tunnel Shield, 248
Blasting-cone, 33
Blickford Match, 31
Boston Subway:
General Descriptions, 203
Roof Shield, 251
Boulder Tunnel Relined, 315
Box-cars, 61
Box Strutting, 51
Brandt Drilling Machine, 28, 112
Brown, W. L., 269
Brunel’s Shield, 240

Caissons, 293
Canals and Pipe Lines, 86
Cascade Tunnel, 98
Center-cut, 91
Center Line:
Curvilinear Tunnels, 14
Determination of, 9
Rectilinear Tunnels, 9
Simplon Tunnel, 106
Submarine Tunnels, 265
Triangulation, 12
Transferred through Center Shafts, 13
Transferred through Side Shafts, 14
Value’s Device, 10
Centers:
For Arches, 68
English Method, 169
Ground Molds, 66
Italian Method, 184
Lagging, 71
Leading Frames, 67
Setting Up, 70
Striking, 71
Chattanooga Tunnel, Accident, 311
City and South London Railway Shield, 250
Classification of Tunnels, 42
Coal-gas Lighting, 333
Cofferdam Method of Tunneling, 281
Van Buren Street Tunnel, Chicago, 282
Collapse of Tunnels, 302
Compressed Air:
For Power, 87
For Ventilation, 330
Concrete Lining, 75
Fort George Tunnel, 139
Murray Hill Tunnel, 126
Cost of:
Double-track Tunnels, 340
Hauling, 338
Headings, 337
Hoisting, 338
Single-track Tunnel, 340
Submarine Tunnels, 341
Subways, 209-217
Tunnels, 336
Craven, Alfred, 39
Craven’s Sunflower, 39
Cross-section:
Dimensions of, 20
Form of, 18
Hudson River Tunnel Pennsylvania Railroad, 277
Crown-bar (see American Method).
Subways, 204-211
Croton Aqueduct Tunnel, 95
Culverts, 80

Detroit River Tunnel, 296
Diamond Drilling Machine, 27
Directing the Shield, 265
Drift, 37
Drift Method:
General Discussion, 102
Murray Hill Tunnel, 123
Simplon Tunnel, 103
Drilling Machines:
Brandt, 112
Ingersoll, 26
Drills:
Diamond, 27
Hand, 23
Mountings for, 25
Percussion, 24
Power, 24
Rotary, 27
Dumping Cars, 60

Electric Firing, 32
Electric Lighting, 335
English Method:
Advantages and Disadvantages, 171
Centers, 169
Excavation, 166
General Discussion, 166
Lining, 170
Strutting, 167
Enlargement of the Profile, 38
Entrances, 81
Erector, 272
Excavation:
American Method, 172
Arrangement of Drill Holes, 90
Austrian Method, 176
Belgian Method, 145
Center-cut, 91
Enlargement of Profile, 38
English Method, 166
Fort George Tunnel, 136
German Method, 155
Headings, 37, 91
Hudson River Tunnel of Pennsylvania Railroad, 273
Italian Method, 182
Murray Hill Tunnel, 124
Quicksand Method, 189
Pilot Method, 193
Shield and Compressed Air Method, 267
Simplon Tunnel, 110
Excavating Machines:
For Earth, 22
For Rock, 23
Explosions, 33
Dynamite, 30
Gunpowder, 28
Nitroglycerine, 29
Quantity of, 34
Storage of, 30

Failure of Tunnel Roof, 305
Forgie, James, 269
Fort George Tunnel, 135
Foundations for Lining, 76
Fox, Charles B., 103
Frame Strutting, 49
Fuses, 31

Geological Survey, 3
German Method:
Advantages and Disadvantages, 159
Excavation, 155
General Description, 155
Hauling, 158
Strutting, 156
Giovi Tunnel Accident, 309
Graveholz Tunnel, 98
Greathead’s Shield, 245

Hand Drills, 23
Harlem River Tunnel, 285
Hauling:
American Method, 175
Belgian Method, 150
Italian Method, 185
German Method, 158
Hudson River Tunnel of Pennsylvania Railroad, 278
Motive Power, 61
By Way of Entrances, 59
Simplon Tunnel, 111
By Way of Shafts, 62
Heading and Bench Method:
Fort George Tunnel, 135
General Discussion, 130
St. Gothard Tunnel, 1
Headings, 37, 91
Hewett, H. B., 269
History of Tunnels, xiii
Hoisting Machines:
General Discussion, 62
Elevators, 64
Horse Gins, 63
Windlass, 63
Hoosac Tunnel, 93
Hopkins, Stephen W., 135
Hudson River Tunnel of Pennsylvania Railroad, 269
Hydraulic Jacks, 260, 271
Hydraulic Rams, 271

Illumination:
Acetylene Gas, 334
Coal-gas, 333
Electric, 335
Hudson River Tunnel of Pennsylvania Railroad, 280
Lamps and Lanterns, 330
Inclination of Strata, 6
Ingersoll Drilling Machine, 26
Inverted Arch Lining, 77
Iron and Masonry Lining, 74
Iron Lining, 73, 261, 276
Iron Strutting, 55
Full Section, 56
Headings, 56
Shafts, 57
Italian Method:
Advantages and Disadvantages, 188
Excavation, 182
General Description, 182
Modifications, 186
Strutting, 183

Jacks, 260, 271
Joining the Caissons, 295

Lagging, 71
Lamps and Lanterns, 330
Lighting (see Illumination).
Lining:
Austrian Method, 180
Belgian Method, 148
Concrete, 126, 139
English Method, 170
Foundations, 76
General Observations, 78
German Method, 158
Hudson River Tunnel Pennsylvania Railroad, 276
Invert, 77
Iron, 73, 261, 276
Iron and Masonry, 74
Italian Method, 185
Masonry, 74
Quicksand Method, 191
Roof Arch, 77
Side Tunnels, 79, 83
Side Walls, 77
Subways, 207-213
Timber, 72
Thickness of Masonry, 78, 83
Little Tom Tunnel Relined, 321
Loose Soil (see Soft Ground).

Masonry (see Centers).
Masonry Culverts, 80
Masonry (see Lining).
Masonry Lining, 74
Masonry Niches, 81
McBean, Daniel, 285
Mechanical Installations for Tunnel Work, 84
Milwaukee Tunnel, 226
Mont Cenis Tunnel, 92
Monthly Progress of Tunnels, 342
Mullan Tunnel Relined, 319
Murray Hill Tunnel, 123

Natural Ventilation, 326
New York Rapid Transit Subway, 209
Niagara Falls Power Tunnel, 97
Niches, 81

Open Cut or Tunnel, 1
Open-cut Tunneling:
General Discussion, 195
Parallel Longitudinal Trenches, 197
Single Trench, 196
Single Narrow Trench, 197
Transverse Trenches, 200
Tunnels on the Surface, 200

Palisade Tunnel, 94
Pennsylvania Railroad Shield, 270
Percussion Drills, 24
Pilot Method of Tunneling, 192
Plank Centers, 69
Platform Cars, 59
Plenum Method of Ventilation, 329
Pneumatic Caissons, 287
Polar Protractor, 39
Portals, 81
Power Drills, 24
Power Plants:
Air Compressors, 87
Canals and Pipe Lines, 86
Cascade Tunnel, 98
Croton Aqueduct Tunnel, 95
General Description, 84
Graveholz Tunnel, 98
Hoosac Tunnel, 93
Hudson River Tunnel Pennsylvania Railroad, 279
Mont Cenis Tunnel, 92
Murray Hill Tunnel, 128
Niagara Falls Power Tunnel, 97
Palisades Tunnel, 94
Receivers, 89
Reservoirs, 86
Simplon Tunnel, 117
Sonnstein Tunnel, 99
St. Clair River Tunnel, 99
St. Gothard Tunnel, 133
Steam, 85
Strickler Tunnel, 96
Turbines, 86
Prelini’s Shield, 251
Presence of Water, 7
Prevention of Collapse, 303
Progress in Sinking Shafts, 343
Progress of Excavation, 342
Progress of the Work, 342
Progress in Simplon Tunnel, 122

Quantity of Air for Ventilation, 331
Quicksand Tunneling:
General Discussion, 188
Removing the Seepage Water, 191
Quantity of Timber in Strutting, 54

Receivers, 89
Relining Tunnels, 315
Boulder Tunnel, 315
Little Tom Tunnel, 321
Mullan Tunnel, 319
Repairing of Accidents in Tunnels, 308
Reservoirs, 86
Roof Arch Lining, 77
Roof Shield for Boston Subway, 251
Roof of Caissons, 287-291
Rotary Drills, 27
Ryder, B. H., 296

Saccardo System of Ventilation, 330
Saunders, W. L., 88
Seepage Water, 191
Seine River Tunnel, 293
Setting up Centers, 70
Severn Tunnel, 221
Shafts, Description of, 40
Shaler, Ira A., 142
Shield and Compressed Air Method, 263
Shield Construction:
Diaphragm, 256
Cellular Division, 255
Dimensions of Shields, 259
Front End, 254
General Form, 252
Rear End, 257
Shell, 253
Shield Method:
Barlow Shield, 242
Beach’s Shield, 245
Blackwall Tunnel Shield, 248
Brunel Shield, 240
City and South London Railway Shield, 250
Greathead’s Shield, 245
History, 238
Prelini’s Shield, 251
St. Clair River Tunnel Shield, 247
Side Shafts, 41
Side Tunnels Lining, 79
Side Walls Lining, 77
Simplon Tunnel, 103
Soils Encountered in Tunnels, 3
Sonnstein Tunnel, 99
Stations of Subways, 207-216
St. Clair River Tunnel Shield, 247
St. Gothard Tunnel, 132
Steam Power Plant, 85
Stratification of the Soils, 6
Strickler Tunnel, 96
Striking the Centers, 71
Strutting:
American Method, 174
Austrian Method, 177
Belgian Method, 146
Dimensions of Timber, 54
English Method, 167
Fort George Tunnel, 137
Full Section, 51
German Method, 156
Headings, 48
Italian Method, 183
Murray Hill Tunnel, 125
Pilot Method, 193
Quantity of Timber, 54
Shafts, 52
Iron: Full Section, 56
Headings, 56
Shafts, 57
Submarine Tunneling:
Cofferdam Method, 281
Compressed Air Method, 225
Detroit River Tunnel, 296
General Discussion, 218
Harlem River Tunnel, 285
Hudson River Tunnel Pennsylvania Railroad, 269
Lining, 261
Milwaukee Water-Works Tunnel, 226
Pneumatic Caisson Method, 284
Seine River Tunnel, 293
Severn Tunnel, 221
Shield and Compressed Air Method, 263
Shield System, 238
Sinking and Joining Sections Built on Land, 293
Van Buren Street Tunnel, 282
Subways:
Boston, 203
Cost of, 209-217
Cross-sections, 204-211
General Discussion, 195-202
Lining, 207-213
New York Rapid Transit Railway, 209
Stations, 207-216
Sutro, Adolph, 330

Tamping, 32
Thickness of Lining Masonry, 78, 83
Thomson Excavating Machine, 22
Timber Lining, 72
Timbering (see Strutting).
Tremies, 299
Trussed Centers, 70
Tunnel or Open Cut, 1
Tunnels:
Baltimore Belt Line, 160
Classification of, 42
Fort George, 135
Murray Hill, 123
Simplon, 103
St. Gothard, 132
Hard Rock, 84
Drift Method, 102
Comparison of Methods, 141
Heading and Bench Method, 152
Heading Method, 130
Soft Ground:
American Method, 172
Austrian Method, 176
Belgian Method, 144
English Method, 166
German Method, 155
Italian Method, 182
Pilot Method, 192
Quicksand Method, 188
Submarine:
Detroit River Tunnel, 296
Harlem River Tunnel, 285
Hudson River Tunnel of Pennsylvania Railroad, 269
Milwaukee Tunnel, 226
Seine River Tunnel, 293
Severn Tunnel, 221
Van Buren Street Tunnel, Chicago, 282
Under City Streets:
General Description, 201
Boston Subway, 203
Turbines, 86

Vacuum Method of Ventilation, 328
Value, Beverley R., 10
Van Buren Street Tunnel, 282
Ventilation, 325
Artificial, 327
Compressed Air, 330
Natural, 326
Plenum Method, 329
Quantity of Air, 331
Saccardo’s System, 330
Simplon Tunnel, 120
Vacuum Method, 328
Vernon-Harcourt, L. F., 221

Working Platforms, 286
Wyman, Erastus, 293

Transcriber’s Notes

Inconsistencies in spelling and hyphenation have been retained except
as mentioned below; non-English words and phrases have not been
corrected except as listed below. The (minor) differences between the
Table of Contents and the chapter headings have not been rectified.

Page 36/132: Figs. 14 and 61 are identical.

Page 92/93, Sommeilier: possibly an error for Sommeiller.

Page 134, Soummelier: possibly an error for Sommeiller.

Page 174, Footnote 11: presumably Fig. 92, indicating the planes of
the sections, is from the same publication.

Page 176, Austrian method: Dresden and Leipsic, and the Oberau Tunnel,
are (and were in 1837) in Saxony, Germany (or Prussia).

Page 179, The short transverse beam _c_, Fig. 90: there is no short
transverse beam visible in Fig. 90, nor is it clear which other figure
might be intended; there is therefore no hyperlink to the
illustration.

Page 279, Stirtling boiler: possibly an error for Stirling boiler.

Pages 337 and 342, Arlberg: possibly an error for Aarlberg.

Page 340, Wartha: possibly an error for Martha; Mertin: possibly an
error for Merten.

Changes made

Footnotes, tables and illustrations have been moved out of text
paragraphs; some table data have been re-arranged for better
legibility. In some of the formulas brackets have been added for
clarity.

Several obvious minor typographical and punctuation errors have been
corrected silently.

Page 12, footnote 3: Chapter IX. changed to Chapter X.

Page 35: on page 155 changed to on page 135

Page 36: on page 34 changed to on page 35

Page 53: The lagging plank may be ... changed to The lagging planks
may be ...

Page 113: (1) changed to (_I_) (2×)

Page 117: ... and it in this clearing ... changed to ... and it is in
this clearing ...

Page 130: as indicated by Fig. 58 changed to as indicated by Fig. 61

Page 136: as indicated in the Fig. 63 changed to as indicated in the
Fig. 65

Page 146: as shown by Fig. 63 changed to as shown by Fig. 69

Page 149: underpining changed to underpinning

Page 150: Since the roof arch rests for some time ... changed to Since
the roof arch rests are for some time ...; as shown by Fig. 66 changed
to as shown by Fig. 72

Page 172: illustrated in Fig. 12 changed to illustrated in Fig. 11

Page 175: page 127 changed to page 123

Page 179: as at _b_, Fig. 90 changed to as at _b_, Fig. 97

Page 204: The third type of section is shown by Fig. 116 changed to
The third type of section is shown by Fig. 117

Page 218: Malinö changed to Malmö

Page 261: Fig. 118 shows the hydraulic jacks changed to Fig. 136 shows
the hydraulic jacks

Page 282: shown by Fig. 119 changed to shown by Fig. 141

Page 297: towed down to the tunnel side changed to towed down to the
tunnel site

Page 315: shown in Figs. 141 and 142 changed to shown in Figs. 159 and
160

Page 324: shown by Fig. 148 changed to shown by Fig. 166

Page 338: given on page 50 changed to given on page 55

Page 340: Scloss Matrei changed to Schloss Matrei

Page 341: _Time._ changed to =Time.=

Page 348, entry Ryder: page number 296 added; Sounstein changed to
Sonnstein (2×).

Comments

Tunneling: A Practical Treatise.Chapter XXV

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