CHAPTER XXV.

Chapter 254,563 wordsPublic domain

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×).