Copyright
Walter Loring Webb.

Railroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools online

. (page 1 of 15)
Online LibraryWalter Loring WebbRailroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools → online text (page 1 of 15)
Font size
QR-code for this ebook


This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project
to make the world's books discoverable online.

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject
to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books
are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover.

Marks, notations and other marginalia present in the original volume will appear in this file - a reminder of this book's long journey from the
publisher to a library and finally to you.

Usage guidelines

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing this resource, we have taken steps to
prevent abuse by commercial parties, including placing technical restrictions on automated querying.

We also ask that you:

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for
personal, non-commercial purposes.

+ Refrain from automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the
use of public domain materials for these purposes and may be able to help.

+ Maintain attribution The Google "watermark" you see on each file is essential for informing people about this project and helping them find
additional materials through Google Book Search. Please do not remove it.

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner
anywhere in the world. Copyright infringement liability can be quite severe.

About Google Book Search

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web

at http : //books . google . com/|



y Google



y Google



y Google



Digitized by VnOOQlC



Digitized by VnOOQ IC



Digitized by VnOOQ IC



y Google



WORKS OF
PROF. WALTER LORING WEBB

PUBLISHED BY

JOHN WILEY & SONS.



RjillitMd Construction. — Theory and Practice.

A Text-book for the Use of Students in Colleges
and Technical Schools. Fifth Edition. Revised
and Enlarged. 16mo. xvii + 789 pages and 217
figures and 10 plates. Morocco, $4.00 net.

Probiemt In the Use and Adluttment of Engineer^
Ing Instruments.

Forms for Field-notes; General Instructions for
Extended Students' Surveys. 16mo. Morocco,
$1.25.

The Bconooilcs of Railroad Construction.

Small 8vo. Second Edition, vii -|-347 pages, 35
figures. Cloth, $2.50.

The American Civil Engineers' Pocket Book

(AtUhor of Section on Railroads.)
Large 16mo. Morocco, $5.00.



Jfn



Digitized by VnOOQlC



RAILROAD CONSTRUCTION.



THEOBT AND PRACTICE.



A TEXT-BOOK FOB THE USE OF HTUDBNTS
m COLLEGES AND TECHNICAL SCHOOLS.



BY

WALTER LORING WEBB, C.E.,

Member American Society of Civil Engineers; Member American Railvay

Engineering AssocicUion; Aaeietan* Profeseor of Civil Engineer^

ing (Rnilrocd Engineering) in the Univergity of

Pen.isylvania, 1893-1901; etc.



^IFTH EDITION, REVISED AND ENLARGED.

TOTAL ISSnS TWCLVK THOUSAND.



NEW YORK

JOHN WILEY & SONS, Inc.

London: CHAPMAN & HALL, Limited

1914



y Google






<\A



,^^-



Copyright, 1899, 1903, 1908. 1913.

BY

WALTER LORING WEBB.



Digitized by VnOOQlC



'J



PREFACE TO FIRST EDmON.



The preparation of this book was begun several years ago,
when much of the subject-matter treated was not to be found in
print, or was scattered through many books and pamphlets, and
was h^ice imavailable for student use. Portions of the book
have already been printed by the mimeograph process or have
been used as lecture-notes, and hence have been subjected to
the refining process of class-room use.

The author would call special attenticm to the following
features:

a. Transition curves; the multiform-compound-curve method
is used, which has been followed by many rsdlroads in this
coimtry; the particular ciur^es here developed have the great
advantage of being exceedingly simple, and although the method
is not theoretically exact, it is demonstrable that Hie differences
are so small that they may safely be neglected.

b. A system of earthwork computations which makes the multi-
plication and redaction in a single operation by means of a slide-
rule and which enables one to compute readily the volume of the
most complicated earthwork forms with an accuracy which is only
limited by the precision of the cross-sectioning.

c. The "mass curve" in earthwork; the theory and use of
this very valuable process.

d. Tables I, II, III, and IV have been computed ab novo.
Tables I and II were checked (after computation) with other
tables, which are generally considered as standard, and all
discrepancies were further examined. They are believed to be
perfect.

e. Tables V, VI, VII, and IX have been borrowed, by per-
mission, from ''Ludlow's Mathematical Tables." It is believed
that five-place tables give as accurate results as actual field

0|-|^ p^A O °'^' ''""^ ^^ Google



IV PREFACE TD SECOND EDITION.

practice requires. Tables VIII and X have been compiled to
conform with Ludlow's system.

The author wishes to acknowledge his indebtedness to Mr.
Chas. A. Sims, civil engineer and railroad contractor, for reading
and revising the portions relating to the cost of earthwork.

Since the book is written primarily for students of railroad
engineering in technical institutions, the author has assumed
the usual previous preparation in algebra, geometry, and trigo-
nometry.

Walter Lorinq Webb.

TjNrVERSITY OF PENNSYLVANIA,
PHIULDELPHIA,

Jan. 1,1900.



PREFACE TO SECOKD EDITION.



Since the issue of the first edition the author has conferred
with many noted educators in civil engineering, among them the
late Professors E. A. Fuertes and J. B. Johnson, regarding the
most desirable size of page for this book. The inconvenience of
the octavo edition for field-work was found to be limiting its use.
It was therefore decided to recast the whole work and reduce
the pa^ge from "octavo" to "pocket-book" size. Advantage
was then taken of the opportunity to revise freely and to add
new matter. The original text has now been almost doubled by
the addition of several chapters on structures, train resistance,
rolling stock, etc., and also several chapters giving the funda-
mental principles of the economics of railroad location. Those
who are familiar with the late Mr. Wellington's masterpiece,
"The Economic Theory of Railway Location," will readily ap-
preciate the author's indebtedness to that work. But 'v^ile the
same general method has been followed, the author has taken
advantage of the classification of operating expenses adopted
by the Interstate Conmierce Commission, has used the figures



y Google



PREFACE TO THIRD AND FOURTH EDITION. V

pubUi^ed by them (which were unavailable whesn Mf. Welling-
ton wrote), and has developed the theory on an independent
basis, with the exception of a few minor details. Those who
deny the utility of such methods of computation are referred to
§§367, 426, and elsewhere for a practical discussion of that
subject. '

The authot^s primary aim has been to produce a "text-book
for students," and the subject-matter has therefore been cut
down to that which may properly be required of students in
the time uaially allotted to railroad work in a civil-engineering
curriculum. On this account no extended discussion has been
given to the multitudinous forms of various railroad devices
in the chapters on structures. The aim has been to teach the
principles and to guide the students into proper methods of
investigation.

January, 1903.



PREFACE TO THIRD EDITION.



In the present edition Tables IX and X have been entirely
changed, the tables having been rewritten so that the values
are given for single minutes rather than for each ten minutes.
There has also been added a table of squares, cubes, square
roots, cube roots, and reciprocals, which are frequently of so
great service in computations. Advantage has also been taken
of the opportunity to make numerous typographical and verbal
changes.

February, 1905.



PREFACE. TO FOURtH EDITION.



In this edition a very extensive revision has been made in
the chapter on Earthwork. Table XXXIII, giving the volume
of level sections, has been added to the book, with a speciaj
demonstration of the method of utilizing this table for pre*

Digitized by VnOOQlC



VI PBEFACB TO FIFTH EDITION.

liminary and approximate earthwork calculatloiis. A danon-
stration, with table, for determining the economics of ties has
also been added. In accordance with the suggestions of Prof.
R. B. H. Begg, of Syracuse University, additions have been
made to Table IV, which facilitate the solution of problems in
transition curves. Very numerous and sometimes extensive
alterations and additions, as well as mere verbal and typo-
graphical changes, have been made in various parts of the
book. The chapters on Economics have been revised to make
them conform to more recent estimates of cost of operation.
July. 1008.



PREFACE TO FIFTH EDITION.



The very radical changes made, during recent years, by the
Interstate Commerce Conmiission, in the analysis of operating
expenses of railroads, have required that all of the chapters on
Economics should be almost entirely rewritten. The writer has
also ^ideavored to make all recommendations as to construction
work to conform with the most recent reconmiendations on those
points by the American Bailway Engineering Association, who
granted the Author special permission to m£tke such quotations.
This gives all such statements the highest possible authority.
Advantage wrj3 taken of the opportunity to correct minor typo^
graphical errors and blemishes which have been discovered since
issuing the fourth edition.

March. 1913.



Digitized by VnOOQlC



TABLE OF CONTENTS.



CHAPTER I.

RAIIAOAD aXTRYETB,

PAOB
Reconnoibsancb 1

1. Character of a reconnoissance survey. 2. Selection of a gen-
eral route. 3. Valley route. 4. Cross-country route. 5. Moun-
tain route. 6. Existing maps. 7. Determination of relative
elevations. Barometrical method. 8. Horizontal measurementSt
bearings, etc. 9. Importance of a good reconnoissance.

PREUMINARY BTJRVBYS

10. Character of a survey. 11. Cross-section method. 12.
Croea-sectioning. 13. S.tadia method. 14. "First" and "sec-
ond" preliminary survey.
Location burvets 18

15. "Paper location." 16. Surveying methods. 17. Form
of Notes.

CHAPTER II.

ALiQNMENT.
SlMPL£ CURVES 19

18. Designation of curves. 19. Length of a subchord. 20.
Length of a curve. 21. Elements of a curv^e. 22. Relation be-
tween r, E^ and J. 23. Elements of a 1° curve. 24. Exercises,
25. Curve location by deflections. 26. Instrumental work. 27.
Curve location by two transits. 28. Curve location by tangential
offsets. 29. Curve location by middle ordinates. 30. Curve
location by offsets from the long chord. 31. Use and value of the
above methods. 32. Obstacles to location. 33. Modifications of
locatioxi. 34. Limitations in location. 35. Determination of the
curvature of existing track. 36. Problems.

COMPOHKD CURVES 38

37. Nature and use. 38. Mutual relations of the parts of a com-
pound curve having two branches. 39. Modifications of location.
40. Froblemsb

vii



Digitized by



Google



VIU TABLE OF CONTENTS.



PAGE

Transition curves 43

41. Superelevation of the outer rail on curves. 42. Practical
rules for superelevation. 43. Transition from level to inclined
track. 44. Fundamental principle of transition curves. 45.
Multiform compound curves. 46. Required length of spiral. 47.
To find the ordinates of a l*-per-25-feet spiral. 48. To find the
deflections from any point of the spiral. 49. Ck>nnection of spiral
with circular curve and with tangent. 50. Field-work. 51. To
replace a simple curve by a curve with spirals. 52. Application
of transition curves to compound curves. 53. To replace a com-
pound curve by a curve with spirals. 63a. Use of Table IV.

Vertical curves 61

54. Necessity for their use. 55. Required length. 56. Form
of curve. 57. Numerical example.

CHAPTER III.
earthwork.

Form of excavations and embankments 65

58. Usual form of cross-section in cut and fill. 59. Terminal
pjnramids and wedges. 60. Slopes. 61. Compound sections.
62. Width of roadbed. 63. Form of subgrade. 64. Ditches.
65. Effect of sodding the slopes, etc.

Earthwork surveys 73

66. Relation of actual volume to the nimierical result. 67.
Prismoids. 68. Cross-sectioning 69. Position of slope-stakes.
70» Setting slope-stakes by means of "automatic" slope-stake
rods.

Computation op volume 7ft

71. Prismoidal formula. 72. Averaging end areas. 73. Middle
areas. 74. Two-level ground. 76. Level sections. 76. Numeri-
cal example, level sections. 77. Equivalent sections. 78. Equiv-
alent level sections. 79. Three-level sections. 80. Computation
of products. 81. Five-level sections. 82. Irregular sections.
83. Volume of an irregular prismoid. 84. Numerical example;
irregular sections; volume, with approximate prismoidal correc-
tion. 85. Magnitude of the probable error of this method. £0
Numerical illustration of the accuracy of the approximate rule.
87. Cross-sectioning irregular sections. 88. Side-hill work, 89.
Borrow-pits. 90. Correction for curvature. 91. Eccentricity of
the center of gravity. 92. Center of gravity of side-hill sections.
93. Example of curvature correction. 94. Accuracy of earthwork
computations. 95. Approximate computations from profiles.

Formation op embankments 114

96. Shrinkage of earthwork. 97. Proper allowance for shrink-
age. 98. Methods of forming embankments.

Computation op haul 120

99. Nature of subject. 100. Mass diagram. 101. Properties



y Google



TABLE OF CONTENTS. tX



PAOB

of the mass curre. 102. Area of the mass curve. 103. Value of
the mass diagram. 104. Changing the grade line. 105. Limit of
free haul.

Elements of the cost of eabthworr 128

106. Analysis of the total cost into items. 107. Loosening.
108. Loading. 109. Hauling. 110. Choice of method of haul
dependent on distance. 111. Spreading. 112. Keeping roadways
in order. 112a. Trimming cuts to their proper cross-section.

113. Repairs, wear depreciation, and interest on cost of plant.

114. Superintendence and incidentals. 115. Contractor's profit
and contingencies. 116. Limit of profitable hauL

BiASTiNo • • 149

117. Explosives. 118. Drilling. 119. Position and direction
of drill-holes. 120. Amount of explosive. 121. Tamping. 122.
Exploding the charge. 123. Cost. 124. Classification of ex*
cav&ted material. 125. Specifications for earthwork.

CHAPTER IV.
tbestles.

126. Extent of use. 127. Trestles va. embankments. 128. Two

principal types I59

Pii«B trestles X61

129. Pile bents. 130. Methods of driving piles. 131. Pile-
driving formulse. 132. Pile-points and pile-shoes. 133. Details
of design. 134. Cost of pile trestles.
Framed trestles 167

135. Typical design. 136. Joints. 137. Multiple-story con-
struction. 138. Span. 139. Foundations. 140. Longitudinal
bracing. 141. Lateral bracing. 142. Abutments.
Floor systems 173

143. Stringers. 144. Corbels. 145. Guard-rails. 146 Ties on
trestles. 147. Superelevation of the outer rail on ciirves. 148.
Protection from fire. 149. Timber. 150. Cost of framed timber
trestles.
Design of wooden trestles 179

151. Common practice. 152. Required elements of strength.
153. Strength of timber. 154. Loading. 155. Factors of safety.
156. Design of stringers. 157. Design of posts. 158. Design
of caps and sills. 159. Bracing.

CHAPTER V. I

TUNNELS.

BUAVJOVINO •... 189

160. Surface surveys. 161. Surveying down a shaft. 162.
Underground surveys. 163. Accuracy of tunnel surveying.

Design I94

164. Cross-sections. 165. Grade. 166. Lining. 167. Shafts.
168. Drains.

Digitized by VnOOQlC



X TABLE OP CONTENTS.

PAGS

CoNSTRtronoN ,, 199

169. Headings. 170. Enlargement. 171. Distinctive features
of various methods of construction. 172. Ventilation during oon-
stniction. 173. Excavation for the portals. 174. Tunnels v«.
open cuts. 175. Cost of tunneling.

CHAPTER VI.

CULVERTS AND MINOR BRIDQES.

176. Definition and object. 177. Elements of the dedgn 207

Area op the waterway 208

178. Elements involved. 179. Methods of computation of area.
180. Empirical formuUe. 181. Value of empirical formula. 182.
Results based on observation. 183. Degree of accuracy required.

Pipe culverts 212

184. Advantages. 185. Construction. 186. Iron-pipe culverts.
187. Tile-pipe culverts.

Box CULVERTS 216

188. Wooden box culverts. 189. Stone box culverts. 190. Old
rail culverts. 190a. Reinforced concrete culverts.

Arch culverts 221

191. Influence of design on flow. 192. Example of arch-cul-
vert design.

Minor openings 222

193. Cattle-guards. 194. Cattle-passes. 195. Standard stringer
and I-beam bridges.

CHAPTER VII.

BALLAST.

196. Purpose and requirements. 197. Materials. 198. Cross-
sections. 199. Methods of laying ballast. 200. Cost 227

CHAPTER VIII.

TIES AND OTHER FORMS OF RAIL SUPPORT.

201. Various methods of supporting rails. 202. Economic? of

ties 237

Wooden ties ' 238

203. Choice of wood. 204. Durability. 205. Dimensions.
206. Spacing. 207. Specifications. 208. Regulations for laying
and renewing ties. 209. Cost of ties.

Preservative processes for wooden ties 242

210. General principle. 211. Vulcanizing. 212. Creosoting.
213. Bumettizing. 214. Kyanizing. 215. Wellhouse (or zinc-
tannin) process. 216. Cost of treating. 217. Economics of
treated ties.



Digitized by



Google



TABLB or CONTENTS. JO

PAOB

MetaIj ties 260

218. Extent of use: 210. Durability. 220. Fonn and dimea-
siona of metal crofls-ties. 221. Fastenincs. 222. Ck>st. 223.
Bowls or plates. 224. Longitudinals. 224a. Reinforced eonorete
ties.

CHAPTER IX.

JtMUi.

225. Early forms. 226. Present standard forms. 227. Weight
for various kinds of traffic. 228. Effect of stiffness on traction.
229. Length of rails. 230. Expansion of rails. 231. Rules for '
allowing for temperatiu-e. 232. Chemical composition. 233.
Proposed standard specifications for steel rails. 234. Rail wear
on tangents. 235. Rail wear on curves. 236. Ck)st of rails 256



CHAPTER X.

BAIIr-FASTENINGS.
RAIIi-JOINTB 270

237. Theoretical requirements for a perfect joint. 238. Effi-
ciency of the ordinary angle-bar. 239. Effect of rail-gap at joints.
240. Supported, suspended, and bridge joints. 241. Failures of
rail-joints. 242. Standard angle-bars. 243. Later designs of rail-
joints. 243a. Proposed specifications for steel splice-bars.

Tie-plates 276

244. Advantages. 245. Elements of the design. 246. Methods,
of setting.

Spikes 280

247. Requirements. 248. Driving. 249. Screws and bolts.
250. Wooden ^ikes.

TRACK-BOi;r8 AND NUT-LOCKS 284

251. Essential requirements. 252. Design of track-bolts. 263.
Design of nut-locks.

CHAPTER XI.

SWTTCBES AND CROSSINGS.

Switch coNSTRncrioN 289

254. Essential elements of a switch. 255. Frogs. 256. To find
the frog number. 257. Stub switches. 258. Point switches. 259.
Switch-stands. 260. Tie-rods. 261. Guard-rails.

IfATHEMATICAL DEBIQl^ OI* SWTfCHEft 297

262. Design with circular lead rails. 263. Effect of straight frog-
rails. 264. Effect of straight point-rails. 266. Combined effect
of straight frog-rails and straight point-rails. 266. Comparison of
the above methods. 267. Dimensions for a turnout from the
OUTER side of a curved track. 268. Dimensions for a turnout from
the INNER side of a curved track. 269. Double turnout from a



Digitized by



Google



XU TABLE OF CONTENTS

PAQB

straight track. 270. Two turnouts on the same sUe. 271. Con-
necting curve from a straight track. 272. Connecting curve from
a curved track to th6 outside. 273. Connecting; curve from a
curved track to the inside. 274. Crossover between two parallel
straight tracks. 275. Crossover between two parallel curved
tracks. 276. Practical rules for switch-laying.

Cbobsingb 319

277. Two straight tracks. 278. One straight and one curved
track. 279. Two curved tracks. 279a. Slipg.

CHAPTER XII.

IflSCBLIiANEOUS BTRUCTUBBS AND BUILDINGS.
WaTEB stations AND WATER SUPPLY 826

280. Location. 281. Required qualities of water. 282. Tanks.
283. Pumping. 284. Track tanks. 285. Stand pipes.

Buildings 831

286. Station platforms. 287. Minor stations. 288. Section
houses. 289. Engine houses.

Snow structures 336

290. Snow fences. 291. Snow sheds.
Turntables ..• "'^'j

CHAPTER XIII.
tardb and terminals.

293. Value of proper design. 294. Divisions of the subject. ... 340

Freight yards ^^'

295. General principles. 296. Relation of yard to main tracks.
297. Minor freight yards. 298. Transfer cranes. 299. Track
scales.
Enoinb yards 3 'S

300. General principles.

Paabbngbb terminals 85*

CHAPTER XIV.
block signaling.

GbNBRAX« PBINCIPLE8 351

301. Two fundamental systems. 302. Manual systems. 303.
Development of the manual system. 304. Permissive blocking.
305. Automatic systems. 306. Distant signals. 307. Advance
signals.

Mbchanical dbtails. . t 35V

308. Signals. 309. Wires and pipes. 310. Track circuit for
automatic signaling.



Digitized by



Google



TABLE OP CONTENTS. XIU

CHAPTER XV.

ROLIiINO STOCK.

PAOB

Wheels and rails 363

311. Effect of rigidly attaching wheels to their axles. 312.
Effect of parallel axles. 313. Effect of coning wheels. 314.
Effect of flanging locomotive driving wheels. 315. Action of a
locomotive pilot- truck.

LOCOlfOTIVEB.

General structure 870

316. Frame. 317. Boiler. 318. Fire box. 319. Coal con-
sumption. 320. Heating surface. 321. Loss of efficiency of
steam pressure. 322. Tractive power.

Running gear 8S|

323. Tyj 3S of running gear. 324. Equalizing levers. 325.
Counterbat.ncing. 326. Mutual relations of the boiler power,
tractive power and cylinder power for various 'types. 327. Life
of locomotives.

CARS.

328. Capacity and size of cars. 320. Stresses to which car-
frames are subjected. 330. The use of metal. 331. Draft gear.
332. Gauge of wheels and form of wheel tread S03

TRAIN-BRAKES. ,

333. Introduction. 334. Laws of friction as applied to this

problem 399

VIechanism or brakes 403

335. Hand-brakes. 336. "Straight" air brakes. 337. Auto-
matio air brakes. 338. Tests to measure the efficiency of brakes.
339. Brake shoes.

CHAPTER XVI.

train resistance.

340. Classification of the various forms. 341. Resistances inters
nal to the locomotive. 342. Velocity resistances. 343. Wheel
resistances. 344. Grade resistance. 345. Curve resistance. 346.
Brake resistances. 347. Inertia resistaooe. 348. Dynamometer
tests. 349. Gravity or "drop" tests. 350. Formulae for train
resistance 409

CHAPTER XVII.
cost of railroads.

351. General considerations. 352. Preliminary financiering.
353. Surveys and engineering expenses. 354. Land and land



y Google



XIY TABLE OF CONTENTS



PAOB

damages. 355. Clearing and grubbing. 356. Earthwork. 357.
Bridges, trestles and culverts. 358. Trackwork. 359. Buildings
and miscellaneous structures. 360. Interest on construction.
361. Telegraph lines. 362. Detailed estimate of the cost of a line
of road. . .' , ... 42?



PART II.

RAILROAD ECONOMICS.

CHAPTER XVIII.

INTBODUCTIpN.

363. The magnitude of railroad business. 364. Cost of trans-
portation. 365. Study of railroad economics — its nature and


1 3 4 5 6 7 8 9 10 11 12 13 14 15

Online LibraryWalter Loring WebbRailroad construction. Theory and practice. A textbook for the use of students in colleges and technical schools → online text (page 1 of 15)