File:Electric railway journal (1913) (14574901890).jpg

Identifier: electricrailway421913newy (find matches)
Title: Electric railway journal
Year: 1908 (1900s)
Authors:
Subjects: Electric railroads
Publisher: (New York) McGraw Hill Pub. Co
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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r efforts to elimi-nate this common but inexplicable phenomenon. ballast is 6 in. Some engineers, however, have made thedepth as shallow as 5 in., and others have increased itto 9 in. The question of draining this type of track con-struction does not appear to have received serious con-sideration, as comparatively few companies have pro-vided tile drains either under the center of each track orin the space between the ends of the ties in double track. In connection with the use of crushed rock or gravelfor ballast under track in paved streets, the types em-ployed by the Milwaukee Electric Railway & Light Com-pany and the Twin City Rapid Transit Company, whichare somewhat similar, have been found to produce aspermanent a track as may be desired. Coarse crushedrock or gravel is employed in both designs and is placedin the trench to a depth of 6 in. and thoroughly rolled inplace by a road roller, Over the top of this sub-ballastlayer the Milwaukee Electric Railway & Light Company
Text Appearing After Image:
Girder Grooved Rail on Combination Ballast and Concrete Foundation, United Railroads of San Francisco With this type of construction the most permanent re-sults are obtained by the use of a crushed stone of firstquality and of a size to pass through a 2/2-in. ring. Thisstone is screened to remove the fine particles which, afterthe ballast is in place, tend to filter out with moisture,causing a shifting roadbed. Construction of this character compares vary favorablywith that where a concrete foundation is used if theinstallation has been thoroughly guarded. Where sub-soil conditions give evidence of instability, however, bal-lasted track construction should not be employed. It isobjectionable in instances of this character becausecrushed stone does not act as a unit in a way similarto a solid concrete slab, but the load on each tie is car-ried to the subgrade independently. Hence, if there isthe slightest giving way in the subsoil, the track begins topump, and this finally results in i

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