110 - ANNUAL REPORT 
tie rods spaced at frequent intervals. The shape of the concrete which 
forms the rail bed is varied by different engineers, but the same result is 
obtained. The track and paving become one solid whole. The following 
estimate of the cost of one mile of such track, using a grooved rail, is 
given by Mr. B. J. Arnold, M. Am. Inst. Elec. E. Many of the prices used 
in the estimate will vary, of course, according to the market and local 
conditions ; this estimate was made for Chicago, early in 1903. 
Estimated Cost of One Mile of Grooved Rail Track with Concrete 
Beam Support. 
Excavation and hauling, 2,000 cu. yds. at $1.00 ........ $ 2,000 00 
Concrete beams S00 CuUssydSwati oO: 00m re:qce iene carers aeerecne 4,800 00 
Steel rails, 120 lbs. per yard, 188.57 tons at $41.00....... 7,731 00 
Hawline trails torstreets atcoleO Ole tenctls chee crater tenants 189 00 
Ties TOGS TOO At ASOD Dera levee tacts arate a Pattee eee epee rare 175. 00 
Castiweldediwjoimts ol7iGh ati b: OOM aaskenys caren catiteeatere 880 00 
CPOSS MOT ees bs ehh uy Paya For Ne Sarre ais Pee Meee Une m 10 00 
Trackwlayine. cleanine7streel wretch va. ae acuenisee cient 1,501 00 
Special track work per mile of single track .............. 4,500 00 
Engineering, supervision and administration at 10% .... 2,179 00 
Total cost of track exclusive of paving............ $23,965 00 
ROAD FOUNDATIONS 
For years concrete foundations for paved streets have met the decided 
approval of municipal engineers. The engineer who fails to consider 
the foundation to be one of the most important essentials of a well paved 
street fails to secure economy and durability in the streets he paves. 
Better an inferior wearing surface upon a first class, solid, impervious 
foundation, than a high grade wearing surface upon a yielding pervious 
foundation. In the first case only the wearing surface needs renewing 
after a short period, while in the latter case the whole construction in- 
cluding the road-bed must be overhauled in order to secure a decent street. 
Of all the foundation materials employed, none so nearly meet all. the 
requirements as does well laid concrete. It is rigid, distributing the load 
of traffic to a large bearing surface of soil; being rigid, it does not allow 
deformation of the wearing surface and the consequent abrasion due to 
such deformation; it prevents water reaching the soil of the road-bed, 
and thus the subgrade gives firm support to the foundation. It is easily 
and perfectly repaired when it becomes necessary to cut into a street for 
subsurface connections of any kind. It is durable to the maximum limit 
of man’s observation. It is not much more expensive than a well rolled 
broken stone or gravel foundation, which is next in importance for such 
purposes. 
The thickness required varies from 4 to 8 inches according to the 
traffic and to the character of the subsoil. Six inches is the usual depth 
