Arizona republican., 1919-02-25
TELLS CLUB OF VALUE IF BUILDING MODERN
 CONCRETE HIGHWAYS

Modern Concrete Paved Highways was the subject of an interesting ad- dress by William C. Hartranit before the Brotherhood club at their luncheon yesterday. With the bill before the state legislature proposing the eNpendl- turc of very large amount of money in the construction of highways in Ari- zona, the talk was especially interest ing.
 MT. Hartranft said in part:
 Concrete pavements for highways have long since passed the eXperi- mental stage. Improvements in meth Ods of construction and details of de- sign continue Co be developed, as will be true of any type of structure. but the fundamental principles have now been so thoroughly understood for Q number of years that a definite prac- ticc has been developed which can he counted upon Go render true values for he investment.
 The first section Of the country to build concrete highways on a large scs9e was Wayne county. Michigan. of which Detroit is the seat Beginning i'm the year 1908 the authorities os this county have followed a plan of high way development which was origin ally conceived in 1907 and year by year they have added to the paved sections or this system until now it is nearly complete.
 It will be seen by the last annual report of the board of county road commissions of Wayne county. Mich. that they have found no reason to de- part from the cement concrete type of road.
 Profiting by tho experience Of Wayne county and other sections where con crete highways have been in use for many years. road builders now advo- cate a paved width of not less than IS Feet for main line highways carrying heavy traffic and a width of 20 feet wherever tt is at all possible to make the necessary additional investment The ordinary motor car is slightly more than six feet n width and the average motor truck is apt to be some what wider than that. thus it is seen thaJ pavement havingsa width of but lo feet does not give very comfort able margin at clearance when ve- hlcleS pass each other at speeds above To or 20 miles an hour.
 The present eastern standard prac- tce develops the fact that concrete pavement mixed in the proportions ol one volume ot cement, two volumes ol sand and three volumes of stone shoulc nave @ thickness of six inches at the edge or the pavement and eight inches m the center. This gives a curved sur lace or crown which sheds the water perfectly and still is SO mperceptibl, that no discomfort is occasioned Co oc. tupants of vehicles driving on the roaf at tho higher speeds.
 california has many miles Of cement concrete roads made of one volume ot cement. two volumes Of sand. and fou volumes Of stone only four inches thick mat IS proving satisfactory in mosi places, although it is considered b, many engineers as too light construc. ton for motor truck traffic.
 The question is often raised as f, whether the necessary investment tf pave with concrete is a good one ol not. An answer Co this is found ir some pcent tests which were con. ducted by the Portland Cement asso. eiation with the cooperation of th, White Motor Car company on the high. ways near Cleveland. ohio. Severa Secuons ot highway were selected some Of which were natural eartf roads in good condition. others wcr, surfaced with gravel biuminous and concrete pavements. A string off fiv, --toh trucks we're used tn this ,scrie. "t tests and the results in gasoline con. sumption were averaged for repeato. runs by all five vehicles over all O these different sections of highway The economy in operation of truck. over the different pavcrut nts is d.s closed by tho average mileage obtained rom gallon ot gasoline. It was foun, lnat on the ordinary dirt road in 300, condition. the average Of oll the test, was '.'S miles per gallon. while ol th, concrete roads ll.7S miles were ob lained from gallon of fuel. Tn, mileage over the brick pavemerts ii good condition was almost the same a. was obtained on the concrete. a.thorg, the mileage in the case Of the aricj Vas slightly lower per -sifcr rhan fc