The Birmingham age-herald., 1920-05-05

heaviest traffic road in the vicinity, both in number and tonnage of ve- hicles. There are at present a number of large and important industries along this road, and 1t is certain that the largest future industrial development Of this district will be in territory ad- jacent to this road. It Is, therefore. a certainty that this road will carry
 a constantly increasing traffic for many years to come. In view of these facts we unanimously agree that this $ one road, in particular which shoul
 be costructed in most thorough and permanent manner. We also think that
 there should not be used upon this road any type of construction regard ing which there is the slightest doubt
 as to suitability to traffic conditions
 or relative permanence.
 We have studied the previous rec ommendation of the engineers, that this road be built upon a reconstructed chert and slag foundation, rather than upon concrete foundation, and after full discussion and personal examina- tion of the present chert road, we are ! forced to the conclusion that this form of construction would be most unwise and that a large portion of the peo- ples investment in good roads, and the people of Jefferson county look upon this bond money as an invest ment, would be seriously ieopardized. Our reasons for this conclusion are
 set forth below.
 1. The character and volume of traf- fife to be carried by a road should be 1 two of the most important factors con sidered in deciding upon the type of construction. Although in advertising the bond issue 1t was stated that the plans for construction would be large ly based upon traffic census, we are unfortunate in not having a recent, authentic and accurate census of the North Bessemer road. The observation of members of this committee and others indicate that this road carries
 an enormous volume of traffic. much of which is of the most severe type, such as the hauling of heavy ma chinery and castings between the Ems 1 ley and Fairfield plants of the Ten nessee Company.
 It is a matter of common rumor that in the not distant future the Tennessee
 Coal, Iron and Railroad Company, as well as other corporations owning prop erty and plants in Opossum valley, will make large additions to their present great plants. Construction of such mag nitude will bring an enormous and ab- normal development of traffic because or the great tonnage of building materials which will have to be moved over this road As these plants are completed,
 one by one, the normal traffic of the road will be constantly increasing.
 The modern high speed motor truck in u oduces a problem which requires the utmost ingenuity of the engineer and the most substantial construction to meet. The problem is particularly marked on a country road. and is more severe than on city street, because of the high CT average speed maintained on coun- try road. A slightly higher speed of five or ten-ton truck means trertendous increase in the abrasion and impact to which the road is subjected. 9A recon structed basex of the type proposed for tkis project will not withstand these con ditions of this road which will not be overcome by construction, as will be ex- plained below.
 9 The present road is In some DOT tions poorly located and to conform to proper standards of highway engineering practice, will have to be relocated over considerable portion of it's length. Your enginer informs us that approximately ore-third of the road will be relocated It is self evident that the new portions of the road cannot be classed as recon structed, but must be considered as pure ly new construction on new grade. It IS evident that such a grade is not thor oughly settled, and we believe that the tt rifle wear and tear of modern traffic would soon seriously dispace the Sag base on such a grade, with consequent failure of the wearing surface.
 B. Although the plans call for the new road to be IS feet wide, the average width of sound road metal on present road IS about 16 feet with a minimum of IA feet These widths were determined carefully and accurately by our personal measure ments It is evident that to widen the road either one foot of new fill will have to be added on each side of the road or two feet on one side. This new fill will not be nearly so solid as the old road bed alongside it, and there will be the everpresent possibility of it going down under heavy traffic We believe that properly constructed concrete foundation is more likely to resist thls condition than one, two or three inches of alag laid on the chert as in the proposed re- constructed base.
 4. The crown of the present road is probably one-haf inch or more to the foot of width, whereas the crown of the proposed road will certainly not be more than one-quarter inch to the foot. To bring the cross section of the road to proper shape it will be necessary either to cut down the center of the road orr to
 
 down there is grave danger of cutting clear through the chert surface, and then laying say two inches of slag on the original earth or clay grade. Rolling will find some of the soft places. but heavy motor trucks will find some that the roller will miss
 3. The best practice of the day re- qlires that curbs or headers be built along each side of a bituminous road, particularly when a macadam base is used Without such curbs raveling along the edges of the road is likely to occur. Broken edges soon creep into the center of the road. as may readily be observed on the present Third avenue road to Ensley None of us wish to reproduce tkis road on the North Bessemer project.
 Curbs of the type required would doubt less cost approximately $7,5O0 per mile. If they were used with reconstructed base as they should be. approximately $GO. coo should be added to the recom- mended bid for Warrenite on reconstruct ed base
 6, So far as we can learn there are several estimates as to the thickness of the chert at present on the road, but there evidently has been no detailed sur Vey. made by digging test holes at fre- quent and regular intervals. Usually such survey shows the thickness of the road metal much less than the es- innate. The proposal called for 240 cubic yards of Aag for reconstructed base course. but this is admitted to De merely guess as to quantity This amount of slag would, however, permit of layer of slag only one inch thick being laid over the chert on the entire yardage of s53O2 square yards including the entirely new grade. It is manifest