DUST PEEVENTION AND EOAD PBESERVATION, 1914. 



21 



Experiment No. 6. (Water-Gas Tar Preparation — Hot Application). 



This experiment bled rather freely in the spring and required con- 

 siderable top-dressing and repairs, especially on the trap section. 

 The surface does not become muddy, although dampness shows 

 through along several areas where subdrainage is poor. Most of the 

 repairs so far have been due to some little stripping of the bitumen 

 that occurred early in the spring before top-dressing could be applied. 

 Such repairs have, however, been few, and less bitumen has been 

 required than on any of the other experiments. 



Experiment No. 7 (Asphaltic Petroleum — Cold Application). 



The surface of this experiment worked into a rather objectionable 

 muddy condition as soon as the winter of 1913-14 brought continued 

 wet weather and frost. In the spring it ironed out and presented 

 a very satisfactory appearance until about September. At this time 

 numerous small weaknesses began to develop which, owing- to cold 

 weather, could not all be repaired before winter. Nevertheless, the 

 surface has not become so muddy this winter (1914-15) as last, but 

 the mud which is formed is in some spots a lighter brown color, indi- 

 cating that the oil is losing its effect. This experiment is expected to 

 require re-treatment at the earliest possible time in the spring, and 

 may require considerable patching, as indicated by the rapidly increas- 

 ing breaks in the surface during the late fall of 1914. 



Table 13. — Materials and cost data for renewal treatments of experiments Nos. 2 and 3 

 Rockville Pike, Maryland, 1914- 



Experiment No. 2. 



Trap. 



Experi- 

 ment 

 No. 3. 



Torpedo 

 sand. 



Length feet . 



Area square yards.. 



Bituminous material, pt-r square yard gallons. 



Covering m kterial, per square yard cubic yards. . 



liare yard;: 



l 



Bituminous material 



Applying bituminous materia] 



ring material ■ 



■ling co wring material 



4,330 

 7,210.6 

 .294 

 .012 



3,050 

 083.4 

 .294 

 .012 



7,400 

 12,333 



.170 



. 009 



2.79 

 (') 

 1.39 

 .53 



2.79 



(1) ™ 

 2. 52 



.53 



0. 048 

 1.234 



. 393 



1. 994 



.197 



Total coat. 



7.71 



...si 



3. 866 



' Automobile distributor cued; sweeping and applying Included In cost ol material. 



A traffic census on the Rockville Pike is taken every 13 days for a 

 24-hour period. A tabulation of the maximum and average of each 

 class of traffic for the period between January 1, L914, and January 1, 

 191 5, is given in Table I l. 



