DUST PREVENTION AND ROAD PRESERVATION, 1916. 51 
Experiment No. 4—Residual asphaltic petroleum, hot application.— 
Although section 4 had been patched heavily for over a year, it was 
decided in the summer to attempt to carry it through one more win- 
ter without general re-treatment. It was somewhat doubtful whether 
this was the best policy, for the section was acting very much as 
section 7 did during its second winter when re-treatment was post- 
poned. There were a great number of breaks, small but prevailing 
generally over most of the section, showing more or less uniform fail- 
ure of the mat. At some points a slight rutting had begun and made 
probable the necessity for very heavy patching and re-treatment 
early in the season. 
Experiment No. 5—Residual asphaltic petroleum, hot application.— 
The condition of this experiment was comparable with that of expe- 
riment No. 4, although the disintegration did not appear to be quite 
so uniform. Though the surface was wet in all bottoms and poorly 
drained sections, there were larger areas almost intact. On the wet 
sections, the mat showed a tendency to break and form mud and 
considerable patching and it was thought a general re-treatment would 
be necessary the following summer. 
TABLE 53.— Materials and cost data for surface re-treatment, Rockville Pike, in 1916. 
Experi- Experi- Experi- 
Experi- | ment No. 2,| ment No.3,| ment No.7, 
Item. ment No. 1 refined asphaltic | asphaltic 
zm efined coal water-gas | petroleum | petroleum 
tar (cold). (cold). (cold). 
AUD GREG Shes eecsecesese sscecsese=0 square yards. . 4, 825 7,475 12,333 11, 148 
Quantity of material per square yard: 
Bituminous materials .: 2 0. 4{2eees- see ces gallons. - 0.383-+ 0.157 0. 154 0.16 
(Gig Als = tee oe ae ee een One cubic yards. - - 011+ PC (Si See mae el [sy gs oe 
MHA ee see eae ioite esate ais mnie nynis asain ale ayolo Sialsintale Gp e6d aS SERB EAeGH SeanecCoseSs -O11 01 
Cost per square yard (cents): 
iBiitMNimousimatenial =. =. 5225s. 22554 -hoe bee totes 3.00 1.71 1.65 1.92 
Gre Willen sod snl Gaeeerbosenone Hon suebeuboceccobonades 2.93 8 O77 | SOAS R Seca A) CBOSS Beet 
Retest ersten a aad te aiarsicla alo eras aia) emis cmcine Seaton sab etciiem ce | aaaiseacel ees 2.86 2.76 
Cleaminsistalace a= apee aaa =e a ee eee -27 -07 -08 -05 
IERIE inv IGinhl by. 6 8 s6cbere seeeocencecuaccs= Sheeed Base Secdececc 41 59 - 82 
Applying bituminous materials........-......-.... 16 29 e381 . 22 
Applying sand or gravel......--.-.---------------- 22 -26 .22 - 30 
STSRINFRIOO). scoadceceorsesed sscosceacoescsssocbesos - 22 32 24 . 24 
PRG L AN semen e sicid sates yee ets o siniais oes eae Siatcla> 6.80 6.33 5.95 6.31 
TaBLE 54.—Surface maintenance cost of experiments on Rockville Pike to December 
31, 1916. 
Total cost Surface | Total cost | Surface 
persq. yd.| mainte- of surface mainte- 
Experiment No. - Length. Area. rior to nance per sq. yd. nance 
ec. 31, | per.sq. yd. | to Dec. 31, | per mile for 
1915. during 1916.) 1916. year 1916. 
Feet 8q. yds Cents. Cents Cents. 
5 , L00 27.7 5 32.96 $462. 88 
4, 425 7,375 18. 89 6.83 25.72 601. 04 
7, 400 12, 333 20. 42 6.87 27.29 604. 56 
7, 100 11, 833 15. 21 2. 41 17.62 211. 20 
6,775 11, 292 15. 32 2.21 17. 53 194. 48 
6, 325 10, 542 27.53 1.34 28.87 117.92 
6, 689 11,148 20. 41 6.87 27. 28 604. 56 
