MICHIGAN ROADS AND FORESTS 



Specifications for 



Asphalt Pavement 



(Continued from page 3) 



that the voids will not exceed 25 per cent. 

 This 25 per cent, must be filled by asphaltir 

 cement. The average specific gravity of the 

 sand will be 2.6. The average specific gravity 

 of the asphaltic cement will be 1. The stan- 

 dard percentage of asphaltic cement is 10.0 for 

 light traffic streets and 10.5 for heavy traffic 

 streets. Nine per cent is a low minimum and 

 11 per cent a high maximum. 



As asphalt pavement is not laid as a matter 

 of municipal improvement but as a means of 

 exploiting the abutting property owner and 

 mulcting him in liability for special assess- 

 ments, it is deemed necessary to require a 

 "maintenance bond." This is a two-edged 

 sword, cutting the property owner both ways. 

 The surety is an approved bonding company. 

 This company charges a premium. The con- 

 tractor adds this premium to his bid. The 

 property o.wner complains of the high cost of 

 the pavement. He is told of the high cost 

 of the surety bond and maintenance. A poor 

 pavement is laid under the common wide- 

 open specification. The property owner com- 

 plains of the quality of the pavement and the 

 city engineer and board of public works tell 

 him that it makes no difference as the paving 

 company is under bond to maintain the pave- 

 ment ten years. The pavement disintegrates 

 in two years. The property owners complain. 

 Then ensues an eight years' game of hide and 

 seek between the paving company and four 

 succeeding boards of public works. In the 

 meantime the pavement is a series of bumps 

 and holes and the city has paid several judg- 

 ments for damages for personal injuries there- 

 on. 



The essentials of a good asphalt pavement 

 are as follows: 



1. A solid, well-drained sub-base. 



2. A base of well-graded Portland cement 

 concrete with a minimum thickness of six 

 inches. 



3. No binder course. 



4. Asphaltic cement of the following prop- 

 erties: (1) Minimum ductility of 15 at 77 deg. 

 F. (2) Penetration adapted to climatic condi- 

 tions. A permissible variation of five points. 



5. A surface coat of two to two and one- 

 half inches thick of the folowing grading: 



Light Heavy 



Traffic. Traffic. 



Pet. Pet. 



Asphaltic cement 10.0 



Sand and filer passing. .200. .. .10.0 



Sand passing 100 



Sand passing 80 



Sand passing 50 



Sand passing 40 



Sand passing 30 



Sand passing 20 



Sand passing 10 



The asphaltic cement will bear a variation 

 of one-half per cent., but should average as 

 above. The sand grading should conform to 

 the above standard in average. It will permit 

 a variation of 2 per cent, on the sieves passing 

 the larger amounts and of 1 per cent, on sieve- 

 passing the smaller amounts. When such a 

 pavement is laid a maintenance bond is super- 

 fluous. 



.10.0 

 .10.0 

 .24.0 

 .12.0 

 .10.0 

 . 8.0 

 . 6.0 



THE 



PORT HURON 



GENERAL 



PURPOSE 



ROLLER 



' 



PORT HURON ENGINE & THRESHER CO., 



MORE ROAD REWARDS. 



At the coming session of the state legisla- 

 ture, the state highway department will make 

 an effort to have the state road reward law 

 amended so as to allow the department to 

 pay rewards m six miles of road in each town- 

 ship annually, instead of two, the present le- 

 gal maximum. 



The great progress in state road building 

 makes the amendment necessary and the fact 

 that Wayne county will do a tremendous 

 amount of road work during the next few 



years is cited as one important example. In 

 many districts of the state, several of which 

 are in the upper peninsula, long roads have 

 been built, reaching cities in two or more 

 counties. The fact that counties only receive 

 a portion of the reward due them each year, 

 certainly hampers their road improvement 

 programs. 



During his recent inspection tour of the 

 upper peninsula, Deputy State Highway Com- 

 missioner Rogers found more than one in- 

 -.lauce where the state was unable to pay the 

 counties the full rewards on accepted roads. 

 If the law is amended the department believes 

 ood roads movement will be unrestricted 

 even in counties where big appropriations 

 have been made for building schedules of an 

 exceptionally large nature. 



SAVES $25,000 A YEAR. 



During the seven years of its operation the 

 municipal asphalt plant has saved Detroiters 



$174.866.18. Furthermore, the saving is in 

 creasing each year. 



Detroit's asphalt plant has always been 

 source of interest to other municipalities. It 

 operation has been watched closely by expert' 

 and the exceptionally favorable showing mad 

 last year promises to attract widesprinR ai 

 tention. 



While the lowest average contract price fc 

 resurfacing at the time the city took over th: 

 work was $1.23 per square yard, the averag 

 cost to the city under municipal operation w3 

 $].1105. Repaying and patching averaged n 

 spectively $1.30 and $1.12 under private cot 

 tract, while the city was enabled to perfon 

 the work for $1.0496 and $.9313. 



Something like 13 miles, or 262,964.78 van 

 of asphale were laid during 1910, at an e; 

 penditure of $287,295.64. 



