ROAD 



ROADS AND ROAD-MAKING 



C. O. Harper, Author, The Great North Road, and A. Williams 



Articles on allied subjects .include Inn; Motor Car; Transport. 



See also those on Icknield Way ; Wailing Street, and other Roman 



roads ; Britain, with map ; Highway ; Surveying, etc. 



Early literature, including the 

 Bible, contains many references to 

 roads, which are a necessity to even 

 a rude civilization. The ordered 

 might of the Roman Empire was 

 maintained only by the provision 

 of a well-considered scheme of 

 roads on the European continent, 

 and in Britain. There were four 

 great Roman routes in Britain, 

 Watling Street, Fosse Way, Ermine 

 Street, and Icknield Way. 



It is certain that these roads 

 were founded on already existing 

 rude tracks the Romans found 

 when they conquered Britain, and 

 that the quality of the work done 

 in reconstructing them was singu- 

 larly varied. Roman roads were in 

 general surveyed and executed 

 with such science and solid work- 

 manship that they have ever been 

 considered models to the more 

 modern road-maker. 



The classic Roman method was, 

 having laid out the line of road, to 

 trench either side, removing the 

 earth down to firm ground. The 

 trenching would go in advance, 

 while the excavation of the road 

 itself followed, down to the sub- 

 soil. A layer of fine earth, spread 

 over this and rammed hard, 

 formed the pavimentum. Squared 

 stones, generally bound together 

 with liquid mortar, represented the 

 next stage (statumen), followed by 

 a thicker mass of small rubble, 

 .mixed with lime (rudus). A fur- 

 ther stratum, known as nucleus, 

 was added, this being chalk, 

 broken tiles, and gravel , mixed with 

 lime and compacted by ramming. 

 The actual road-surface, the sum- 

 mum dorsum, was then laid. Its 

 composition varied, but the ideal 

 was cut stone, accurately fitted, 

 somewhat like the setts of modern 

 practice. The finest surviving 

 specimen in England is the road 

 over Blackstone Edge in Yorkshire. 



French and English Systems 

 While Roman roads are in 

 general straight, they are so only 

 within limits. They consist of a 

 series of alinements. But this 

 depended greatly upon the personal 

 practice of the various surveyors 

 and the peculiarities of the country. 

 Road-making decayed with the 

 fall of the Roman Empire. Already 

 when the Saxons came to Britain, 

 the roads had largely fallen into 

 disuse, and it was not until the 

 reign of George III that any 

 serious attempt was made to deal 

 with communications. This was 

 the great era of local Turnpike 



Acts, of which hundreds were 

 passed, providing for the mainten- 

 ance and remodelling of roads, the 

 cost to be met by tolls. The era 

 of the great road engineers then 

 followed. In France, Tresaguet 

 adopted the Roman system of 

 excavating and putting in a solid 

 foundation of large stones to sup- 

 port the successive upper layers of 

 smaller material ; but no cement 

 was used, and the surface con- 

 struction and upkeep left much to 

 be desired. 



In England John Loudon Mac- 

 adam attacked the problem of 

 providing a more durable surface, 

 and early in the 19th century intro- 

 duced his system of covering roads 

 with layers of hard stone broken 

 into cubical pieces, which under 

 pressure would jamb and become 

 consolidated. For the stability 

 of the surface he trusted mainly 

 to good drainage of the subsoil. 

 His successor, James Telford, who 

 remodelled the great London- 

 Holyhead road, followed Tresaguet 

 in insisting on the importance of a 

 strong foundation, but his sur- 

 facing method differed consider- 

 ably from that of Macadam. 

 Highway Construction 



Leaving town roads out of con- 

 sideration for the present, a sub- 

 stantially made modern highway 

 is constructed in a trench ex- 

 cavated to a depth of about 18 

 inches and bottom-rolled until it 

 is compacted everywhere, and has 

 a gentle slope from the centre to 

 both sides. If the Telford founda- 

 tion be used, the earth is covered 

 with large stones closely packed 

 and wedged so firmly that they 

 cannot move. Then follows a 

 layer of well-rolled broken stone, 

 thicker at the centre than at the 

 edges. The surfacing is usually 

 two layers of two -inch " macadam " 

 rolled down to a thickness of three 

 inches. A dressing of chips or 

 gravel is given to fill up interstices 

 and help to key the whole mass 

 together. 



If the more strictly macadamised 

 form be preferred, the foundation 

 consists of a layer or layers of 

 stones larger than those for the 

 top, and all the material is con- 

 solidated by the roller as put in. 

 Macadam entirely deprecated the 

 use of water in road-making, but 

 the modern methods of steam- 

 rolling exhibit a complete rever- 

 sion' of practice, and water is now 

 freely used, wrongly, as many con- 

 tend. It is, therefore, all the more 



ROAD 



necessary that, in this procedure, 

 a road should have a pronounced 

 camber, and that the side drainage 

 should be thorough. But acutely 

 cambered roads are most unde- 

 sirable for motor-traffic, especially 

 when pneumatic tires are used, as 

 they conduce to skidding. 



C. Q. Harper 



The economy of using hard 

 stone has now been thoroughly 

 recognized, the first heavy cost 

 being eventually more than re- 

 couped in the longer life of the 

 surface and the lessened need for 

 clearing and repair. Basalts, 

 syenites, and granite form the best 

 road-metal, and come largely from 

 the Glee Hills in Shropshire. But 

 even the best macadamised sur- 

 face is not equal to the disinte- 

 grating effect of fast motor- 

 traffic, which creates much dust 

 and in a very short time estab- 

 lishes " pot-holes." These, retain- 

 ing water, soon ruin the best- 

 made roadway. 



Methods of Surface Protection 



The problem therefore arises, 

 how to protect the surface and 

 through it the structure. This 

 has been met in several ways. 

 Spraying the surface with hot tar 

 and then sprinkling with fine gran- 

 ite chippings is an alleviative, but 

 it is a thin coating, soon worn 

 through. A more expensive sur- 

 face, but with a longer life, is 

 formed by using broken granite, 

 steel-furnace slag, and granite 

 chippings, coated with tar-pro- 

 ducts. This readily amalgamates 

 under steam-rolling, and is water- 

 proof. Various methods of laying 

 are employed. 



(1) The matrix, or binder, is 

 spread to a depth of three-quarters 

 of an inch, and the prepared stone 

 distributed over it in two layers. 

 Rolling follows till the matrix works 

 up through the interstices of the 

 stone. More binder is then applied 

 to the top and rolled in. Finally, 

 the surface is sealed by .a coating 

 of hot tar, sprinkled with fine 

 chippings. 



(2) The stones are spread first 

 and the matrix is added as rolling 

 proceeds, till a solid surface is 

 obtained. Sealing follows. 



(3) The stones are spread and 

 rolled well, and the matrix is 

 forced in afterwards. The sealing 

 is then done as mentioned above. 



(4) The stones are rolled and 

 grouted by pouring in hot com- 

 position mixed with sand or other 

 fine material. 



In all cases the object aimed at 

 is to obtain a surface at once 

 resilient and watertight. The first 

 cost per square yard ia considerably 

 higher than for water- bound 

 macadam ; but the upkeep cost 



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