CONSTRUCTION NOTES 257 



(b) Tanbark walks (excavation}. If tanbark walks are constructed on 

 a gravel foundation the same principles for excavation apply as are out- 

 lined in the foregoing paragraphs under la. If tanbark walks are con- 

 structed on a sand loam foundation then the same principles for excavating 

 apply as are outlined under ic in the following paragraph. 



(c) Turf walks and woodland trails (excavation}. In the construction of 

 turf walks and woodland trails there are two principles of construction to be 

 kept in mind with reference to the excavation for foundation. Woodland 

 trails are usually constructed in a most inexpensive manner, accepting the 

 natural soil, with or without surface and subsurface drainage, and there- 

 fore there is little or no excavation unless it be necessary in order to procure 

 easier gradients or cross-slopes. Turf walks may be constructed in con- 

 nection with refined formal gardens and lawn areas and subjected to inten- 

 sive traffic. Turf walks under such conditions vary from woodland trails 

 in that the problems of surface and subsurface drainage require careful 

 study. Where the natural soil is heavy clay or clay loam an excavation 

 should be made as for a gravel or hard surface walk and of sufficient depth 

 to provide for a foundation course of cinders (6 inches deep) and a wearing 

 surface of sandy loam (6 inches deep). On natural sandy loam soils this 

 excavation is unnecessary. 



(d) Stepping-stone walks (excavation}. The excavation for stepping- 

 stone walks is usually confined to an area covering the full width and length 

 of the proposed line of stepping-stones, especially where the stepping-stones 

 are in larger units (20 to 24 inches square) and laid with a distance of two 

 to four inches between individual stones. (See figures 6 and 6A, Plate 112.) 

 If the individual stepping-stones are in smaller units (18 to 20 inches square 

 and less) and spaced at greater intervals than four to six inches (see figure 7, 

 Plate 112) then the most economical method of completing the excavation 

 for the foundation of such walks is to first space the stones on the finished 

 grade of the walk and then to excavate, to the proper depth, only that 

 portion of the soil directly beneath the individual stones. 



(e) Board walks (excavation). Inasmuch as board walks are either of a 

 temporary character to tide over the requirements of traffic until a perma- 

 nent walk can be constructed, or are constructed for use in summer colonies, 

 especially along the beach where inexpensive construction is desired, there 

 is no problem of excavating for the foundation of such walks. 



Variations in specifications for excavating walks under varying conditions 

 of soil and climate. In the southern latitudes where there is no frost action 

 the problem of excavating for a foundation is not important. Under such 

 climatic conditions excavation is necessary only in clay soils, for drainage, 

 and is not necessary in sandy soils except to sufficient depth to provide 

 space to construct the wearing surface. 



