WALKS 



WALKS 



3499 



3981. Branching of road. 



By tying, colored twine around the stakes and moving 

 it" up and down while sighting, the new grades may also 

 often be visualized. In cleared ground this method is 

 very sure. It is better than the engineer's method of 

 regular curves connected by straight tangents. 



Precaution should be exercised at curves and inter- 

 sections to secure safety as well as appearance and con- 

 venience. The fast-moving almost noiseless modern 

 vehicles emphasize this precaution; therefore the view 

 ahead at sharp turns should always be unbroken by 

 banks or dense, tall plantings (Fig. 3980). Drives 

 should branch on the outside (A) not inside (B) of 

 curves (Fig. 3981). Danger lurks in narrow branch- 

 ings and may be avoided bv widening the intersect- 

 ing triangle (Fig. 3982). Small' 

 triangles at right-angle in- 

 tersections are not to be 

 advised. When used at all 

 they should be large and 

 clear of tall planting which 

 obscures the view. Triangles 

 with less than 50-foot sides 

 mav better be omitted alto- 

 gether (Fig. 3983). 



At the turn-in from the 

 public road especial care must 

 be exercised to avoid danger. 

 The acute angle (A) is bad 

 (Fig. 3984), and the corner 



3983. Driveway with and without an undesirable triangle. 



entrance (B) is not 



much better, or is absolutely fool-hardy when arranged 

 as C. The best turn-in is shown at D. When pos- 

 sible, enter from an outward bend of the public road 

 (Fig. 3985) or at the head of the street (Fig. 3986), and 

 always at nearly right angles to the public road (Fig. 

 3980), making a gradual bend, if desired, to an angle 

 within the property. Avoid if possible the street 

 entrance at the foot of a steep hill as it is the point 

 of greatest speed. Formerly entrances were heavily 

 emphasized by gate-piers, lodges, and tree-plantings; 

 now they are recessed and the planting is less high. 



The road-surface should be smooth, dry, elastic, 

 clean, and of good color. All this is to be obtained by 

 various constructions. The gravel roadway is always 

 pleasing as to color and wear, but the present-day 

 macadam, although somewhat lacking as to color, 



3982. Widening the intersecting 

 angle of a road. 



better withstands modern traffic. Brick, concrete, and 

 asphalt are too noisy and seem too hot and formal for 

 private roads in the country, although for short dis- 

 tances in the city they may be used properly. 



The construction of any roadway is begun by grad- 

 ing the level for the bottom of the road. This is called 

 the sub-grade and is made higher in the center than at 

 the sides by J- inch or more to each foot width. The 

 sub-grade should be rolled before the stone is laid. 

 For private drives generally a light Telford consisting 

 of native stone, about 6 inches wide and 1 to 3 inches 

 thick, is laid by hand upon 

 edge crosswise of the road. 

 Over this a sprinkling of 

 clay soil is thrown and cov- 

 ered 2 inches deep with 

 crushed stone of the IJ^-inch 

 grade; this in turn is covered 

 by an inch of crushed lime- 

 stone screenings. Each 

 course as laid is sprinkled 

 and rolled with a six- to ten- 

 ton steam roller. This is a 

 water-bound macadam. (Fig. 

 3987 A.) Since it does not 

 withstand automobile traffic without dust, various 

 oil-binding treatments of the surface are on the market. 

 Bitulithic macadam is an excellent method of binding 

 the top courses together, with hot pitch applied under 

 pressure. There is no tracking of oil when this method 

 is practised and the color and texture are satisfactory. 

 Local conditions so influence materials and methods 

 that it is necessary to investigate before applying any 

 general specification in detail. 



A cheaper road (Fig. 3987 B) may be built of spawls, 

 or other broken stone, spread evenly, rolled, and 

 surfaced with the other two courses of crushed stone, 

 each thoroughly rolled wet. Where gravel of a cementi- 

 tious quality is obtainable, or a hard shale, it may be 

 substituted for crushed limestone surfacing. 





3984. Good and bad entrances from the public road. 



3985. A good entrance from an outward bend of the road. 



