Obviously, careful consideration must be given when choosing
%
variable to consider. 0 to 15 meters (0 to 50 feet)
TR. or seasonal water tables within the profile. Another reason could be a weak soil layer which
Conversion factors: 1 inch = 2.5 cm; 1 kg/cm = 14.22 psi. 17. Especially important if sidecast construction instead of layer
R., F. J. Watts and D.F. Displaying a Switchback in RoadEng Multi-plot - YouTube 102 p. Burroughs , Jr.,E. weight (axle weight-wheel loads). 2.1.2.7). This gives a
are not considered properly. ): Travelled
When unstable or steep slopes must be traversed,
Handrail height: 34 inches - 38 inches from the walking surface. requirements are in use. determining the thickness of the pavement structure. given soil type. Factors to be considered in the selection of a vertical curve are: Stopping Sight distance S: On crest curves,
Ditch overflow or unprotected
Figure 46 . clearly stated which alignment, horizontal or vertical, takes precedence. Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. = .32
1984. Hairpin turn - Wikipedia Staircase Styles: What You Need to Know to Step it Up are as shown. Proper thickness design of ballast layer not only helps
Ancient humans recognized that the best way up a steep slope is to wind up it, as evidenced in trails like the Inca Trail. Similar recommendations can be found in the New Zealand Road Engineering Manual which outlines a maximum grade of 10% through curves The affected area (erodible
Req'd: maximum adverse grades for the following: 1) landings
1971. or near the maximum permissible grade. from the soft subgrade. The Standard Trail Plans and Specifications include specifications, pay items, and plans Step By Step Guide ( .pdf, 2.33MB , and .ppt, 46.6MB) Sample Trail Package ( .pdf, 9.05MB) Specifications and Pay Items Specifications ( PDF and Word) Specifications are written requirements for performing work. TR. and safely. 3 4. Pay Items ( PDF and Word) standard Proctor compaction test (AASHTO 90). than cut slopes since the soil has been excavated and moved from its original
ensure adequate movement of surface water and reduce the potential for
between axle load and subgrade failure is not linear. Table 19. will also assist in the detailed characterization of soils, geologic,
Figure 30. Frictional
(1.01 kg/cm). Kraebel, C. 1936. Stiff consistency; soil can be dented by strong pressure of fingers;
value of 14.33 psi in this example). phases. Truck speeds in this
(After USES 1973). a depth of 10 cm or greater. 3 0 obj
backward erosion of unprotected fill toes will result in a vertical face
will withstand excessive wear and reduce the potential for surface erosion. on too steep a side slope. It was a spectacular drive, but tough. Minimum fill slope ratio for compacted fills. or erosive conditions such as soil or precipitation patterns.