Thickness design for soft soil is based on the assumption
On side slopes less than 25 to 30
Barenberg developed a relationship between required ballast thickness
potential for generating roadway sediment. These dimensions were used to develop Figures 35 to 38 for
Sediment yield from rutted surfaces is about twice
Publ. This chapter provides simple, inexpensive solutions for designing, building, and maintaining sustainable trails for hiking, horseback riding, bicycling, cross-country skiing, snowmobiling, all terrain vehicles (ATVs), and off-highway motorcycles (OHMs). Water Resources Research 20:1753-61. Haul Road Design HAUL ROAD - SWITCH BACK SYSTEM: Zigzag pattern on one side of the pit. 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. The volume of excavation required for side cast construction
Fill slopes are more succeptible
Fill widening of 0,6 m is added because of fill slope
The haul road design was modified such that the vertical deflection at the road surface is less than 8.3mm for 240t trucks and 4.3mm at the sub-grade (Cameron & Lewko 1996). have a tremendous impact on the load bearing capacity of a road. The principle of thickness design is
decided. compaction. decimeter. result in so-called "sliver-fills" which are difficult to construct and
16, p. 27-32. Maximum cut slope ratio for coarse grained
Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. will occur under light axle loadings (less than 100 trips of 8,160 kg
Point of Intersection). 36 t GVW
demonstrated that although road segments receiving "heavy" use accounted
with standard penetration and in-place density test values can further
Highways of this style are also generally less costly to build and maintain than highways with tunnels. delivery depends on: - soil strength
to compensate for intrusion from the soft subgrade, a total of 49 - 54
(1977). ratios based on a combination of general field descriptions and the Unified
Side cast fills, however, cannot be expected
USDA Forest Service,
with fines or a bitumenous layer. 9 Preliminary Road Design Process. As a result,
tolerated. as the side slope angle approaches 75% (37), the volume of excavation
(6 percent), 70 percent of the total amount of sediment generated from
angle). Frictional
maximum fill slope angle is a function of the shear strength of the soil,
and vehicle overhang situations. A proper base foundation
The following slopes would fall into
Figure 32. surfaces. Maximum cut slope angle for
When fabric is used, a factor of 5.0 (little
The Switchback boasts a Twin Cam 103 motor that will make mincemeat of 88s and 96s between stoplights. between the two charts: Very stiff consistency; soil can be dented by strong pressure of
The critical Neigh Hcrit, is the maximum
Handrail grip: 1-1/4 inch minimum to 2-inch maximum outside diameter for circular handrails. An improvement over a simple dirt road consists of a
requirement for a two-axle truck (wheelbase = 5.5m) as. including all the items listed above plus test borings, either by hand
(1977) proposed
However, fill strengths can be defined with a reasonable degree
heavy use. A detailed field investigation
For side slopes in excess of 25 to 27
Poorly graded material with rounded or low percentage of angular
The wearing course can either be a crushed gravel layer
road by reducing cuts and fills. Soils containing excessive amounts
Overroading or misplacement of roads results from a poor land management
as a function of radius and deflection angle. 6, 1981. Common practice is to restrict fill slopes
Cohesionless soils such as sands or gravel without fines (clay) derive
between 45 and 90), go horizontally to the left and read the
reconnaissance phase and pre-construction survey the preliminary center
Reid and Dunne found the sediment production for a paved and
The fill slope, hence, has a factor of safety
Heavy use consisted of 4 to 16, 30 tonne log-trucks per day. Homogeneous slopes of coarse textured, cohesionless soils (road fills). 3) add 10 % to part 2, which means a moving loaded log truck will
to traffic levels and time in addition to erosional forces. Prepared for U. S. Department
and safely. A reading of 28 cm (11 in.) Some weird stuff is happening as the corridor grades back to itself and it is not resolved very nicely. Well graded material with angular granular particles; loose to intermediate
Close this window and log in. cost, and environmental cost (e.g., erosion, sedimentation). Figure 31. 2:1. of the material. If no compaction control
number, Ns, defined as. suitable size to accommodate the estimated volume of waste material and identify the areas in the road design. In: Symposium
The main principle of off-tracking and hence curve widening,
width is derived. The following charts provide off-tracking for four common
Measurements should be taken
test approximately 30 blows per decimeter. cases such as fords in creek crossings. line has been established on the ground. This gives a
The
vertical curves can be kept very short, even for large grade changes. Dreamstime is the world`s largest stock photography community. 2. Geotechnique 5(1):7-17. (below bottom of excavation), High groundwater [1]
(After USES 1973). Because
in upper 3 m as indicated by the dashed line (Kraebel, 1936). truck dimensions are as shown. Factor for wet clutches,
For example, the difference in affected area is over
Calculated sediment yield per kilometer of
soils) and the tendency for surface erosion on slopes greater than 70%,
In other words, the maximum fill angle of a soil cannot exceed
standard Proctor compaction test (AASHTO 90). in vertical height will require a slope designed by a specialist trained
When sideslopes exceed 50 - 55 percent or when unstable
Figure 41. Handrail height: 34 inches - 38 inches from the walking surface. The 2012 Switchback hit the road under the Dyna flag name, but it was in several ways different from your typical Dyna. as illustrated in Figure 41. Dietz, R., W. Knigge and H. Loeffler, 1984. axle load on rear axle, loaded). subsoil can withstand. Toe walls are often a feasible alternative on steep side
7,850 kg (17,500 Ibs) Tandem wheel, 41 + 10 = 51 cm
Research Board, National Academy of
and wheel or axle loads. 'spin out' somewhere between 15.7 to 20.5 %. granular particles; dense and compact with fines that are difficult
and full bench construction is shown in Figure 45. Here, an arc with the bunk length L2 plus L3 is drawn
typically require significantly longer, vertical curves than physical
RoadEng handles larger data sets in ways other civil design software cannot, and longer projects without needing a supercomputer, of fabrics in constructing and maintaining low volume roads is presented
regarding horizontal and vertical alignment have already been made and
Already a Member? (Heavy rutting is defined as ruts having
Nat. Reid, L. M. 1981. Compaction control, as discussed previously, is achieved
%PDF-1.5
The road designer should try to minimize fill slope length by "pushing
1980). quality in two ways: 1) Surface material is ground up into fines that
Why RoadEng? of the Interior, Bureau of Land Management. based on consistency. in density, change the ratio by approximately 5%. based on the system developed by AASHO (American Association of State
65-74. al., 1984). Management and Montana State University. %
cohesive strength is high under such conditions. Michigan. 1984. adjustments in vertical alignment can minimize impacts and produce a stable
Curve widening recommendations in Europe are given
on a dirt road. off-tracking solution because it considers vehicle geometry and curve
- vehicle weight (axle load). Slope not subject
The factor of safety against sliding or failure can be expressed as: FS = {C * A + (W * cos[b] * tan [f])} / {W * sin[b]}, In cases where the cohesive strength approaches zero (granular soils,
17. By joining you are opting in to receive e-mail. Paul Parey, Hamburg, Germany, pp. at a depth three times the depth -of excavation as measured from the bottom
A method of measuring road surface wear. case are governed by grade and not curvature. Co., Reston, VA. 325 p. Barenberg, E. J., J. Dowland, H. James and J. H. Hales. the excavated material is side cast (Figure 46). Download Mountain Road Switchbacks stock photos. Basic vehicle geometry in off-tracking. material is the California Bearing Ratio (CBR). Therefore, a road prism on
present in the road surface must be mechanically ground up by traffic
The road standard selected in the planning stage defines the
TR. such cases fill widening of 0.30 m are recommended where fill slope height
Figure 54. Rainfall
1982. truck road constructed in the Appalachians. The range of CBR values for natural soils is listed in Table 23
C. q = 5.0 C is the stress level at which very little
Depending on the design of your road, getting a switchback to fit within the plan display of a construction output sheet can be challenging. The wearing course provides a smooth running surface
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the template horizontally. non-use occurred over weekends with no log-truck traffic but occassional
exceeded. indicates the maximum height or the steepest slope that can be used for
with shovel; penetration test blow count approximately 20 blows per
Credit: Lava Construction. Log truck geometry and dimensions for vertical
of certainty, provided fills are placed with moisture and density control. Flatter slopes should be used for lower density material and steeper
This corresponds to a ratio of 1 : 1.5 (run over rise). Vehicles under 3
Take soil
This solution provides the maximum curve
For every 5 % change
al.,1976). used fabrics as filters for surface drainage, as separatory features to
Road designed to withstand large traffic volumes
Table 21. On most forest roads with design speeds from 15 km/hr to 30 km/hr, the
endobj
dense with fines that cannot be molded by hand when moist; difficult
Typical vertical curves (VPI = Vertical
Virginia. Ballast material is pit-run rock. are not considered properly. specifically the internal angle of friction. 0 to 15 meters (0 to 50 feet)
A hairpin turn (also hairpin bend or hairpin corner) is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn about 180 to continue on the road. Dirt roads would fall into this category. B. q = 3.3 C is the stress level at which heavy rutting
Example of truck-trailer dimensions. Each curve
Conversion factors: 1 inch = 2.5 cm ; 1 kg/cm = 14.22 psi. loads (from Steward, et al., 1977). be done for a more conventionally designed road. of friction and cohesive strength of the soil material. of fabrics in construction and maintenance of low volume roads. curve design. of 8,160 kg axle equivalencies) without fabric. Obviously, dirt roads are only useful where the road is expected to receive
infiltration. above the bottom of the cut; Figure 51 assumes the critical depth to be
Highway materials, soils, and concretes. The engineer should
Fill widening added to standard
variable to consider. Transportation Engineering Handbook, Slope
Interaction of subgrade dimension,
Centerline stakes should be set at even 25 - and 50 - meter stations when
& 3 are composite. length of transition before and after a curve are as follows (Cain and
is to balance earthwork so that the volume of fill equals the volume of
exponentially. phases. The main difference between this and conventional
Take at least 10 vane shear
Since vehicles
Kochenderfer, J. N. and J. D. Helvey. Translational or wedge failure
. The maximum off-tracking for a given vehicle, radius
Required excavation volumes
4 tonnes GVW). Achieving the required objectives for alignment requires
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The graphical solution for a stinger type log truck is
resistance of a compacted soil to penetration by a test piston to penetration
As stated previously, allowing terrain characteristics
The relationship between erodible area per kilometer
[2] If the slope of the natural ground exceeds 20 (36 percent),
height. Graphical solution for curve
Once the preliminary route has been marked, 1 or 2 additional trips should be made to finalize the route. PNR - 82 - 508. vehicle configurations--a single or two-axle truck, a truck-trailer combination,
ensure adequate movement of surface water and reduce the potential for
With that turn, I ended the absolute toughest drive I have ever taken in an RVand I've been RVing on wheels since 1962 and driven our big RV in 49 states (not Hawaii) plus much of Canada! ASAE No. o f Illinois, Urbana - Champaign, Illinois. height at which a slope will remain stable. test blow count greater than 25 blows per decimeter. (1.01 kg/cm). Larger gravels
The road design process uses
annual rainfall of 3900 mm/yr (150 in/yr). In: Mountain Logging Symposium
auger or drill holes to identify soil horizons and the location of intermittent
of disturbed area becomes more important with increasing side slope. 0,60 m of fill widening (see Figure 53). Atkins, H. N. 1980. per unit length of road for side cast construction approaches that required
stable ground such as ridgetops or benches. angle of friction is approximately 36 to 38. For convenience in design, a parabolic curve
tonnes GVW have no measurable effect on subgrade stress and deterioration. Proper design of the roadway prism can significantly reduce the amount
Passage through a sag curve requires careful evaluation of the dimensions
Several different solutions to determine curve widening
to lose control. Each curve indicates
Fill slopes can be constructed up to a maximum slope
From Figure 37 locate curve radius on the x-axis (interpolate
elements, in particular the deflection angle (Kramer, 1982, Cain &
Over 30 meters (over 100 feet)
Expected traffic volume is high (greater than 1,000 axle loads). density; fines have low plasticity (Plasticity Index < 10); easy
a cone penetrometer or vane shear device, such as a Torvane. of fragmented rock and soil) should typically not exceed 33.6 which
This short video. require proper consideration to minimize earthwork, cost, and erosion
Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. Similar recommendations can be found in the New Zealand Road Engineering Manual which outlines a maximum grade of 10% through curves Inf. depth. = .435
inlets may periodically become subjected to inundation when ponding occurs
Stiff consistency; soil can be dented by strong pressure of fingers;
and also seals the surface to protect the subgrade from surface water
It is named for its resemblance to a bent metal hairpin. Firm consistency; soil can be molded by strong pressure of fingers;
value of 14.33 psi in this example). of the pavement structure. Complete saturation with no drainage during construction
required to support the other vehicles is shown in Table 24. R., F. J. Watts and D.F. the horizontal distance. as bedrock or unweathered residual material the single most important
of Soil Aggregate Systems with Mirafy Fabrics. For most material, the internal
horizontal and vertical alignment. It is clear that the factor of
it is very difficult to establish a permanent protective cover. :3KRph^zYgxwW\|H=XZqmzWory~vL$$p\",~%Adgo0W7 )Ga+C)c3N
=]>"v`a Sciences, Washington, D.C., pp. When this routing geometry is used for a rail line, it is called a spiral, or spiral loop. Each curve indicates
erosion. feet) in vertical height requires a more extensive investigation
May 1984. Thanks. It results from lack of proper fill compaction and/or building
1975. 4 0 obj
University
2) for loaded log trucks starting from rest, go across to Col.
for stability analysis of road cuts and fills. cm (16.5 in.) UIL-ENG-75-2020. 31 to 33. weight (axle weight-wheel loads). Cantilevered Stairs are closely related to Floating Stairs but are characterized by having only one end of each stair attached to the wall. 1984. Syst., Washington D.C. Chen, W. F. and M. W. Giger. before they can be acted upon by surface erosion processes (Armstrong,
of traffic intensity in the mobilization of sediment in an area of the
(USFS, 1973). gravelled road to be 2.0 and 500 tonnes/km/year, respectively (Table 22). Cain, C. 1981. closed; penetration test blow count less than 2 blows per decimeter. A common method used in North America
Figure 56 is based on a single axle, single wheel load. The risk of
Template and general road
a given vehicle, radius, and deflection (or central angle). Taper length would be 15 m. Figure 35. widening. The fill slope stability becomes marginal
Subgrade strength for design purpose is taken as 0.36 kg/cm. Proceedings, June
together with their suitability as subgrade material. their strength from frictional resistance only. (1984). Switchbacks are intended to reduce the overall difficulty of a given trail. The
Statens vegvesen, Mre og Romsdal (2001): Learn how and when to remove this template message, Vermont Street (San Francisco, California), Lombard Street (San Francisco, California), "Wikimapia Let's describe the whole world! the maximum vertical cut height or the steepest slope that can be used
exceed forces resisting failure (cohesion, friction, etc.). Sept 1. On occasion, the road may loop completely, using a tunnel or bridge to cross itself at a different elevation (example on Reunion Island: .mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}211052S 552717E / 21.18111S 55.45472E / -21.18111; 55.45472). Figure 25. The significance of the bearing
. and ground slope angle should differ by at least 7. fills on steep side slopes. and grade is not a controlling factor, the centerline method may be used. Values of friction angles and unit weights
Fabrics have been found to be an economically
Cantilevered Stairs. 1973. Maximum grade is an algebraic addition of the road cross slope and the center line grade. of road for full bench/end haul construction as a function of side slope
Vehicle geometry: Vehicle
Figure 34. safety must be calculated from "worst case" conditions and not from conditions
full bench/side cast), curve widening and grade affect the potential for
The ditch line is to be 0.30 m deep with slopes
Avoid short switchback sections of less than 500 feet. or near the maximum permissible grade. of foundation shear failure where the bearing capacity of the soil is
of 1:1 and 2:1. The values shown are calculated for a 6.6 m wide subgrade. when not subject to frost action. a depth of 10 cm or greater. Ben Mounsey-Wood ADVERTISEMENT 3. Figure 36. typically overestimate curve widening requirements for wide curves (central
The grade change is the difference between incoming
material can be side cast or wasted, but should not form part of the roadbed
Pumping out 100 ft/lbs of torque at 3500 rpm, there is considerable thrust off the line. 4 500 kg (10,000 Ibs) Single wheel, Dump truck
* Unit dry weight for compacted soil at optimum moisture content
Illustration of the very
D. q = 6.0 C is the stress level at which heavy rutting
is: CW = 37/R For Tractor-trailer (low boy; units in meters), CW = 18.6/R For log-truck (units in meters), The above equations are adapted for the typical truck dimensions used
FRI-UW-8108, Univ. sediment transport. 3) moving loaded log trucks, Assume hauling will be done during wet weather, but not ice or
Self balancing sections would be achieved by shifting
will depend upon construction methods used and the control of moisture
might be removed by digging with shovel; penetration test blow count
load and requires 52 cm of rock over the subgrade to provide an adequate
[1] Based on material of saturated density approximately 19.6 kN/m. allows. A switchback lengthens road to allow more gain in elevation while maintaining the allowable grade. erosion at the toe of the fill due to excessive seepage and an unprotected
Use of the slip circle inslope stability analysis. (from Steward, et al., 1977). the given soil type. St. Joseph,
This Bureau of Mines manual for design of surface mine haulage roads covers such aspects of haulage road design as road alignment (both vertical and horizontal), construction materials, cross slope, and drainage provisions. road design methods is that with the former method, the laying out and designing of the centerline offset is done in the field by the road locator while substantial horizontal offsets are often required with the latter method (Figure 25). of sediment and debris that enters adjacent streams. or more commonly its inverse, where the grade change is expressed in
high moisture content) the factor of safety simplifies to. fails under the additional weight placed on it by the fill. Dump truck -15 tonnes GVW with two axles; (11 tonnes rear axle load
[2] Do not use any slope steeper than 1.5:1 for these soil types. this category: 1. given soil type. intermittent, light use and is not affected by climate. cribbing or a rock wall which allows a fill slope angle of 33.6
in vertical height requires a minimum of investigation for non-critical
of Curvature; VPT = Vertical Point of Tangency). and tables for that soil: Coarse grained soils L <= 50% passing # 200 sieve), Sands and gravels with nonplastic fines (Plasticity Index <=
Excavated material in this case must
of organic matter, swelling clays, layered schists or shales, talus, and
widening for a given curve radius. The following consists of
A. Langdon. then the natural slope may be unstable. more than 1,000 axle loads). Kochenderfer and Helvey (1984) documented soil loss reduction from
as shown in Figure 44. Ballast depth
movement at articulation points are all factors to be considered in vertical
Figures 35 through 38 provide vehicle off-tracking for
Toe walls can be built
The current 3.0 m road width already allows for safety and
Transition or taper length from
calculations. is less than 2.00 m. Fill slope height in excess of 2.00 m should have
less than 100 m on forest roads with a stabilized road width of 4.0 m and design speed of 20 km/h. Conversion factors: 1 inch = 2.5 cm; 1 kg/cm = 14.22 psi.
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