COST, PERFORMANCE, AND ESTHETIC IMPACTS OF 

AN EXPERIMENTAL FOREST ROAD 

IN MONTANA 

Rulon B. Gardner 

This file was created by scanning the printed publication.

Errors identified by the software have been corrected;

however, some errors may remain.
THE AUTHOR 

RULON B. GARDNER is principal research engineer, stationed at the 

Intermountain Station's Forestry Sciences Laboratory in Bozeman, 

Montana. He has been involved in logging and road construction in 

National Forest Systems and Research for the past 22 years. 
USDA Forest Service 

Research Paper INT -203 

April 1978 

COST, PERFORMANCE,AND ESTHETIC 

IMPACTS OF AN EXPERIMENTAL FOREST 

ROAD IN MONTANA 

Rulon B. Gardner 

INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 

Forest Service 

U.S. Department of Agriculture 

Ogden, Utah 84401 
,, .:' 

RESEARCH SUMMARY 

A study on the Coram Experimental Forest in Montana was designed to 

assess the environmental impacts of harvesting and attendant road construction. The objective of the road portion of the study was to locate, design, 

and construct a road with reduced impacts (compared to standard practice) 

on the environment that would still serve the near-minimum needs of the 

projected traffic volumes, vehicle sizes, and logging equipment (skyline 

logging), and to evaluate the costs and impacts. 

A single-lane (14-foot (4. 27-m) finished surface with a 3-foot (0. 91-m) 

dtich) road was constructed along the general contour, turnouts were fitted 

to the terrain and were not intervisible, and landings were not constructed. 

Other selected design criteria were also used to reduce impacts. 

Skyline harvesting was accomplished from the single-lane road without 

undue difficulty, and it continues to serve traffic needs. Comparison of the 

road with adjacent, older forest roads incidates a major improvement in 

esthetic acceptability. 

A comparison of hauling costs with a double-lane road, using traffic 

volumes appropriate for the area (10 VPH, 1/2 logging trucks), showed 

costs would be about $2. 35/M bd. ft. ($0. 59/m3) higher for the single-lane 

road. 
CONTENTS 

Page 

INTRODUCTION . . . . . . . 1 

ROAD LOCATION AND DESIGN 2 

General Design Procedures . 2 

Experimental Road Design 3 

ALTERNATIVE DESIGNS, CONSTRUCTION, AND COSTS. 6 

Alternate Designs and Construction Cost 6 

User Cost . . . . . . . . . 8 

ROAD PERFORMANCE TO DATE 11 

Structural Features. . 

Drainage 

Clearing 

Erosion . 

Revegetation. 

Esthetics . . 

DISCUSSION AND CONCLUSIONS. 

PUBLICATIONS CITED • . . 

APPENDIX A 

APPENDIX B . 

11 

16 

17 

19 

19 

20 

21 

22 

23 

27 
f'.... CORAM EXPERIMENTAL FOREST 

Kalispell• "'-l 

\ 

Missoula e MONTANA 

I<EY MAP 

N....-

LEGEND: 

EX PER I MENTAL ROAD •••••• 

ABBOT BAS IN ROAD -- NO. 590. B ---

Figure 1.--Location and layout of experimental logging road on 

Coram Experimental Forest~ Montana. 
INTRODUCTION 

Forest managers face a paradoxical challenge of utilizing forest resources (primarily timber) without damaging or destroying other assets of the forest. Also, with a 

decreasing land base available for timber growing, more intensive forestry must be 

practiced in the future. These facts, along the trend toward logging steeper terrain 

and more fragile soils, increase the potential damage from timber harvesting and road 

construction. Hence, minimizing the impacts of road construction while still providing 

for harvesting and traffic needs is essential for continued resource use. 

In the past few years, more attention has been given to reducing road impacts, 

even though some of the trade-offs have not been very well defined. In the past, roads 

were designed primarily to serve the anticipated traffic needs of the access system. 

If traffic needs and user costs are the primary consideration, then often the environment suffers. Because so many forest roads must accommodate logging trucks, for safety 

and economic reasons roads of a higher standard (those incorporating extra width especially) have often been constructed at some expense to some, not well defined to date, 

environmental and social values. 

Information is seriously lacking to evaluate trade-offs related to social, environmental, and economic values associated with different road standards. Because of the 

paucity of information on which to base decisions, many research projects are now 

underway or are planned. This paper reports one such study on the Coram Experimental 

Forest in Montana (fig. 1). 

The broad objective of the road study was to locate, design, and construct a road 

with reduced impacts on the environment that would still serve the near-minimum needs of 

projected traffic volumes, vehicle sizes, and logging equipment, and to evaluate the 

costs and impacts. Some of the minimum road design criteria were set by the requirements 

of the logging and transport equipment. Small commercial running skyline systems were 

specified to reduce road width requirements as much as possible. This report evaluates 

road design, construction, and cost and compares costs to those of alternative designs. 

Also, observations of initial performance of the road and its esthetic acceptability 

are presented. 

1 
ROAD LOCATION AND DESIGN 

General Design Procedures 

Until the past few years, the environmental and social impacts of road construction 

were given little or no consideration. Road standards were concerned primarily with the 

geometric and structural features that would provide safe and economical transportation. 

These standards specified some or all of the following: 

--width of road x-section 

--width of clearing 

--grade 

--alinement 

--water control specifications (drainage) 

--consolidation (bearing strength) 

--surfacing. 

The principal differences among standards are grade, width, alinement, and surfacing. A so-called low-standard road is often thought to be associated with high 

environmental impact and a high-standard road with low environmental impact. (Often 

the results can be opposite to these assumptions.) A road standard, as the term has 

generally been used, should not be used alone as an indicator of impact--more information about a road is needed to judge impact. 

Recognizing the importance of topographical location, proximity to streams, and 

fragile soils, the environmental and esthetic impacts of roads can usually be mlnlmized by reducing road and clearing widths. Reducing widths accomplishes the following: 

--Reduces the area covered by the road x-section which in turn: 

--reduces the amount of cut-and-fill slope exposed to view, 

--intercepts less ground and surface water flow, thereby 

reducing potential hydrologic impact, and 

--reduces the potential for erosion. 

Other design features that reduce impacts are: 

--fitting the alinement to the topography to avoid large cuts and fills 

--providing adequate drainage for surface and subsurface flow 

--stabilizing subgrades and surfaces 

--stabilizing cut-and-fill slopes by vegetative and mechanical methods. 

The guiding criterion for the experimental road was to reduce impacts while still 

providing for the basic requirements of the traffic and logging equipment; therefore, 

width became the most important design feature to reduce exposed area and resulting 

impacts. 

2 
Experimental Road Design 

Objectives and Guidelines 

The road was constructed to provide access for an experimental logging study of 

the productivity of skyline logging under different silvicultural and utilization prescriptions. The principal guidelines and constraints were: 

--to reduce physical and visual impacts on the site and 

--provide access to the harvesting units for all traffic and skyline logging 

equipment. 

Within these guidelines, the major objectives of the study were to: 

--develop design criteria to reduce physical and visual impacts and 

--assess the environmental impacts and economic performance of the road. 

Location and Design 

The areas to be harvested and the new road constructed to provide access are shown 

in figure 1. Three cutting blocks 11, 12, and 13 were accessible from an existing road 

(Flathead NF road 590-B). The experimental road, an extension of road 590-B, was built 

to provide access to the other three blocks 21, 22, and 23. 

Planning and design for this road proceeded somewhat differently from a normal 

forest road because of the objectives. However, route reconnaissance and verification 

proceeded in a normal manner using access needs, available photography, and soils and 

geologic information. Whenever a skyline logging system is used and access starts from 

below the units (fig. 1), it is often advantageous to switch back on the terrain to 

gain the elevation needed for the skyline system. The locations found for the second 

and third switchbacks, shown in figure 1 and appendix figures 17 and 18, fixed the 

ruling grade for the primary climbing sections of the road from approximately station 

5+00 to 45+00. 

After the route was selected, the design phases proceeded differently than for a 

system road. Because the primary objective was to reduce impacts, especially esthetic 

impacts, road width was set at the width that would accommodate the tracks of the proposed yarding equipment (12.5 ft (3.81-m)), with a minimum extra width for safety, and 

a ditch was added for drainage--14-foot (4.27-m) finished surface, with a 3-foot (0.91-

m) ditch (app. fig. 19). Normally, a log-hauling cost analysis would be made at this 

point to assist in determining road width, curve radius, sight distances, and turnout 

spacing. Instead, the 14-foot (4.27-m) surface was used, and turnouts were placed 

where the terrain was favorable and are not intervisible as normally desired. As 

mentioned earlier, landings were not specifically designed, although it was apparent 

that turnouts and areas where curves were widened could be planned for use as landings. 

The following features were specified for the final design. 

1. Right-of-way slash was disposed of on the first 59 stations by chipping and 

scattering. The balance of the slash to station 105+19 was disposed of by burning. 

Traditionally, right-of-way slash has been burned. Burning, properly done, not 

only disposes of the slash, it also immediately returns nutrients to the soil. However, 

because the area burned is later incorporated in the road, the nutrient return value is 

questionable. If the job is not done properly, quantities of unburned material usually 

end up in the road fill. Either way, smoke from burning is objectionable. 

3 
An alternative method used for many years for powerline right-of-ways, especially 

in gentle terrain, is to chip and scatter the slash. To compare costs and results, 

this treatment was incorporated. 

2. Station 26+00 to 58+00--trees were cut selectively on both cut-and-fill sides. 

Removal on cut side as near as possible to cut without danger of slope failure; fill 

side a minimum of 8 feet (2.44-m) from road shoulder, or the branches trimmed to not 

interfere with traffic. 

Conventional clearing widths have traditionally extended 5 feet (1.52-m) back 

from the cut slope and minimum of the toe of the fill slope, both depending on soil 

and timber types and, in some cases, climatic factors. In order to reduce clearing 

widths to minimize esthetic impacts, the clearing widths were modified as shown. 

3. Station 49+00 to 58+00--subsurface conditions allowed for the use of 1/10:1 

cut backslopes. 

A seismic traverse was run over the entire route to assist in the design of the 

backslopes. The bedrock in this section was soft enough to rip, (seismic velocity 

4,000 ft/sec (1,219 m/sec)), but competent enough to stand on 1/10:1 backslopes. The 

objective was to reduce the amount of area disturbed by the road prism and the subsequent clearing necessary. Because the exposed rock sections (3/4:1 slopes) on the 

old road below had not revegetated in 20 years, opening up flatter slopes would appear 

merely to expose more raw slope to weathering. The steep slopes produce air-slacked 

material, but so do the flatter slopes. 

4. Turnouts were not intervisible. 

Turnouts were used when the terrain was favorable, thus keeping road widths down, 

to reduce impacts. Modern logging trucks are equipped with two-way radios that can be 

used to regulate traffic. This helps compensate for reduced spacing and reduces potential traffic dangers. (This road was closed to public traffic during the study.) 

5. Stepped backslopes were used from approximately station 79+09 to 83+53 and 

were planted to different varieties of shrubs or grass. 

Seismic velocities here (station 79+09 to 83+53) showed that the bedrock was competent to experiment with the stepped backslopes shown in appendix figure 19. When 

good fill or surface material is needed in a road and, for reasons of overall economy 

it can be obtained from a cut slope in a favorable location, then some treatment to 

dampen the appearance of the cut should be utilized. Shrubs were planted in this 

section to evaluate this treatment. 

6. Other selected 3/4:1 backslopes were planted to shrubs or grass. 

Revegetation success on road cut slopes steeper than 1:1 has not been good in most 

areas of the United States. The reasons are usually instability from air slacking or 

sloughing, and sometimes lack of moisture because of exposure (aspect). Grass seeding 

was carefully done with and without a mulch and shrubs were planted to test the cost 

and effectiveness on some selected slopes steeper than 1:1. 

7. Selected fill sections were straw mulched and rolled with an Angeles NFdesigned, sheep's foot-type roller to impregnate the straw and stabilize the surface of 

the fill slope. 

One of the most effective ways to stabilize steep, granular fill slopes is by 

impregnating straw with a special roller. The straw does not blow or wash off the slope, 

and the roller compacts the top 6 to 8 inches (15-20 em) of loose soil on the slope. 

4 
8. Neoprene downspouts were used because of better stability on the fill slopes 

and ability to dissipate part of the energy at the outflow. 

Although neoprene downspouts have been used quite often in the past few years, 

there is still a need for more testing, especially for functioning in different situations and for more information about the life of these structures. Because they do not 

require anchoring on the slope or connecting bands, they are not likely to be displaced. 

Design criteria produced a road shown in the following descriptions and table 1. 

--Length- 2.046 miles (3.292 km). 

--Width - 14 feet (4.27 m) with 3-foot (0.91 m) ditch--turnouts were combined with 

probable logging set locations; standard curve widening. 

--Maximum grade- 9.41 percent; average grade- 6.72 percent. 

--Minimum curve radius- 75 feet (22.9 m). 

--Surfacing - none. 

--Standard clearing width - 5 feet (1.52 m) from cut slopes and toe of fill. 

--Clearing from station 26+00 to 58+00 - trees cut selectively on both cut-and-fill 

sides--removed on cut side as near as possible without danger of slope failure; 

fill side a minimum of 8 feet (2.44 m) from road shoulder, or the branches trinmed 

to not interfere with traffic. 

--Culverts - 18-inch (0.457-m) C.M.P. minimum size. 

--Downspouts - flexible neoprene. 

--Compaction - with grading equipment. 

Table 1.--Grade, distance, and alinement--experimental section Abbot Basin Road 590-B 

Section Station Grade Distance No. curves Curve radius 

100ft % Mi (kmJ Degrees 

1 0-2+00 3.85 0.038 (. 061) 0 

2 2+00-5+00 6.60 . 057 . 092 2 108, 108 

3 5+00-7+00 4.65 .038 .061 0 

4 7+00-16+60 8.82 .182 .293 2 716, 573 

5 16+60-21+00 8.64 . 083 .134 2 143, 143 

6 21+00-25+00 6.84 .076 .122 0 

7 122+14-26+50 9.12 .083 .134 2 286, 358 

8 26+50-30+50 5.25 .076 .122 2 88, 88 

9 30+50-36+00 8.22 .104 .167 3 119, 358, 358 

10 36+00-42+55 7.53 .124 .200 4 409, 

11 42+55-48+00 3.85 .103 .166 2 75, 

12 48+00-56+00 7.06 .152 .245 3 358, 

13 56+00-59+40 9.41 .064 .103 1 143 

14 59+40-65+50 6.19 .112 .196 2 204, 

15 65+50-70+50 4.45 .095 .153 1 500 

16 70+50-74+50 7.62 .076 .122 2 477, 

II 17 74+50-85+00 5.63 .199 .320 3 477, 

18 85+00-91+00 8.39 .114 .183 3 358, 

19 91+50-94+65 6.58 .069 .111 1 204 

20 94+65-99+00 1. 38 . 082 .132 1 286 

1Equation: 

For analysis purposes (used later), the road was divided into two sections--major 

climbing and switchback 0+00-59+40 and 59+40-99+00. 

Section 

Section II 

Ave. grade 

7.26% 

5. 90% 

Ave. curve radius 

229 

297 

5 

No. curves/mile(/km) 

19.4 

17.4 

(12.1) 

(10.8) 

204, 179, 

75 

358, 239 

179 

140 

573, 179 

143, 143 

358 
ALTERNATIVE DESIGNS, 

CONSTRUCTION,AND COSTS 

Alternate Designs and Construction Cost 

To evaluate the probable effects of alternative designs, the study road P-Line 

location is retained and adjustments for different standards made from the P-Line. 

(The P-Line, or route location, is of prime importance no matter what width or other 

parameter adjustments are made to the final design. Often it is impossible for design 

changes and innovations to compensate for inadequate route selection.) Because of the 

relatively small central angles for most curves on the design road, except the switchbacks, and because of the minimum curve radius of 75 feet (22.9 m), the primary adjustments made for two simulated road standards (an SN-16 (4.88) and a DN-24 (7.32)} were 

in road and clearing widths. The designations for road standards in the Forest Service 

are being revised. In the old system, SN-16 (4.88) designates a single-lane, normal 

16-foot-wide (4.88 m) road. In the new nomenclature, the numbers following the letter 

designations represent design speed. For example, S-15 (24.1) designates a single-lane, 

road designed for a speed of 15 miles per hour (24.1 km/h). The latter designation is 

more descriptive of the trafficability, but doesn't give specific information about 

width. However, often because of curve widening, width added for settling and slough, 

and turnouts, width of a single-lane road varies so much that very few sections.end up 

design-template width, anyway. Both designations for standard will be shown, with the 

design speed designation in parentheses. 

For comparison, the side-by-side quantities and cost will be shown for each case 

or standard below: 

I. SN-14 (4.27) (S-15 (24.1)) - 3-foot (0.91-m) ditch (the experimental road). 

II. SN-14 (4.27) (S-15 (24.1)) - 3-foot (0.91-m) ditch without backslope or 

clearing modifications; that is, 3/4:1 backslopes throughout, standard 

clearing widths. 

III. SN-16 (4.88) (S-17 (27.4))l/ - 3-foot (0.91-m) ditch with the same 

backslope and clearing modifications as the experimental road. 

IV. DN-24 (7.32) (D-24 (38.6)) - 4-foot (1.22-m) ditch with the same backslope 

and clearing modifications as the experimental road. 

The design quantities were computed using the computer program of the Northern 

Region, Missoula, Montana. Table 2 shows the construction items and cost for each of 

the above standards. 

1/ Normally a road would not be designed for a speed of 17-mi/h (27.4-km/h)--in 

this case, the 16-foot-wide (4.88-m) road with turnouts provides a facility for 17-mi/h 

(27.4-km/h) traffic. 

6 
Table 2.--Construction items, unit cost, total cost, and cost per kilometer (mile) of 

alternative road standards (Dollars) 

Alternative road standard 

Unit 

Construction: of Unit II III IV 

item measure: cost Units Cost Units Cost Units Cost Units Cost 

Clearing and 

grubbing hectare 4,568.00 3.24 14,800 3.44 15' 725 3.50 16,002 4.28 

(chipping) (acre) (1,850.00) (8. 00) (8.50) (8.65) (10.58) 19,573 

Clearing and 

grubbing hectare 3,951.00 2.54 10,032 2.57 10,144 2.74 3.50 

(burning) (acre) (1,600.00) (6.27) (6.34) (6.77) 10,832 (8.63) 13' 803 

Unclassified 

excavation meters3 1.63 34' 773 56,854 36,664 59,946 37,948 

(Std. I' II, (yards 3) (1. 25) (45,483) (47,957) (49,636) 62,045 

and III) 

Std. IV 1.25 59,086 

(0.96) (77,284) 74,193 

(linear) 

Slope meters 0.11 744 854 744 854 744 744 

Rounding (feet) (0.35) (2,440) (2,440) (2,440) 854 (2,440) 854 

Overhaul 

m3 km 2.63 82.3 217 159.8 148.9 205.5 

(yd3 mi) (1. 25) (173.3) (336.4) 420 (313.4) 392 (432.6) 530 

Corrugated 

metal pipe-- (linear) 

4.57 m (18 meters 26.30 152 4,000 152 4,000 177 211 

in) dia. (feet) (8.00) (500) (500) (580) 4,640 (691) 5,528 

Total cost $ 86,757 91,089 94,765 114' 481 

Cost per km 

(mile) for 26,370 27,686 28,804 34,797 

3. 29 km $/km (42,403) (44,520) (46,317) (55,954) 

(2. 046 mi) 

It is readily apparent from table 2 that using 1/10:1 backslopes, where subsurface 

conditions were favorable, and reducing clearing widths, saved cost ($4,333) and reduced 

impact with no adverse effects on logging or hauling cost. 

7 
The cost of a conventional road can be estimated from table 2 by using standard 

clearing and grubbing cost ($1,600/acre ($3,951/ha)) for these quantities for road 

standard I I. The estimated cost for a conventional road then is $8-8,965 vs $86,756 

for the experimental road. 

User Cost 

The differences in construction cost show the additional capital investment required for higher standard roads. One must also compare effects of standards on user 

cost. For most forest roads, timber hauling cost is the major user cost. 

As normal planning procedure, these costs are used· to compare the potential 

benefits with the impacts they create to assist in determining road standards. A 

volume of traffic of 10 vehicles per hour is assumed for the computation of minutes 

per round trip mile (kilometer) in tables 3, 4, and 5. This was done to make the 

comparison for traffic volumes more typical of a system road in this area. The 

Logging Road Handbook, Byrne and others (1960) was used for the computation. 

Tables 3, 4, and 5 show that when a road is laid lightly on the land (contoured), 

the alinement will usually control the speed, when ruling grades are less than 6 to 7 

percent. This means that any significant improvement in speed (reducing vehicle user 

cost) must be gained by increasing width, as was done in this case. 

Under the assumptions used for table 6, 12,936 M bd. ft. (51,223 m3) of timber 

would be carried over the road annually. Although 10 VPH is relatively light traffic 

when a substantial part of the traffic is logging trucks, 50 percent in this case, 

a rather large volume of timber could be transported each year. As traffic increases, 

especially logging traffic, users tend to favor higher standards because of lower costs 

(Gardner 1971). 

Table 3.--Minutes per round trip mile (km) - SN-14 (4.27) (S-15 (24.1)) 

Road 1 section_/ 

Grade 

Loaded Empty 

Alinement 

Loaded Empty 

I 

II 

I 

II 

2.55 (1.58) 

2.20 (1.37) 

Time gov21 by empty4.13 (2.57) 

3.80 (2.36) 

2.25 (1.40) 

1.90 (1.18) 

Total time 

RTM (RTKm) 

8.13 (5.05) 

7.30 (4.54) 

4.00 (2.49) 

3.50 (2.18) 

3.90 (2.42) 

3.50 (2.18) 

Distance 

RT 

2.26 (1.40) 

11.49 (0. 93) 

Time/section 

18.37 (11.42) 

10.83 (6.73) 

1/ Road sections are used to facilitate the hauling analysis as shown in table 1. 

2/ Increase dependent on spacing of turnouts. 

Total time RTM = 18.37 + 10.83 = 29.20 min 

Total time RTKm = (11.42) + (6.73) (18.15) min 

Weighted average for both sections= 7.79 min/RTM (4.84 min/RTKm) (15.4mi/h (24.8 

km/h)) 

8 
Table 4.--Minutes per round trip mile (lon)--SN-16 (4.88) (S-17 (27.4}) 

Road 

section 

Grade 

Loaded Empty 

Alinement 

Loaded Empty 

I 

II 

I 

II 

2.55 (1.58) 

2.20 (1.37) 

Governing 

time 

3.71 (2.31) 

3.47 (2.16) 

2.25 (1.40) 

1. 90 (1.18) 

Total time 

RTM (RTKm) 

7.41 (4.61) 

6.87 (4.27) 

3.70 (2.30) 

3.40 (2.11) 

3.50 (2.18) 

3.20 (1.99) 

Distance 

RT 

2.26 (1.40) 

1.49 (0.93) 

Time/section 

16.75 (10.41) 

10.24 (6.36) 

NOTE: Total time RTM = 16.75 + 10.24 = 26.99 min 

Total time RTKm = (10.41) + (6.36 = (16.77) min 

Weighted average for both sections= 7.20 min/RTM (4.52 min/RTKm) (16.7 mi/h (26.9 

km/h)) 

Table 5.--Minutes per round trip mile (km) - DN-24 (7.32) (D-24 (38.6)) 

Road 

section 

Grade 

Loaded Empty 

Alinement 

Loaded Empty 

I 

II 

I 

II 

2.55 (1.58) 

2 0 20 (1. 37) 

Governing 

time 

2 0 60 (1. 62) 

2 0 30 (1. 43) 

2.25 (1.40) 

1.90 (1.18) 

Total time 

RTM (RTKm) 

5.20 (3.23) 

4.60 (2.86) 

2.60 (1.62) 

2 0 30 (1. 43) 

Distance 

RT 

2.26 (1.40) 

1. 49 (0. 93) 

2.60 (1.62) 

2.30 (1.43) 

Time/section 

11.75 (7 0 30) 

6.85 (4.26) 

Note: Total time RTM = 11.75 + 6.85 = 18.60 min 

Total time RTKm = (7.30) + (4.26) = (11.56) min 

Weighted average for both sections= 4.96 min/RTM (3.08 min/RTKm) (24.1 mi-/h 

(38.8 km/h)) 

For the cost comparisons in tables 6 and 7, the following assumptions were made: 

Table 6 

--10 vehicles per hour (VPH)--with half of the traffic logging trucks and half 

administrative and other traffic. 

--cost of operating logging trucks, including the drivers' wages--0.25/min. 

--cost of operating other vehicles--0.04/min. 

--8-hour hauling day, 140 days per year use. 

--20-year road life. 

--6 percent interest. 

--6.0 M bd. ft. (23.8 m3 ) loads for logging trucks. 

9 
Table 7 

--5 VPH--half logging, half other. 

--all other assumptions same as table 6, except 

--average load of logging and residue trucks used from Coram experimental logging 

study--3.84 M bd. ft. (15.2 m3). 

Table 6. --Cost summary comparison (10 VPH--1/2 logging trucks_, 1/2 other traffic) 

Road 

standard 

I 

III 

IV 

Annual 

amortized 

cliff. in cost 1 

0 

+ 1,842.99 

+11,790.22 

Annual cliff. 

hauling cost 

- Dollars 

- 6,209.28 

-30,529.96 

lcapital recovery--6%,20-year life. 

Annual cliff. 

other traffic 

862.40 

-4,743.20 

Net 

cliff. 

- 5,228.64 

-23,482.94 

Table 7.--Cost summary comparison (5 VPH--1/2 logging trucks_, 1/2 other traffic) 

Road 

standard 

I 

III 

IV 

Annual 

amortized 

cliff. in cost 

0 

+ 1,842.99 

+11,790.22 

Annual cliff. 

hauling cost 

Dollars 

- 3,187.65 

-15,287.59 

Annual cliff. 

other traffic 

431.20 

-2,371.60 

Net 

cliff. 

-1,775.86 

-5,868.97 

The data in table 7 more nearly approximate the traffic volume for the experimental 

sale (presently a dead end road), although the traffic was more intermittent and did 

not extend for a full 140 days during the year of the logging (1973). 

Table 7 also indicates that this volume of traffic is near the break even point 

for road standards (primarily width in this case) related to hauling cost. For this 

particular road, just wide enough for the logging equipment, any environmental values 

obtained would cause little economic sacrifice. (For the Coram experimental sale, only 

about 1 1/2 million board feet (5,535 m3) were harvested). 

The preceding discussion and comparisons would be useful for deciding road standards. To complete an analysis of road standards, the effect of the road standard on 

harvesting cost as well as hauling cost would be necessary. However, the effects on 

harvesting cost could not be made for this study where only one standard was built. 

10 
ROAD PERFORMANCE TO DATE 

Structural Features 

Road inspections of April and June of 1974 and observations throughout the summer 

and fall of 1974 showed no structural failures of any kind. Some minor sloughing and 

settling had occurred. 

1/10:1 backslopes.--Two photos taken from approximately station 54+00, after the 

first winter and after final grading, tell the story. Figure 2 shows two or three sections where 1/2 to 1 cubic yard (0.13-0.26 m3 ) of rock sloughed off the cut bank. Figure 3 shows the same section of road after final grading and how it appeared the balance 

of the year. Only minor sloughing is likely in the future. 

3/4:1 backslopes.--Two areas of 3/4:1 backslopes showed some sloughing or slumping 

after the first winter, but are now relatively stable and no major failures are anticipated. Figure 4 shows minor slumping at station 37+20 on a relatively long slope in 

the deepest soil mantle found on the entire road. Some minor sloughing or slumping 

could be expected on 3/4:1 backslopes in this material. 

Figure 2.--Near station 54+00--view of 1/10:1 backslopes before final grading. 

11 
Figure 3.--Near station 54+00--view 1/10:1 baekslopes after final grading. 

Figure 4.--Slumping cut slope near station 37+20. 

12 
Figure 5.--Minor settlement in rock fracture at station 64+34. 

A minor U-shaped settlement occurred in the cut bank at station 64+34 (fig. 5) 

because of rock fracturing. 

In figure 6, several yards of rock slabbed off the cut bank at station 76+20 

because of dip and fracture in the bedrock. No further sloughing of any extent is 

expected here. 

Stepped or serrated backslopes.--An experimental section of approximately 450 feet 

(137 m) of backslope was stepped to test growth of grass and shrubs and to evaluate 

esthetics and stability. This area has relatively high precipitation and a favorable 

aspect. Revegetation success was generally good. Figure 7 shows a completed section 

of serrated backslope. The dip and strike of the rock formations made stepping difficult and resulted in the steps being not quite as wide as planned. The steps have been 

planted, and it is believed that most of the sloughing expected has taken place. Sloughing eventually leaves less pronounced steps, but provides a seedbed and more moisture 

to the plants. 

Fill slopes.--Fills were designed on either a 1 1/2:1 or 1 1/4:1 slope, depending 

on the material. Many sections contained enough rock to support 1 1/4:1 slopes. Fill 

slopes were compacted by the earth moving equipment. Figure 8 shows a typical fill at 

station 87+75. The material in the area of station 93+00 produced the only section 

where the fill slope was slightly undulating, shown in figure 9. 

13 
Figure 6.--Rock slab spalling due to dip and fracture at station 76+20. 

Figure ?.--Stepped backslopes in rock cut near station 82+50. 

14 
Figure B.--Typical side-cast fill on 1 1/2:1 slope at station 8?+?5. 

Figure 9.--Fill containing some fine colloidal material that produced a slightly 

uneven but stable slope at station 93+00. 

15 
Drainage 

Drainage is provided by a 3-foot (0.91-m) ditch, corrugated metal pipe, and neoprene downspouts. Only three culverts experienced any flow during the first year. 

However, seasoning of the ditch sections will produce more flow in the future. 

Minor seepage was recorded in April from four cut bank sections at stations 12+40, 

21+75, 41+00, and 55+00. The seepage at the first two locations continued throughout 

the year, but no damage resulted from the seepage. A typical area of seepage is 

station 41+00, shown in figure 10. 

, Neoprene downspouts were used because of their greater stability on fill slopes 

and effectiveness in dissipating part of the energy under conditions of flow. The 

installation at station 57+50 is shown in figure 11. 

Porous soil over the fractured limestone basin minimized the need for water 

control. 

Figure 10.--Typical minor seepage at station' 41+00. 

16 
Figure 11.--Neoprene downspout laid on top of fill 

at station 57+50. 

Slash from the road 

chipping and scattering. 

much more small material 

in very small volumes of 

a concentration of chips 

cases, were chipped in a 

Clearing 

right-of-way was disposed of on the first 59 stations by 

Because of this requirement, the contractor removed and sold 

than he would have on a pile-and-burn operation. This resulted 

material being chipped and scattered. The author couldn't find 

visible enough to photograph! Only the tops and limbs, in most 

small Fitchburg right-of-way chipper. 

The difference in overall appearance between the standard and reduced clearing 

widths can be seen in figures 12 and 13. As previously discussed, reduced clearing 

widths generally reduce esthetic impacts. 

17 
Figure 12.--Road section~ conventional clearing. 

Figure 13.--Road section with vertical cut and reduced clearing width. 

18 
Erosion 

Runoff and erosion were not anticipated to cause significant problems because 

of the leaky, fractured limestone basin and the road material. There was no evidence 

of overland flow on the location before the road was constructed, and very little subsurface flow has been intercepted by the road prism. Obviously, the percolation rate 

is high and the phreatic gradient steep. 

The first year after construction, ditch flow was small and carried little or no 

sediment. No evidence of overland flow of sediment was found and little or no sediment 

is expected. The entire section of road is separated from any live stream. Hence, 

if in the future any sediment flow does develop, it would not reach a live stream. 

Revegetation 

Because the revegetation experiments will be reported in detail in another paper, 

only the generalities will be discussed here. The primary objectives of revegetation 

were to help stabilize the slopes and reduce visual impact. The relative importance 

of these objectives for any road varies with the location of the road. Location affects 

stability and visual considerations. For example, in some cases, revegetation could be 

entirely for esthetic reasons. 

The shrubs and grass used for revegetation were listed in appendix tables 8 and 9, 

along with the first-year survival on the shrubs. Obviously, the effect of these plantings on the appearance of the road cannot be evaluated until the shrubs have had some 

time to develop. Initial survival is very good and, since this is the most critical 

time for survival, good overall results are expected. 

Fill slopes that are difficult to revegetate have generally been most successfully 

treated by applying a mulch held in place by netting or impregnation. The sheep's 

foot-type roller, designed by the Angeles National Forest (fig. 14), has been proven 

effective in compacting the top 6 to 8 inches (15-20 em) of soil, while at the same 

time impregnating straw mulch well into the soil. The roller was used on several fill 

sections; results will be reported when data have been analyzed. (The experimental 

seeding and planting were done by research personnel and were not a part of the road 

contract.) 

Figurae 14.--Angeles N.F. roller-compactor. 

19 
Esthetics 

As emphasized in this report, esthetics are probably influenced by the width of the 

road cross-section and clearing more than anything else. (Also, visual impact of the 

effects of raw cut-and-fill slopes, whatever the road width, is reduced by revegetation.) 

A view of the basin (showing the old road) before clearing for the new road is 

shown in figure 15; a view after clearing for the new road is shown in figure 16. 

(Figures 12 and 13 show two sections of the new road, particularly effects of reduced 

clearing width.) 

In figure 15, the clearing and cross section of the old road are prominent in the 

center of the picture. In figure 16, the same view after the new road was completed, 

the clearing for the new road is barely visible above the old road. Figure 12 shows a 

cut-and-fill section using conventional backslopes and clearing specifications. Compare 

this photo with figure 13 where 1/10:1 backslopes and reduced clearing widths were used. 

(Both photos were taken before final cleanup and grading.) 

To minimize miles of road, one must use logging systems that require few roads. 

The research on the Coram site was to demonstrate the effects of logging systems that 

require fewer miles of road and produce less impact than conventional methods. Instead 

of the traditional Idaho jammer that required road spacings of 300-600 feet, (91-182 m) 

a skyline system was selected that had the potential to increase road spacing to about 

2,000 feet (610 m). In steep country (>SO percent slopes), if road spacings are decreased, it generally means the road will require switchbacks to gain elevation. This 

was the case for the experimental portion of Abbot Basin road 590-B, as seen in figure 

2 and appendix figures 18 and 19. 

Figure 15.--Abbot Basin before construction of logging study road. 

20 
Figure 16.--Abbot Basin after construction of Zagging study road. 

DISCUSSION AND CONCLUSIONS 

In the future, an important consideration for construction of forest roads will be 

to reduce the environmental and social impact while still providing access needed for 

resource utilization. 

For the experimental road on the Coram research site, a decision was made to reduce elements of design to the near minimum needed for operation of the logging equipment and evaluate the results. The road is located on an experimental forest and is a 

system road, but subject to atypical volumes of traffic because it is dedicated to 

research experimentation. Therefore, the road was evaluated for both the traffic 

associated with experimental logging and traffic assumed for a typical system road. 

For the experimental sale, the single-lane road clearly was the best choice, 

environmentally. For a system road carrying normal traffic, including timber volumes 

of up to 4- to 5-million bd. ft. (15,840-19,800 m3 ) annually, the reduced environmental 

impacts of a well-designed and well-constructed single-lane road may still be available 

at some acceptable level of economic sacrifice. For heavier volumes of traffic, especially logging traffic, then the trade-offs become more significant and require more 

difficult decisions about standards. 

Estimated hauling cost differences for a wider single-lane road and a double-lane 

road for two assumed traffic volumes (10 VPH and 5 VPH) showed the 5 VPH traffic near 

the break even point for single-lane vs double-lane roads related to hauling cost for 

this sale. 

21 
Although final reports are not yet available from the results of esthetic and 

hydrologic impacts and revegetation experiments, some general observations are possible. 

Esthetic impacts of a single-lane road with reduced clearing widths definitely appear to 

have been an improvement over standard practices. 

Although the hydrology has been changed, as it always is when logging and road 

construction are imposed on the land, there is no evidence to date of adverse impacts 

from sediment or changes in runoff and streamflow. 

Early results from the revegetation experiments show good success from the shrub 

planting and the impregnated mulch treatment. The plantings and seeding experiments 

will be effective in reducing visual and environmental impacts. 

PUBLICATIONS CITED 

Byrne, James J., Roger J. Nelson, and Paul H. Googins. 

1960. Logging road handbook: the effect of road design on hauling costs. U.S. Dep. 

Agric. Handb. 183, 65 p. Washington, D.C. 

Gardner, R. B. 

1971. Forest road standards as related to economics and the environment. 

USDA For. Serv. Res. Note INT-145, 44 p. Intermt. For. and Range Exp. Stn., 

Ogden, Utah. 

22 
APPENDIX A 

Alinement Experimental Section Abbot Basin Road 590-B 

23 
24 
PI 93+38.30 

/, 

Pig I 

~~/ 

25 
Variable as shown on the Ions 

10'(J.05m) 

------'--=---------1-=-7 '(2.13m)C enter line 

Construct 

to dimensions as shown 

7' 

TYPICAL TURNOUT SECTION 

No Scale 

(STO) On split turnouts are similar to above with 5ft extra 

\ width being added to each side of roadway 

(0.9~m( 

~31----7' 

~~··' 1' (0.30m) 

--,--

Center 

line 

TYPICAL SECTION 

No Scale 

Center 

STEPPED BACKSLOPE 

Sta 79 + 09 to Sta 83 +53 

No Scale 

Figure 19.--Typical sections for turnouts~ cut-and-fill slopes~ and stepped backslopes. 

26 
APPENDIX B 

Revegetation of Road Slopes ... Shrubs and Grasses Planted 

Table 8 . --Shrub survival data--spring planting 19?4 to fall 19?4 

Site Site 2 Site 3 Site Site Site 6 Total 

Species No. No. No. No. No. No. : No. 

planted planted : % planted : % planted planted : % planted : % :planted 

Woods rose 249 98 96 92 89 99 80 94 41 95 86 94 641 96 

(Rosa woodsii) 

Redosier dogwood 33 100 14 94 46 100 93 99 

(Cornus stolonifera) 

Chokecherry 316 87 62 92 134 72 91 86 59 95 106 85 768 85 

(Prunus virginiana) 

Serviceberry 404 84 75 76 129 87 103 93 66 82 151 89 928 85 

( Amelanohier florida) 

Blackcap 39 85 23 87 62 85 

(RubuP. occidentalis) 

Spirea 188 72 66 66 138 41 73 92 461 65 (Spirea luoida) 

Blue elderberry 27 96 27 96 

(Sambucus g lauoa) 

Black elderberry 49 59 23 30 72 so (Sambucus canadensis) 

Redstem ceanothus 303 66 56 41 106 13 95 67 63 27 113 73 736 54 

(Ceanothus sanguineus) 

Ninebark 68 75 25 72 93 74 

(Physocarpus malvaceus) 

Beard tongue 170 65 48 46 97 26 66 64 88 51 469 52 

(Penstemon uk.) 

Thimbleberry 35 80 24 79 59 80 

(Rubus odoratus) 

Sumac 27 44 19 47 46 46 

(Rhus glabra) 

Mountain mahogany 29 45 29 45 

( Cercocarpus) 

Evergreen ceanothus 322 21 93 28 120 16 89 28 57 33 81 33 762 24 

(Ceanothus uk.) 

Ocean spray 26 24 13 so ( Ho lodiscus discolor) 

Lupine 236 lOS 3 84 52 95 572 

(Lupinus) 

27 
Table 9.--Grass and legume mixture used to seed slopes of 

experimental road. 

Species Rate/acre Kg/hectare 

Pounds 

Alta tall fescue 

Manchar smooth brome 

Orchard grass 

2.5 

4.0 

2.5 

2.0 

2.0 

(Kg) 

(2.81) 

(4.49) 

(2.79) 

(2.25) 

(2.25) 

White Dutch clover 

Birdsfoot trefoil 

Headquarters for the Intermountain Forest and 

Range Experiment Station are in Ogden, Utah. 

Field programs and research work units are 

maintained in: 

Billings, Montana 

Boise, Idaho 

Bozeman, Montana (in cooperation with 

Montana State University) 

Logan, Utah (in cooperation with Utah State 

University) 

Missoula, Montana (in cooperation with 

University of Montana) 

Moscow, Idaho (in cooperation with the 

University of Idaho) 

Provo, Utah (in cooperation with Brigham 

Young University) 

Reno, Nevada (in cooperation with the 

University of Nevada) 

~U.S. GOVERNMENT PRINTING OFFICE: 1978-0-777- 095-76 

28 
Gardner, Rulon B. 

1978. Cost, performance, and esthetic impacts of an experimental 

forest road in Montana. USDA For. Serv. Res. Pap. INT-203, 

28 p. Intermt. For. and Range Exp. Stn., Ogden, Utah 84401. 

An experimental logging road designed to minimize environmental and 

esthetic impact was constructed in northwest Montana. The road was 

single-lane (14-foot finished surface, 3-foot ditch), constructed along the 

contour. Esthetically, the single-lane experimental road was judged far 

superior to existing roads on the forest. 

KEYWORDS: forest roads, logging roads, road design, environmental impact 

Gardner, Rulon B. 

1978. Cost, performance, and esthetic impacts of an experimental 

forest road in Montana. USDA For. Serv. Res. Pap. INT-203, 

28 p. Intermt. For. and Range Exp. Stn., Ogden, Utah 84401. 

An experimental logging road designed to minimize environmental and 

esthetic impact was constructed in northwest Montana. The road was 

single-lane (14-foot finished surface, 3-foot ditch), constructed along the 

contour. Esthetically, the single-lane experimental road was judged far 

superior to existing roads on the forest. 

KEYWORDS: forest roads, logging roads, road design, environmental impact 
FOREST RESIDUES UTILIZATION 

RESEARCH AND DEVELOPMENT PROGRAM