extended to those not listed. Effectiveness of any
availability of material. It is possible that aggre-
technique is a function of many variables. What is
gate sources are simply unavailable. Because thaw-
the life expectancy of the road? (Is the purpose of
ing is the source of the immobility problems ad-
the road rapid deployment indicating a tempo-
dressed here, borrow sources may still be frozen,
rary road, or will it serve as the base of a future
inaccessible, or of poor quality, and susceptible to
road as in rebuilding an infrastructure in a war-
thaw weakening.
torn environment?) How about exposure to en-
emy fire? Tree slash may be readily available, but
Chunkwood
placement is extremely labor intensive and re-
Chunkwood proved to be an excellent substi-
quires extensive periods of exposure by person-
tute for gravel for the Fort McCoy demonstration
nel. Equipment availability may eliminate a par-
project. Not only was it successfully used in test
ticular technique or process. The site may be in a
sections as planned, but it also served as the main-
forested area, but without a wood chunker or
stay stabilization technique for the entire project.
wood chipper, chunkwood or wood chips are
When access roads to test sites became impass-
clearly eliminated. Likewise, if foot traffic or pas-
able, chunkwood was used to reconstruct and
sage with small rubber tired vehicles is antici-
allow passage. Because of its low density, it can be
pated, tire chips including steel bead should not
supported by very weak subgrades that might
be used as a wear surface. The steel pieces in tire
not be capable of supporting necessary aggregate.
chips have been shown to puncture both rubber
A gravel wear surface can be added for use as a
tires and boots.
permanent road. As a base course beneath gravel
We are not restricting recommendations to only
cover, the chunkwood provides an excellent insu-
those techniques listed. Only mechanical stabiliz-
lating layer to reduce detrimental effects of frost
ing techniques were demonstrated. Neither chemi-
action in areas of seasonal freezing. However,
cal nor chemical-mechanical techniques were con-
chunkwood's success relies on the availability of
sidered. Additionally, only a limited number of
a source of trees and the development of a com-
surfaces representative of each stabilization prin-
mercial chunker. It is possible that more conven-
ciple were discussed. For example, portable wood
tional wood chips may serve in a similar capacity
pallets and prefabricated large wood mats were
to chunkwood; additional testing is recommended.
considered representative of rigid mats. However,
there also exist a variety of rigid mats made of
Tire chips
fiberglass and "high-tech" plastics. Many of these
As was the case of conventional roads and
mats are lightweight and high strength. While
chunkwood, construction requires no special
material costs are generally higher than wood
equipment or training. Tire chips can be supported
products, the ground area covered by one truck-
by weak subgrades not capable of supporting a
load/planeload of fiberglass mats is appreciably
gravel embankment. As with chunkwood, a gravel
larger than the area covered by heavier, more
wear surface can be added, and the tire chips
bulky wood mats. Tradeoffs must be considered
provide an excellent insulating layer. Another ad-
in selection. If it is known that delivery will be
vantage of tire chips is utilization of a waste prod-
limited, the more expensive, lighter weight mats
uct. However, it is imperative that no steel bead
would be recommended.
or foreign steel pieces be contained in the tire
chips, if the road is to be used as a trafficking
surface for small rubber-tired vehicles (or foot
SUMMARY AND
travel). Additionally, environmental concerns
CONCLUSIONS
(some states prohibit tire chip base courses when
The following discussion briefly summarizes
placed below the seasonal high water table) and
Tables E1 and 6, taking into account construction,
flammability need to be addressed.
test section performance, and vehicle/mobility
aspects of the demonstration project.
Tree slash
Tree slash is inexpensive and placement re-
quires no special equipment or training. Its avail-
Conventional road
A conventional gravel road is unquestionably
ability is slightly broader than that of chunkwood
one of the simplest of the techniques demon-
simply because scrub brush, old corn husks, or
strated. Dump trucks, loaders, and bulldozers are
any bulk vegetative material may be used. A ma-
standard equipment. The problem, of course, is
jor drawback is that placement is labor intensive
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