Off-roading is a term for driving a vehicle on unsurfaced roads or tracks, made of materials such as sand, gravel, riverbeds, mud, snow, rocks, and other natural terrain.
- 1 Off-road vehicle
- 2 Different uses of the term throughout the world
- 3 Recreational off-roading
- 4 Off-roading events
- 5 Off-roading organizations
- 6 Vehicle modification
- 7 Criticism of ORV use
- 8 See also
- 9 References
- 10 External links
In most cases off-road terrains can only be traveled by vehicles designed specifically for off-road driving such as ATVs, heavy-duty pickup trucks, trucks and equipment, sport utility vehicles (SUVs), snowmobiles, motorcycles or mountain bicycles. These types of vehicles often have extra ground clearance, sturdy tires, and front and rear locking differentials. Examples of vehicle manufacturers notable for producing types of off-road vehicle (ORV) include AM General, Land Rover,and Jeep, though many vehicle manufacturers have some sort of off-road vehicle in their current range. Trucks are often fitted with these extras by default. Military forces usually design their vehicles with off-roading in mind or buy them from off-road manufacturers such as AM General (Humvee), Jeep, and Land Rover, who have produced vehicles used by the armed forces of many countries.
Different uses of the term throughout the world
In some parts of the world, off-roading is the normal form of transportation. In tropical countries unsurfaced roads can attain off-road aspects during the rainy season when extra gear ratios and four wheel drive can become necessary. In Western countries the term "off-roading" is frequently used more for recreational pursuits.
Recreational off-roading is popular among a sub-section of the owners of four wheel drive or all-terrain vehicles and motorcycles. There are numerous categories of recreational off-roading, with something suitable for all levels of experience and equipment.
Some of the major categories of recreational off-roading are listed below:
Dune bashing involves driving over sand dunes, frequently associated with tourism in the Middle-East. There are also many state parks in the United States that allow ORVs to drive on them including the Silver Lake Sand Dunes in Michigan and the Imperial Sand Dunes in California. A specialized type of Dune-bashing is Tatees which uses highly modified vehicles with modified engines and sand-tires to climb a single slipface of a Star dune or so which usually are a hundred meters high or more. Tatees (Arabic: تطعيس) is derived from Taas (Arabic: طعس) which is usually a Star dune commonly found in the Empty Quarters (Arabic: ربع خالى) in the south of Arabian peninsula.
By far the most common recreational offroading in North African Sahara desert. Because of vast uninhabited expanses of desert, this remains to the moment a legal activity unlike possible similar 4x4 trips in Europe. And unlike localized Dune bashing that tends to revolve around a single Star dune or one obstacle, Cross-country is a several days desert safari that navigates through largely unchartered terrain. Such expedition-like safaris tend to use skills rather than highly modified vehicles to cross one obstacle after another over large distances that usually exceeds 200km of pure offroading.
Greenlaning (or two-tracking) is one of the least extreme categories. It is generally suitable for any four wheel drive vehicle, even with factory tires and equipment. The term greenlane refers to the fact that the routes are predominantly along unsurfaced tracks, forest tracks, or older roadways that may have fallen into disuse. For a lot of greenlaners the main emphasis is on enjoying the countryside and accessing areas that may be seldom traveled by motor vehicles, rather than exploring the performance envelope of their vehicle.
Greenlaning is popular among All Wheel Drive (AWD) SUVs with limited off-road capabilities, being designed for only light off-roading in normal use.
Mudding (or mud bogging)
Mudding involves finding a large area of wet mud or clay and attempting to drive as far through it as possible without becoming stuck. The stock tires supplied with four by four vehicles are typically inadequate for this type of off-roading and Mud-terrain tires are required. Strongly attached recovery points are also recommended to enable the vehicle to be towed out if it becomes bogged down. Traction and momentum are important factors in success.
Rock crawling is a highly technical category of off-roading. Vehicles are typically modified with larger than stock tires, suspension components that allow greater axle articulation, and changes in the differential gear ratio in order to provide the ideal high torque/low speed operation for traversing obstacles. It is common for a rock crawler to have a "spotter – an assistant who will go on foot alongside of or in front of the vehicle to provide information to the driver on obstacles or areas of terrain that the driver may be unable to see.
Rock Racing is very similar to rock crawling in the fact that the vehicles are driven over rocks, the difference is that there are no penalties for hitting cones, backing up or winching as is done in rock crawling. Rock racing also involves a degree of high-speed racing not seen in typical rock crawling.
Trials are probably the safest form of motorsport. All progress is made at low speed and the emphasis is on skill, rather than finishing first although trialing can be highly competitive. There are three traditional forms of off-road trialing.
RTV (Road Taxed Vehicle) trialing is the most common form of trialing. As the name suggests, it is for vehicles that are road-legal (and thus required to pay vehicle excise duty). This excludes vehicles that are highly modified or specially built. RTV-class vehicles can carry a wide range of suspension modifications, as well as off-road tires (provided they are road-legal), recovery winches, raised air intakes etc. Vehicles on RTV trials are usually best described as "modified from standard"—they use the standard chassis, drive-train and body that the vehicle was built with. Whilst modification is not necessarily required for an RTV trial, at the very least the vehicle would be expected to have some under-body protection such as a sump guard, differential guard and solid sills. RTV courses are intended to be non-damaging and driven at little more than a walking pace and a course properly laid out would be drivable without damage. However, the terrain usually includes steep slopes, water, side-slopes, deep ruts and other obstacles that could potentially damage a vehicle if mistakes are made or poor driving technique is used, and vehicle modifications increase the chance of success.
RTV trials usually take place on farmland, a quarry site or at a dedicated off-road driving center, and are usually organized by a dedicated trialing body (such as the All Wheel Drive Club or The Association of Land Rover clubs in the UK), or by a vehicle owner's club. The course consists of 10 to 12 "gates" marked by two garden canes, vertically placed. The gates are just wide enough to get a standard vehicle through. One vehicle attempts the course at a time, and is deemed to have cleared a gate if at least one of the front wheel hub passes between the canes. The vehicle's attempt ends when it comes to a stop (depending on the exact level of skill the trial is aimed at, any stopping may end the attempt, or a few seconds may be allowed). Long-wheelbase vehicles are usually allowed to perform a three-point turn if needed, providing the driver declares where the turn is going to be made before they attempt the course (this puts a strong emphasis on ground-reading ability). This can also be called a "shunt" where the driver has to attempt a gate and then shout shunt. they are then allowed a space of 1 and a half car lengths to reverse and line the car better to enter through the gate
The course between the gates is a "section": between the start line and the first gate is "Section 1", the part between the first and second gates is "Section 2" and so on. An RTV course is often laid out so that each section is progressively more difficult, although this is not always the case. If a driver fails to complete Section 1 they are given 10 points. If the attempt ends in Section 2, 9 points are awarded etc. A clear round results in gaining only 1 point. A day's event will consist of many different courses and the driver with the lowest score is the winner.
Since the terrain covered in RTV trials should be well within the capabilities of any reasonably capable vehicle (even in standard form), these trials place the emphasis on driver skill and ground-reading abilities. A good driver in a standard specification vehicle can easily win over a modified, highly equipped vehicle driven by a less competent driver.
Cross Country Vehicle (CCV) trialing is the next step up from RTV trialing and is open to non-road-legal vehicles, which greatly increases the scope for modification. The terrain covered will be of greater difficulty than that found on an RTV trial, and will usually require more judicious use of speed to get the vehicle across certain obstacles, so increasing the risk of vehicle damage. Whilst no trial is intended to be vehicle-damaging mistakes and accidents are inevitable. A standard-specification vehicle would not be expected to be able to complete a CCV course.
The event is run along the same lines as RTV, with a course made up of cane-marked gates. The rules are also the same as an RTV trial.
CCV trialing differs greatly from RTV trials in the vehicles used. Since "anything goes", CCV trials rely on having the correct vehicle to a much greater extent than in an RTV trial. Competitors are able to design and build vehicles that are much more optimized for off-road use than in the lower ranks of trialing. CCV vehicles have powerful engines, high ground clearance, light, minimalist bodywork and good approach and departure angles. For many years, in the UK, the ultimate CCV vehicle could be built by taking the chassis of a Range Rover, removing the body, cutting the chassis down to an 80-inch wheelbase and mating it to the body of a Series I Land Rover, retaining the Range Rover's V8 engine and coil-spring suspension in a light, easy to maneuvre body. In recent years the value of early Land Rovers and Range Rovers has risen to the extent that this is no longer practical. CCV triallers now usually base their vehicles around Land Rover 90s or a standard 100-inch chassis from a Range Rover or Series I Discovery. The Suzuki SJ series of vehicles also make good bases for CCV-spec vehicles. Some vehicles are specially built, taking the form of light "buggies" with tractor tyres and "fiddle" brakes for the best performance.
Vehicles are required to meet certain safety regulations. Roll-cages must be fitted and be built to a suitable standard, recovery points must be fitted front and rear and fuel tanks must meet certain standards. A 4-point harness for all occupants is required and a fire extinguisher is recommended.
Punch & winch challenge
This is the most recent, and usually the most difficult, form of course trialing. A course is laid out with either a series of punches or gates and vehicles must collect as many punches[clarification needed] as possible or complete as many gates in a course as possible. These challenges often include a small number of special stages.
The events take place on very difficult terrain and vehicles are not expected to be able to complete the course without the use of a recovery winch. Winching is a definite skill in itself, aside from off-road driving, and brings elements of team-play into the trial, as a successful (and safe) vehicle recovery needs at least 2 people to complete. Some trials are for teams of 2 or 3 vehicles, each helping to recover the others through obstacles. A Winch Challenge may extend to other off-road driving skills, such as building a log bridge to cross a river.
At its most basic a winch challenge vehicle will be a CCV-spec machine with a front-mounted recovery winch. However, a distinct breed of vehicles adapted for Winch Challenges has evolved. The small, open-topped CCV vehicles are not well suited to carrying the often large range of equipment needed for winch recovery in difficult terrain. A larger vehicle with some form of protection from the elements is desired (the short-wheelbase Land Rover Defender, especially in "Hard Top" guise, is a typical and common basis for a Winch Challenge vehicle).
Vehicles often require extensive modification. Under-body protection is needed, given the severity of the terrain involved, enhanced suspension travel and reinforced drive train upgrades are used to get vehicles as far as possible before winching is needed. Roll-cages and "snorkel" air intakes are required to prevent vehicle damage. The vehicle's electrical system often needs upgrading with multiple battery banks and high-output alternators needed to cope with the large currents drawn by a winch. Hydraulic Winches are replacing electric winches in the most competitive vehicles. Vehicles increasingly sport winches mounted at the front and rear and often in the centre to right a vehicle that has toppled over to greatly increase the options available for recovery. The extreme demands on the vehicles have led to the evolution of hybrid trayback[clarification needed] vehicles.
There are other forms of trialing, usually based around one of the above types but with a slight difference. These are often used as more "fun" events within a vehicle club, rather than as a part of a formal championship. Examples include:
- Punch-Card Challenge. Usually based around an RTV trials course. Instead of a series of gates around a fixed course, a number of single canes are placed around a site. Each cane is numbered and a hole-punch tied to the cane. Each vehicle has a card with numbered squares marked on it. The card is tied to the exterior of the vehicle (usually from the wing mirror). The aim is to get the vehicle close enough to the cane so that the hole punch can be used to mark the appropriate square on the card. The punches usually use a pattern of pins to prevent one punch being used to cheat by punching a number of squares on the card. Unlike a trial course, the vehicle does not have to pass through a gate, it simply has to approach a cane and leave the cane. This tests driver skill and ground-reading, as the most obvious way to approach a cane is often not the easiest. For example, with a cane situated at the bottom of a steep slope it may turn out that the flat terrain at the base of the slope is too soft or muddy to drive over. The only way to the cane is to drive across the slope, stop (whilst the vehicle is tilted), punch the card and then continue. The winner is the driver who has collected the most punches.
- Tyro trial. The name derives from the Latin word "tyro" meaning "new recruit". "Tyro" trialing is intended as an introduction to the sport for newcomers or children and is the most basic level of trialing. These take the form of a course with gates, but the course is carefully laid out so that it requires definite skill to drive, but carries no risk of damage to the vehicle or injury to the driver. Vehicle modifications are not allowed. Some tyro trial organizers even ban the fitting of different types to tyres to those the vehicle left the showroom with.
Winch events often involve attempting to access areas that would be impassable without the use of a winch – this can include traversing deep gullies, steep slopes and so on. Most off-road vehicles that have been prepared for this type of event will typically have two winches, one at the front and one at the rear of the vehicle, each with a rated pull of over 9,000 lb (4,100 kg).
In some countries off-road activities are strictly regulated, while others promote cross country off-road endurance events like the Dakar Rally, Baja 500 & 1000, Spanish Baja and the Russian Baja Northern Forest which are a test of navigation skills and machine durability. off road parks and motocross tracks also host a number of events and may be the only legal place to off-road in the area. Events include jamborees, rock crawling competitions, Mud Bog races, Top Truck Challenges and sand racing as well as many other events, such as the Tank Trap.
Russia has very busy off-roading championship 5-7 starts every year. Also every club has it is own events, in Tambov off-road club Сhernozem has 4 traditional races and the most popular off-road race in Russia is Ladoga-race in Karelia.
Organizations and associations have been formed and many show a united front in the battle to keep public lands open to off-roaders. Some organizations, such as the Blue Ribbon Coalition and Tread Lightly!, are not off-road clubs at all and are solely set up to fight land closures and to promote environmentally friendly off-roading.
While many off-road vehicles can Greenlane or "two track" most un-surfaced roads, the desire of many off-roading enthusiasts is to attempt much more challenging terrain. The following listings show the modifications that are done and why:
A vehicle lift is when the normal height of a vehicle is lifted to increase the amount of clearance between the ground and the bottom of the body or frame of the vehicle. There are numerous types of vehicle lifts:
A simple and cheap way to lift a vehicle that has a body on frame design such as a pickup truck or some SUVs. A body lift consists of larger spacers that replace the normal mounting points of the vehicle's body on its frame. These typically are between 1–4 inches. Any more than four inches (102 mm) will create a less sturdy set up. Body lifts are not possible on vehicles with a "Uni-body" construction. Uni-body vehicles have the frame formed into the body, such as on a late model Jeep Grand Cherokee. Body lifts permit the fitting of oversized tires, but do not otherwise contribute to ground clearance.
A suspension lift is when modifications are made to the vehicle's springs, shock absorbers, controlling arms and steering linkage. In this case small or short pieces of the suspension are replaced with longer or larger items of similar construction. Lifting a vehicle changes its driving dynamics and a suspension lift adds to the vehicle's handling capabilities in relation to the increased height (see lifting concerns below). Some examples of this are:
- Larger arced Leaf springs
- Longer Coil springs
- Coil spacer blocks
- Leaf spring spacer blocks
- Longer Control arms
- Longer Pitman arms
- Air bag spring replacement
- Longer leaf spring shackles
- Reverse leaf spring mounting on the axle
- Longer Spindles in the front
Unlike a suspension lift, which only lifts the vehicle's body, an axle lift can either be achieved by fitting larger tyres or mounting portal axles. The downside of fitting larger tyres is the increased stress on the axle hubs, half shafts and the driveline. This always requires modifications to the latter, e.g. reinforcing drive shafts, differentials, etc. The more suitable option is a portal axle. By adding a gearing to the end of the axle the centre of the wheel is lowered. There are currently a few different approaches to achieve this. Most often in the past portal axles from existing vehicles, e.g. Volvo C303, Unimog or other, have been modified to fit under the offroad vehicle of choice, e.g. Land Rover Defender, Jeep Wrangler.
An alternative is bolt-on portals which are fitted to the original axle flange. The advantages of this option are the limited work necessary, compared to modifying an axle to fit another vehicle.
A quick and easy way to gain ground clearance is to increase the size of the tires on a vehicle. One advantage over body and suspension lifts is that larger tires will improve ground clearance under all parts of the vehicle, including the axles and differentials—typically the next lowest points after the tires. While some vehicles can have larger tires added without a lift kit, such as a Ford F-250/F-350 pick-up truck which can usually take 33-inch (840 mm) tires before lifting is required, most will require a lift kit in addition to larger tires and, in some cases, bodywork modification such as cut back wheel arches may also be necessary.
Many off-roaders will combine different aspects of each of these vehicle lifting techniques, with the more experienced combining all of these items for a vehicle that could be lifted over 12 inches (300 mm) from its normal ride height.
One of the main aspects of off-roading is to be able to keep traction on different obstacles. This can be done with more aggressive tread on tires as well as with help from traction control devices in drivetrain.
Some traction control devices used are:
- Locking differential
- Limited slip differential
- Four wheel drive
- "Airing Down" – greatly lowering the air pressure in the tires
Dangers of vehicle lifting
While lifting a vehicle to gain ground clearance is helpful to off-roaders, it can also make a vehicle dangerous as, when a vehicle has been lifted, its center of gravity rises making the vehicle more likely to tip over in certain situations. Other dangers include loss of visibility of smaller objects and bumper height as compared to other vehicles on the road. In the United States bumper and frame height laws are in effect in most states to make sure that the vehicles on the road are not too much higher than their car counterparts.
A danger with off-roading is that of damage to the vehicle from rocks and gravel dislodged by the wheels. A common way to deal with the problem is to install skid plates, thick metal plates protecting vulnerable parts (such as the rear differential). Some manufacturers install skid plates as standard equipment on some of their vehicles. For many others this additional protection is available as an after-market accessory. Skid plates may be simple flat plates, but they may also be formed (by stamping or by welding multiple pieces) to protect shaped items like differentials. Fuel tank skid plates are a common factory option.
Probably the most common improvement for off-road use is the grille guard, which can be added with or without an improved bumper. These typically metal frameworks extend to protect the front grille, and potentially the headlights as well. One common type used on off-road pickups and SUVs is the "prerunner" style, with an angular, protruding front designed to sweep vegetation away from the vehicle centerline, and to deflect the vehicle from less movable obstacles. The grille protection system can be assembled piecemeal, or a one-piece winch-mount bumper with a prerunner bar and grille guard can be fitted. Bumpers designed for off-road use typically have added eyes or D-rings to assist in vehicle recovery.
Another common off-roading accessory, "rock rails" or "rock sliders", is a heavy metal rail which runs alongside the rocker panels and serves to protect the sides of the vehicle that are exposed to particularly rough terrain, so that there is a risk that lower edges of the vehicle between the wheels might come into contact with rocks below. This strategy can be extended to the entire vehicle, in which case it is referred to as an "external cage" or "exocage". External cages help protect the entire body of the vehicle in the case of a rollover or slide into an obstacle.
Criticism of ORV use
Off-road vehicle use on public land has been criticized by the U.S. government and prominent environmental organizations including the Sierra Club and The Wilderness Society. They have noted several consequences of illegal ORV use such as pollution, trail damage, erosion, land degradation, species loss, and habitat loss which can leave hiking trails impassable. ORV proponents argue that legal use taking place under planned access along with the multiple environment and trail conservation efforts by ORV groups is a solid step in avoiding these issues. Groups such as the Blueribbon Coalition advocate Treadlightly, which is the responsible use of public lands used for off-road activities.
According to the U.S. Forest Service the use of old-style two-stroke engines, previously common in vehicles designed for off-road use, also causes concerns about pollution. This is because "two-stroke engines emit about 20 to 33 percent of the consumed fuel through the exhaust" (as the engine lubricant is a "total loss system" and is emitted by design) and "discharge from two-stroke snowmobile engines can lead to indirect pollutant deposition into the top layer of snow and subsequently into the associated surface and ground water".
Noise pollution is also a concern and several scientific studies conducted by Montana State University, California State University, University of Florida and others have cited negative behavioural changes in wildlife as the result of some ORV use.
Some U.S. states have laws to reduce noise pollution generated by off-road and non-highway vehicles. Washington is one example: "State law requires off-road and other non-highway vehicles to use specified noise-muffling devices (RCW 46.09.120(1) (e) maximum limits and test procedures). State agencies and local governments may adopt regulations governing the operation of non-highway vehicles on property, streets, or highways within their jurisdiction, provided they are not less stringent than state law (RCW 46.09.180 regulation by local political subdivisions)".
Mojave desert controversy
The U.S. Bureau of Land Management (BLM) supervises several large off-road vehicle areas in California's Mojave Desert.
In 2009, U.S. District Judge Susan Illston ruled against the BLM's proposed designation of additional off road use on designated open routes on public land. According to the ruling the BLM violated its own regulations when it designated approximately 5,000 miles of off-road vehicle routes in 2006. According to Judge Ilston the BLM's designation was "flawed because it does not contain a reasonable range of alternatives" to limit damage to sensitive habitat, as required under the National Environmental Policy Act. Illston found that the bureau had inadequately analyzed the route's impact on air quality, soils, plant communities and sensitive species such as the endangered Mojave fringe-toed lizard, pointing out that the United States Congress has declared that the California Desert and its resources are "extremely fragile, easily scarred, and slowly healed".
The court also found that the BLM failed to follow route restrictions established in the agency’s own conservation plan, resulting in the establishment of hundreds of illegal OHV routes during the previous three decades. The plan violated the BLM's own regulations, specifically the Federal Land Policy and Management Act of 1976 (FLPMA) and the National Environmental Policy Act of 1969 (NEPA). The ruling was considered a success for a coalition of conservation groups including the Friends of Juniper Flats, Community Off-road Vehicle Watch, California Native Plant Society, The Center for Biological Diversity, The Sierra Club, and The Wilderness Society who initiated the legal challenge in late 2006.
Roadless area conservation
Many U.S. National Parks have discussed or enacted roadless rules and partial or total bans on ORVs. To accommodate enthusiasts, some parks like Big Cypress National Preserve in Florida, were created specifically for ORVs and related purposes. However, such designations have not prevented damage or abuse of the policy.
In 2004, several environmental organizations sent a letter to Dale Bosworth, Chief of the United States Forest Service, and described the extent of damage caused by ORV use, including health threats to other people:
It is well-established that the proliferation of off-road vehicle and snowmobile use places soil, vegetation, air and water quality, and wildlife at risk through pollution, erosion, sedimentation of streams, habitat fragmentation and disturbance, and other adverse impacts to resources. These impacts cause severe and lasting damage to the natural environment on which human-powered and equestrian recreation depends and alter the remote and wild character of the backcountry. Motorized recreation monopolizes forest areas by denying other users the quiet, pristine, backcountry experience they seek. It also presents safety and health threats to other recreationists.
Scalia noted that off-road vehicle use on federal land has "negative environmental consequences including soil disruption and compaction, harassment of animals, and annoyance of wilderness lovers.
A number of environmental organizations, including the Rangers for Responsible Recreation, are campaigning to draw attention to a growing threat posed by off-road vehicle misuse and to assist overmatched land managers in addressing ORV use impacts. These campaigns in part have prompted congressional hearings about the growing impact of unmanaged off road vehicle use.
The House Natural Resources Committee Subcommittee on National Parks, Forests and Public Lands held an oversight hearing on "The Impacts of Unmanaged Off-Road Vehicles on Federal Land" on March 13, 2008. A second hearing on off-highway vehicle (OHV) management on public lands was held by the Senate Energy and Natural Resources Committee on June 5, 2008. The Senate committee hearing was convened for the purpose of finding out why the agencies are failing to grapple with the negative impacts of off-road vehicle use on US public lands and what the agencies might need to start doing differently. For the first time in perhaps a decade, members of the Senate Energy and Natural Resources Committee grilled leaders of the Forest Service and the BLM about why off-road vehicle use is being allowed to damage America’s national treasures.
Taking center stage in the discussion was the "travel planning process", a complex analysis and decision-making procedure with the aim of designating appropriate roads and trails. Both the Forest Service and BLM have been engaged in somewhat similar travel planning processes now for years, but some of the committee members didn’t seem to think those processes were going along so well. "The BLM has identified travel management on its lands as ‘one of the greatest management challenges’ it faces," stated committee Chairman Jeff Bingaman, D-NM. "Likewise, the Forest Service has identified unmanaged recreation — including ORV use — as one of the top four threats to the management and health of the National Forest System. Despite these statements, it seems to me that neither agency has been able to successfully manage off-road use."
"Existing rules for managing off-road vehicles are not being enforced," Bingaman added, and the agencies are ignoring unregulated use "with significant consequences for the health of our public lands and communities, and adverse effects on other authorized public land uses."
Negative environmental effects caused by a motorcycle to a portion of the Los Padres National Forest.
Negative environmental effects that occurred when off-road vehicle drivers deliberately left the posted trail. Anza-Borrego Desert State Park.
- ^ http://www.fs.fed.us/recreation/programs/ohv/
- ^ http://www.sierraclub.org/policy/conservation/offroad.asp
- ^ http://www.wilderness.org/OurIssues/ORV/index.cfm?TopLevel=Home
- ^ 
- ^ http://www.lvrj.com/news/13702907.html
- ^ http://www.mnresponsiblerec.org/Library/reports/Off-roadvehicledamageinDuluth.htm
- ^ http://www.fs.fed.us/r10/chugach/forest_plan/FEIS_VOLUME_1/chapter3_p1feis.pdf
- ^ http://wilderness.org/content/addressing-ecological-effects-road-vehicles
- ^ url=http://www.wildlandscpr.org/node/258
- ^ http://www.ecy.wa.gov/pubs/0401007.pdf
- ^ a b Mojave’s Off-Highway Roads Found Illegal
- ^ a b Judge rejects federal plan for SoCal desert routes
- ^ a b c Judge rejects U.S. management plan for California desert
- ^ http://fl.water.usgs.gov/cesi/rkg_publiclandindicator_proj.htm
- ^ http://www.naturaltrails.org/pressroom/releases/2004/bos-rec-final.pdf
- ^ http://www.ens-newswire.com/ens/jun2004/2004-06-15-10.asp
- ^ http://www.peer.org/campaigns/publiclands/orv/index.php
- ^ http://resourcescommittee.house.gov/index.php?option=com_jcalpro&Itemid=27&extmode=view&extid=151
- ^ http://energy.senate.gov/public/index.cfm?FuseAction=Hearings.Hearing&Hearing_ID=ca2e6111-befb-b64a-8a55-3945b88b484e
- Man-made erosion, The National Trust (UK)
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