Monday, September 6, 2010

Trail Difficulty Scales - Off Road ATV SUV

Nearly every offroading book I pick up has some kind of scale they use to rate how difficult a listed trail is to ride. The problem is that there is NO one standard rating system so every one is different and unless I want to make my brain explode by trying to "interpolate" between them I'm stuck using all of them in the master maps.

Some of the books simply use a 1 through "n" value and leave it up to the reader to visualize whatever they want (where "n" is anything between 3 and 10.) Or, use "ski-run" type descriptions for trails – you know "green circle," "blue square" and "black diamond" (which may or may not relate to: "Beginner," "Intermediate" and "Advanced".

The big difference between them is that they all attempt to rate different aspects of the experience (and there are many) depending upon the mind-set, compulsiveness and preference of the writer. One rates the trail, another rates the riders skill level and still another rates the vehicle. Some describe it in great detail, others show pictures and still others just leave everything up to the imagination.

Add to all this the facts that most riders over-estimate their abilities, simple confidence makes a big difference, perceptions change from moment to moment and weather can instantly change the whole trail makes one want to chuck the whole rating thing altogether. And no matter how specific you get, there is always the outlier which necessitates a "3 and 3/4ths out of 10" rating!

I think our OffroadingHome maps are fairly careful to delineate which of the rating systems any one trail is using in the pop-up description bubble for each trail. You'll see the source of the trail (i.e. book it came from) the difficulty rating and any other cautions available. The full description of each system is published in the "resources" section of the web site and I'll post them below for your convenience.

When you are submitting a trail for inclusion in OffroadingHome maps, please be careful to inform us which rating system you are using - I've noticed that most submissions have been using the one used by Peter Massey in his books.

There are a couple of other issues of which you should be aware. First is that it is a common practice to rate each trail based upon its most difficult portion. That is the only method which makes sense to people who are deciding whether or not they want to take it.

Most of the time there is no option to "go back" when you arrive at the surprise difficulty in which case one hopes there is a more experienced driver along who can help out while you "portage."

Secondly, there are tails for which a four-wheel drive vehicle is necessary – and unfortunately, that fact isn't always communicated well. OffroadingHome has begun including "4WD" in all of our templates which can be deleted if not needed, but there are older maps already published.

It has nothing to do with ability and everything to do with physics. Two-wheel drive machines must increase speed to overcome comparative lack of traction as slope increases. There are some trails that you simply won’t get up because they are too rough to travel at higher speeds.

Arriving at such a situation by accident, one hopes that you are not either: alone or that you all are riding 2WD machines. A person with 4WD may need to toe-rope you up the grade.

A third consideration has been necessitated by the growing use of side-by-side vehicles. Contrary to what the salesman says, and you'd perhaps like to believe, there are ATV trails which are more dangerous in a side-by-side – again, having nothing to do with being too wide and everything to do with physics.

The run-over-rise isn't the issue, the camber is. Being belted into your seat on the down-hill side of a talus-covered mountain slope dramatically increases your risk of tip-over due to the non-symmetric center of mass.

Airplanes and Space Shuttles are not immune to it, and neither are ATVs. Tight, steep switchbacks are much more difficult or even dangerous for side-by-side machines. What they taught you in your riders safety class is true – there is a big advantage in being able to shift your weight around on a single rider machine.

I kinda like the way the Western Montana Trail Riders Association puts it regarding the tendency of people to consider themselves better riders than they actually are:
Our job is to put our best effort into assigning the correct rating to any given trail. Your job is to determine if you are fully capable of riding that trail, remembering that: STUPID HURTS!

Below, are the various difficulty rating scales used in Offroading Home maps. I've thrown in a couple of extra that I find either unique or humorous. I especially like the Red Rock 4-Wheelers scale – those sound like some serious dudes!

Scale Used By Peter Massey

Adler Publishing (Designed with SUVs in mind) and used in the "__ Trails" series of books – designated like: "(rating)/10," and nearly always associated with a 1 to 10 scenic rating as well.
  • 1 - Graded dirt trail but suitable for a normal passenger vehicle. Normally with gentle grades, fairly wide track, and very shallow (if any) water crossings.
  • 2 - High clearance vehicles are preferred but NOT necessary. These are dirt roads, but not suitable for normal passenger vehicles due to rocks, grades, water crossings or ruts. Passing and mud are not a concern under normal weather and circumstances.
  • 3 - High clearance 4WDs are preferred but any high clearance vehicle is acceptable. Rough road surface is expected, mud and sand are possible but passable. Rocks up to 6 inches in diameter, loose surface, shelf roads wide enough for passing or pull-offs.
  • 4 - High clearance 4WDs are recommended, though most stock SUVs are acceptable. Rough road with rocks greater than 6 inches but with a reasonable driving line is expected. Negotiable mud patches, deep sand requiring lower tire pressures, up to 12 inch deep stream crossings, substantial sections of single-lane shelf road, moderate grades and sections of moderately loose surface are all possible.
  • 5 - High-clearance 4WDs are required. Rough, rutted surface, rocks up to 9 inches, mud and deep sand requiring experienced driver, 18 inch stream crossings are expected. There may be traction problems on steep sections, and shelf roads with steep drop-offs or tight clearance (for an SUV width vehicle) between rocks or trees.
  • 6 - Trail is for experienced drivers only and are potentially dangerous due to large rocks, ruts, terraces, stream crossings greater than 18 inches involving rapid currents or unstable bottoms or difficult access. There are also steep slopes, loose surfaces, narrow clearances, narrow shelf-roads with steep drop offs and possibly challenging surfaces.
  • 7 - Skilled, experienced 4-wheel drivers only. Very difficult trails with steep grades, loose surfaces, large rocks, deep ruts, and/or tight clearances. Winching over mud, sand or ruts is not unexpected.
  • 8 - 10 - There is likely damage to stock vehicles at this level and the trail may be impassable. Highly-skilled, experienced driver is required. These are largely beyond the scope of these maps.

Scale Used by Charles Wells

Funtreks, inc. (designed with SUVs and 4WD in mind) and used in the "Guide to __" series of books – designated by the name which is associated with a series of photos on their web site.
  • Easy - Gravel, dirt, clay, sand, or mildly rocky road. Gentle grades.Water levels low except during periods of heavy runoff. Full-width single lane or wider with adequate room to pass most of the time.Where shelf conditions exist, road is wide and well maintained with minor sideways tilt. Four-wheel drive recommended on most trails but some are suitable for two-wheel drive under dry conditions. Clay surface roads, when wet, can significantly increase difficulty or may be impassable.
  • Moderate - Rutted dirt or rocky road suitable for most sport utility vehicles. Careful tire placement often necessary. Four-wheel drive, low range, and high ground clearance required. Standard factory skid plates and tow hooks recommended on many trails. Undercarriage may scrape occasionally. Some grades fairly steep but manageable if dry. Soft sand possible. Sideways tilt requires caution. Narrow shelf roads possible. Backing may be necessary to pass. Water depths passable for stock high-clearance vehicles except during periods of heavy runoff. Mud holes may be present especially in the spring. Rock-stacking maybe necessary in some cases. Brush may touch vehicle.
  • Difficult - Some trails are suitable for more aggressive stock vehicles but most trails require vehicle modification. Lifts, differential lockers, aggressive articulation, and/or winches recommended in many cases. Skid plates and tow hooks required. Body damage possible. Grades can be steep with severe ground undulation. Sideways tilt can be extreme. Deep water crossings possible. Shelf roads extremely narrow; use caution in full-size vehicle. Read trail description carefully. Passing may be difficult with backing required for long distances. Brush may scratch sides of vehicle.

Scale Used by Tony Huegel

Wilderness Press (designed with novice SUV drivers in mind) and used in the "_ Byways" series of books – designated by the name.
  • Easy - The trail is a cruise that probably won't require using 4WD unless conditions deteriorate.
  • Moderate - The trail is slower going using 4WD at least occasionally, with rough spots, possible stream fordings, ruts, etc., but little or not technical terrain.
  • Difficult - Trail with at least some technical four-wheeling, rough and slow going in 4WD/low range, and the possibility that you will scrape the undercarriage or body panels.

Scale Used by Roger Mitchell

Track and Trails Publications (designed with SUVs in mind) and used in the "_ SUV Trails" series of books – designated by the roman numeral and accompanied by photo examples on their web site.
  • I - Semi-improved road, receiving little or no maintenance, over which you can drive a standard passenger car with little fear of damaging the undercarriage.
  • II - Road might have a high center, or an occasional rock sticking up, either of which could cause problems for ordinary passenger cars. Possibly able to be negotiated by a skilled driver operating a low-slung automobile, however two-wheel drive vehicles with higher ground clearance than most passenger cars is highly suggested. Four-wheel drive and dual range gears are not needed.
  • III - Possibly very rocky, very sandy, or very steep. Four-wheel drive may be required. A transfer case with low range gears and locking axles is not needed. Unless they are excessively wide, most off-the-shelf SUVs and pickups, even with novice drivers, should be able to handle this road without any vehicle damage.
  • IV - Unsuitable for most stock SUVs and recommended only for fully experienced drivers. A transfer case with ultra low-range gears is necessary, as is at least one full-locking axle, skid plates protecting everything vital underneath, and oversize tires of at least 33 inches which can be easily deflated and inflated on the trail. Minor vehicle body damage could occur. An outside spotter may be needed.
  • V - Extremely difficult and unsuitable for stock vehicles or even moderately experienced drivers. The following items are a must: A transfer case with low range gears, two to four-inch lift of the suspension, locking axles both front and rear, skid plates protecting the entire undercarriage, roll bars, and a winch. Even with a spotter, some vehicle damage will occur. Again, look at the photos of this rating: Mitchell Scale.
  • VI - Extreme and hard-core. In addition to the equipment and modifications listed above, a full rigid cage is recommended. Even with an experienced driver in a highly modified vehicle, the chances of a rollover are quite high!

Western Montana Trail Riders Association

Western Montana Trail Riders Association (Designed with ATVs in mind) and used on their web page.
  • Easy: These routes are for Beginning Riders or those with very limited experience. They are best suited for families with younger riders and others not seeking a challenge. You will be riding mostly on gravel Forest Service roads and other two track dirt roads having gradual to moderate grades. These roads have very few, if any, obstacles, challenges or off-camber situations. Because these routes are easy, they tend to provide great opportunities for enjoying the scenery.
  • Moderate: These trails are for Intermediate Riders having a higher level of experience. These trails are for those who have gained a greater knowledge of their own abilities and a better understanding of their machine’s capabilities. This type of riding would more likely be on actual trails or narrow two track roads rather than graded, mostly level, forest service roads. Typically, this type of trail would be rougher and somewhat steeper. You may experience water crossings, some rocks, a few ruts, exposed tree roots and some mud along the way. You may encounter moderate switchbacks and/or tight corners requiring more control over your machine. These trails are for riders who are ready for a step up in difficulty and desire a moderate amount of challenge on their ride.
  • Difficult: These trails are for Advanced Riders. To ride this type of trail you should have full knowledge of your machine’s capabilities and feel fully confident of your own abilities. Typically, the advanced rider has a lot of time on their machine and spends a considerable amount of time riding challenging trails. You should be comfortable with steep grades and significant off-camber conditions. Trail conditions can include large rocks, deep ruts, moderately deep water crossings and tight, steep switchbacks. Difficult trails may also include snow at higher elevations. Advanced riders often like to ride these trails at a faster pace and enjoy the challenges that difficult trails offer. These trails will often require four-wheel-drive.
  • Very Difficult: These trails are for Expert Riders. Almost every aspect of this type of trail makes them just that much more difficult and challenging. You will experience even steeper grades and major off-camber situations requiring all your weight to be moved to one side of your machine. Generally, these trails will have even deeper ruts, can include water, mud and/or snow, are often much rockier and can have tighter, steeper switchbacks. More often than not, this type of trail will include many or all of these challenges. Trails with this rating can take you up into higher elevations. A winch is often necessary to get through these trails and spotters are often required to help you up, down, over or around various obstacles. In general, these trails can be dangerous for anyone other than an expert rider. Four-wheel-drive machines with a winch are mandatory for these trails.

Scale Used By Red Rock 4-Wheelers

Red Rock 4-Wheelers (Designed with ATVs in mind) and used on their web page.
  • 1 - All weather road; 4WD not needed.
  • - Graded road; 4WD may be needed in poor weather.
  • 2 - Unimproved or rarely graded road. 4WD or extra clearance needed at times, with no special driving skills required.
  • - Road rarely maintained, 4WD, good clearance, low gears often needed, with some extra care and a bit of driving experience useful.
  • 3 - Road in difficult terrain, rarely maintained, 4WD, good clearance, and low gears essential, with some driving skill and daring required.

  • Ah, this is obviously some strange usage of the word 'safe' that I wasn't previously aware of.”
    Douglas Adams, "The Hitchhikers Guide to the Galaxy"

  • - Road in difficult terrain, probably maintained only by occasional users. Excellent stock truck or utility vehicle required, with considerable driving skill and daring needed.
  • 4 - Trail either never bladed or badly eroded. Stock vehicles are in jeopardy. Modifications for improved off-road performance and top driving skills needed.
  • 4+ - We can hardly improve on the original description written a few years ago by Jack Bickers: driving by World Class Yahoo Jeepers not much concerned with vehicle durability or personal safety! It is common to have as many as 10 percent of the vehicles experience major mechanical failures (gears, axles, drive shafts) on these trails.

Scale Used By Idaho Dirt Bike Trails

Idaho Dirt Bike Trails (Designed with dirt bikes in mind) and used on their web page.
  • 10 - Expert Advanced - Some examples would be: long, steep, rutted climbs or descents over terrain, covered with rocks and roots; narrow side hill trails traversing steep, mountain sides; or tight switchbacks that turn steeply over embedded roots and rocks. The kind of obstacles that only the most outstanding riders can ride over without paddling or pushing. The kind of obstacles where if you make a mistake riding them, it will mean serious injury or worse. A trail that fits as an example here would be riding up the Lodgepole Creek Trail in the Boise National Forest. A trail Dave said was the “hardest trail I have been on to date.”
  • 9 - Advanced - You’re still dealing with rocks, roots, creeks, trees, brush, ruts, and every other obstacle on steep terrain. It’s just not quite as life threatening, and a little easier to push or pull over if you can’t ride it. Going up the Venice Creek Trail in the Sawtooth National Forest is an example that comes to mind. It has some 2 - 3-foot root steps to get up, some steep switchbacks and plenty of rocks. But you would be able to push up it easier than a trail like Lodgepole.
  • 8 - Advanced Intermediate - Just a shade of gray down from Advanced, but a little less extreme on the danger scale. A little less steep and long, and the rocks, roots and creeks are more navigable. Still, you need to be a good rider to handle this kind of stuff. The Grassy Mountain Lakes Trail in the Payette National forest is a good example for this level. It’s about five miles of non-stop climbing up a mountain, followed by a descent down a steep shale side hill. (I would classify Robber's Roost, on the Boundary Trail at this level, sorry no data on this one yet. --Rod)
  • 7 - Upper Intermediate - A notch down the difficulty dial again, but still all the common obstacles are likely encountered. The Charlie Kouba trail near Idaho City is a good example of this level.
  • 6 - Middle Intermediate - You still got your single-track with some rocks, roots, ruts, and trees as possible obstacles. But the trails are better groomed and traveled, with less treacherous obstacles and hills. A trail that fits this mold is the Yellowjacket trail in the Boise National Forest.
  • 5 - Lower Intermediate - Trail 500 at Black’s Creek is a good example trail for this level. There aren’t any trees or roots, just some sage brush. The rocks are fewer as well. What you do have are some decent hill climbs and descents on rutted, whooped, ATV trails. A good trail to start developing hill climbing skills.
  • 4 - Advanced Beginner - Riding to Silver City from Rabbit’s Creek comes to mind here.This is all four-wheel drive roads, with some minor hill climbing and ruts and rocks to deal with.
  • 3 - 2 - Middle Beginner - This is the first kind of cross-country trail new riders can handle once they have learned to shift, throttle, and brake a bike. Trail 100 from Hemingway Butte to Rabbit’s Creek is a good example. It is an ATV trail with very mile ups and downs and no real obstacles along the way.
  • 1 - True Beginner - This is a flat area like a the parking area at Hemingway where someone just learning to ride won’t have to worry about running into anything, or over anything. This is where you learn to use the clutch, shift, and use the brakes.

Scale Used by Ascent Services

You will notice a few (about 42) trails in Utah with minimal information and/or actual tracks. They come from a pamphlet sold in Utah called "Ridin' the Utah Trails" which turned out to be pretty much nothing more than a collection of trailheads and their waypoints.

The rating systems are not standardized except allowing everyone to come to their own conclusion about what "easy, moderate and difficult" might mean. The maps are line squiggles on a featureless grey background without any labels and they've thrown in a couple of unlabeled photos to fill out the page.

It's the only thing put together specifically for ATVs in Utah so it's sold almost everywhere for a hefty price with a warning from the publisher (you guessed it not available on the web) disclaiming its accuracy and advising to go to a specific local store and pay for a map.


Ron, Lori, Lacey, & Riley said...

Dr J, I enjoy your blog and am subscribed to it by RSS feed. No need to post my comment, you probably already know this, but I just wanted to alert you that Red Rock 4 Wheelers did a full makeover of their rating system 2 years ago. It is completely different than the old system and it isn't an easy conversion from the old to the new either. The new updated rating system is at

Dr J said...

Ron et. al. -- Thank you for the update. I have to confess that I did know they had updated their rating system - which doesn't look at all like their old one. Also, it was one of the scales which I mentioned I only included because of its interest (Offroading Home hasn't had any trails submitted using that rating scale) - I really liked the way they put their highest rating. Keep reading -- and send in some of your tracks (from reading your blog it looks like you get out and about once in awhile.)

Post a Comment

Thanks for taking the time to leave a comment. I will, of course, be moderating all comments to make sure (a) they conform to the standards of good taste set forth by Offroading Home; and (b) nope that's pretty much it.