Using Maps While Bicycle Touring

Very few people would go on a long bike tour without carrying a map, although they could depend on road signs and instructions from locals instead, something that must often be done anyway. But although everyone carries a map, not everyone can read a map equally well.

It's easy to underestimate the power that maps give us. They allow us the opportunity to scout over a vast amount of countryside and roads and thus allow us to pick the best routes and to predict what we would find along those routes before we get there. However, the power of the map to reveal information depends on the ability of the reader to recognize both given and inferable information.

I will not attempt to supply complete map-reading instructions to save myself a great deal of work, to avoid boring those who can already read the given information on maps, and to avoid repeating what has been done better elsewhere, but instead I will focus on inferable map information useful to the bicycle traveler and/or trip-planner.

Kinds of Information on a Map

There are two kinds of information on a map: given information and inferable information. Given information is either stated or represented by a symbol; for instance, the population of a town can be given as a number, or the symbol used for the town might indicate a town between 5,000 and 10,000 population. Inferable information is information that is neither stated nor indicated with a symbol but that can be figured out from the given information on a map. An example would be the amount of traffic on a road. Of course, information inferred from the map is softer information than given information; that is, it is not as precise and is less dependable. However, most of the information we use in bicycling does not have to be precise but crudely approximate; for instance, the exact number of vehicles per day on a road is unimportant; we just need to know if we will be comfortable riding there or not. Even with the exact data, because the traffic varies from day to day and hour to hour, we still would have the problem of inferring what the flow will be like while we are using the road. I have become so adept at inferring information from a map that I usually don't ask the locals for information, although I recommend asking anyway to be on the safe side, preferably asking two or more people. Often, however, locals can't tell me information that I can plainly see on the map.

Available Maps Which a Cyclist Might Use

Before looking at inferable information further, let's look at what kind of maps are available, going from the most detailed to the least detailed, pointing out here the given information these maps provide. If you're familiar with all the available types of maps, you can skip this section.

Topographic Maps

The map type with the greatest amount of detail is the USGS topographic map which comes in various scales and sizes; however, two sizes are much more common than the rest. The most common is the 7.5 minute scale map, which covers an area about 8 miles wide and 8 miles high (topos for the higher latitudes are narrower). Due to the limited area, 7.5 minute maps are not useful for touring, although they are great for hiking and mountain biking. The 7.5 minute maps show houses, tiny streams, 20 foot contours, and wooded areas. Physical features are often named: "McBroom Hollow," "Bee Branch," "the Buzzard's Roost." These maps can easily be used to calculate the exact height and grade of a climb. Since the topographic information for these maps comes from stereoscopic aerial photos, with little field checking, they do contain errors. The next most common size is the 1:250,000 topo map, which covers an area about 70 miles high and 140 miles wide. These maps are more useful for touring, but their extent is still rather limited for long-distance travelers. These maps do not show fine detail or name features, and the contour interval is 200 feet, providing less information about hill climbs. Both kinds of topos have good information about the condition of the road, but neither is frequently updated, so the highways might have changed since the map was made.

Al Davis provided some information to touring@phred.org about the GTR maps, which are available only in the Northwest. Since I haven't seen one, I asked his permission to quote him here. He wrote

For the US rocky mountain states, I really like the GTR maps. (http://www.gtrmapping.com) Get the "recreational" maps, at cost $3.95 . These maps are works of art, far superior to the Michelin maps. The map itself is on one side. It shows any roads a bicyclist might want, including the dirt ones, and it shows the surface type. It shows contours, and is color coded to show elevation. It shows where campgrounds and points of interest are. On the back, there is a list of facilities, including campgrounds and where drinking water is available.

By "campgrounds" here, I mean anything a bicycle tourist would consider using. If it has 2 sites, and you can't drive to it but can bike to it, they show it. It does not show the commercial "Kampgrounds", but emphasizes the free public ones.

National forest topographic maps are especially useful for finding camping and/or mountain biking areas, as they show which land belongs to the national forest and also any other government land in the same area, such as land belonging to the Bureau of Land Management. Unfortunately, there is no central office which sells these maps, so they can only be purchased from the regional national forest.

More useful for a long-distance cyclist (although not showing land ownership) is a state atlas, which contains topographic maps or county road maps covering an entire state. Delorme's atlases include complete topographic coverage. The topographic details are about 1:180,000 scale, contours are at 120 feet, and shading is added to topographic features to make elevations more apparent, but there is scant information about the quality of the roads. I also have an atlas made for the state of North Carolina which is based on county maps and has their advantages and disadvantages, see county maps below. Both of these atlases are too large to carry well on a bicycle (about 11" by 16"). No one could carry all the atlases for a cross-country trip. However, the useful local information makes them very worthwhile for touring within a state. On my bike trips, I purchased these atlases in Pennsylvania and North Carolina while I was exploring back roads.

Computer Maps

Another choice is the computer street atlas or the computer topo map series. Both of these types of maps are scalable (can be view at different scales), but at some scales the maps may be confusing. Some versions are small enough to fit on the hard drive of a laptop; however, the topo map series (by Delorme) requires carrying four to seven CD's, depending on the version. The Delorme Street Atlas shows wooded areas in green and lots of local information plus all the roads but lacks the topographic detail of the topo series. The Microsoft equivalent shows roads more accurately but fails to mark wooded areas or to name local features. Some other computer maps, such as Delorme's Map and Go, provide tourist information (such as restaurants and motels), but do not include every road. None of these maps indicate information about road surfaces. There are also maps of this nature available on the internet. With all of these computer maps, you can print your own strip maps before your trip if you don't wish to carry the computer; however, printing the exact map you want may be difficult.

County Road Maps

The map that focuses on road detail is the county road map, which can be purchased from the Department of Transportation in each state. Usually, a free county map can be found at the court house. These maps exaggerate the width of the roads to provide room for road surface information, and they show all county, state, and federal roads within their area; however, they often omit city streets, due to lack of space. These maps are excellent for exploring back roads, as they not only show the roads, but they also show the condition of the roads, whether dirt, gravel, thin pavement, or fully paved (other categories are possible). They often show houses and usually churches and cemeteries. They fail to show forests and may or may not show hills, but they usually show all streams. These maps are a great help to the local traveler, but they are impractical for the cross-country traveler, as too many would have to be carried.

Free Special Maps

Very useful are the free, detailed non-topographic maps produced for many parks, forests, natural areas, and special routes. The map for the Blue Ridge Parkway is the map of this kind that I most often use. It shows every overlook and picnic stop and all the campgrounds plus provides some information about the climbs. A number of the other maps I have encountered are similar in style and information to the parkway maps, but there's a wide amount of variation in the material presented. Free forest maps, for instance, are often similar to county maps. These maps can often be found at rest stops, information booths, and ranger stations.

Bike Route Maps

The Adventure Cycling Association (formerly Bikecentennial) has created strip maps for all of its routes across the US, which include three coast-to-coast routes, routes along the Pacific and Atlantic seaboard, the Mississippi River, the Rocky Mountains, and to Alaska. A new connection has just been added between Pueblo, Colorado and San Francisco. These maps provide topographic map information but are too narrow to allow exploration off of the route. Following the maps can be aggravating in some states due to frequent turns, and the routes tend to wind around on obscure back roads whenever possible, hitting all the hills. Forest coverage is not shown. However, no other map shows every small grocery store, bike shop, campground, and feature of interest or plots a complete cross-country course.

A number of states offer cycling maps. Some of these are based on the automobile road map below and have the roads marked in color to indicate their desirability. The best of these that I've seen is the Colorado map, which rates the roads according to traffic volume and shoulder width and which provides additional detail when necessary. Others are strip maps similar to the Adventure Cycling maps. The best of these that I've seen is "Tennessee Bicycling Highways" produced by the Tennessee Department of Tourist Development. These maps lack topographic detail and information about stores, but the maps are carefully made and easier to read, and the instructions provide extra detail.

Road Maps

Finally, the most common map is the regular highway road map. Back in the 60's and earlier, these maps were free from the gas station, but now they cost as much as $5 each (and haven't gotten any better). The amount of information and sometimes the type of information on them varies widely from one company to another. Even on the same company's maps, more roads and details are shown in isolated areas than in congested areas. The larger and/or more expensive maps do not necessarily show more detail. On the best maps, the cartographers have been careful to preserve information that would otherwise be lost due to the small scale, such as bends in the road or unusually-shaped road junctions by enlarging those details and thus distorting the overall scale (this is done with county maps as well). Road maps are best, of course, in marking out various routes. There is a tendency (stronger in some states than in others) for the roads used by a route to be of equal quality. Usually, a road map will mark the routes with differ colors or different widths of lines according to their importance.

What Kind of Inferences Can Be Drawn from a Map?

In the rest my discussion, I will be talking mostly about road maps, as they provide the least amount of given information, require the greatest number of inferences, and will be the maps used by cyclists 90% of the time. However, my discussion will be useful for inferring details from all of these maps. Please understand that inferring information from maps requires both knowledge and experience, so you won't become an instant expert based on what I say. However, if you become aware that the information is there and you use your maps intelligently, you will gradually see more and more when you look at a map.

When looking at road maps, let me emphasize that different map makers have different policies for drawing their maps. This means that the inferable information and the conclusions that can be drawn will vary from map to map and map maker to map maker.

Even though regular road maps do not usually supply the following information, it is possible to infer from them: 1) the condition of the road, 2) the amount of traffic, 3) the presence of hills and mountains and the steepness of grades, 4) the presence of woodlands or other unimproved land that can be used for camping, and 5) opportunities for food and water. Note that inferred information of types 1 & 2 will vary from state to state due to differing policies and that 3, 4, & 5 will vary from region to region due to different terrains and climates. Let's look at the need for each kind of information and how we can infer that information from a roadmap. Then, afterwards, we will look at some general problems:

Road Conditions

The Problem: It's important to know in advance whether a road will be well-paved, have shoulders, or other advantages and disadvantages. A good road map does differentiate between routes by showing four-lane roads with double lines, main two-lane roads with red or wide lines, less important two-lane roads with either black or narrower lines, and the least important roads with gray lines (in my examples below, I will use a thin black line because it is easier to see). However, the map-maker does not indicate the age, the condition of the road, or whether it has shoulders or not, details important to the cyclist.

Making the problem more complicated, each state has its own policies as to which kinds of roads will be left unpaved, which will receive gravel, a light pavement, or heavy pavement, which will get shoulders, and how well the roads and shoulders will be maintained. In one state, every road of any size has wide, well-paved shoulders; in another, paved shoulders just do not exist. In one state, every road looks as if it was paved recently; in another, the roads have not been repaved in nearly 50 years. Therefore, you have to readjust your inferences for every state. The need for this readjustment is sometimes obvious the minute you cross the state line.

To further confuse us, in every state new roads are being built and some, but not all, of the old roads are being upgraded to current standards. Therefore, most states have a "then" and a "now" road-building policy, "then" based on what the road policies were when that particular road was being built, and "now" based on current policies, which apply to new roads and rebuilt roads only. This especially affects road shoulders, as in most states the newer sections will have excellent shoulders, older sections will have poor shoulders, and the oldest none, even if on the same highway.

Finally, in some states, all of say Route 5 will be of the same quality, while in another state, Route 5 will vary from road intersection to road intersection, according to the amount of local traffic.

I have found that asking motorists about the presence of shoulders and the bicycleability of a road to be almost a complete waste of time; they don't paid attention to such details, and they are likely to reroute you onto to the most dangerous roads ("Highway 5 is terrible, with lots of sharp turns, stop signs, and holes, but Highway 6 is straight with good passing lanes, and you can average 15 mph over the limit with no problem.")

The solution: In order to predict the condition of the road, you have to combine what you know about state policy with the information on the map. Size and age are closely related to state treatment of the road, and size is partially determined by the road's status (marked on the map) and partially by the volume of traffic, discussed below. In order to predict the age of the road (which tells you which state policy applies), you have to look for secondary indicators, such as the straightness of the road, whether it passes through towns or not, and whether it has interchanges or not. When building roads years ago, the policy in hilly areas was to follow the natural terrain, and thus old roads are indicated by including lots of little bends. In perfectly flat areas, the older roads run between the property lines, and thus travel due NS or EW with 90° turns whenever necessary. Modern roads tend to travel as straight as possible from A to B, ignoring local terrain and property lines. The older roads ran from town to town and were lined up to hit the main street of every town. Newer roads run from city to city and bypass the towns (and often cities too). Older roads had level crossings at every intersection; the larger new roads incorporate cloverleafs whenever possible, and these are often indicated on the road map with little squares. Thus you can predict the age of a road by comparing its behavior with nearby roads and from that (and knowledge of that state) predict its condition and other features.

Please note that I am not suggesting that the most recent roads are necessarily the best. While they are more likely to have shoulders, they are also more likely to have steeper grades and faster traffic. It really depends on state policy. Also, even the best prediction won't be right every time, but a prediction can be extremely helpful and can make the difference between crossing the state and giving up in disgust.

Traffic

The problem: Traffic is more variable than any other factor. The time of day, day of the week, day of the year, season, and weather all cause fluctuations while everything else remains the same. Traffic is also greatly affected by population density, per capita income, location of industry and stores, long-distance trucking, and tourist traffic. Light-duty roads may receive heavy traffic while superhighways can be empty.

The solution: Traffic is very easily inferable from the map, but not from the thickness of the highway lines. Basically, there are three kinds of traffic: long-distance trucking and tourist traffic, commuter traffic, and local traffic, and each has its own causes and times, and thus must be inferred separately.

Long-distance traffic confines itself to the interstates whenever possible; however, if a good highway connects major cities together without an interstate alternative, it will receive lots of through traffic, especially trucks. Watch out also for highways (and sometimes roads) leading from cities and industrial areas that feed traffic into and off of an interstate and for roads that can be used as short-cuts from one interstate to another. Holiday and weekend long-distance traffic is the worst, especially football traffic. Fortunately, long-distance traffic confines itself to the highways at all times, so use a back road when you encounter it.

A second kind of long-distance traffic is tourist traffic. In a well-developed tourist area during tourist season, there will be lots of cars, SUV's, vans, and RV's. You can spot these places on the road map because the special attractions will be well-marked. Native American names for places are a dead give-away. It's best to avoid tourist areas, if possible, as prices will be high, free camping impossible, and the traffic often heavy. Tourists are both better and worse than other motorists; they are better because they are usually in less of a rush, and they are worse in that they are often traveling in seldom-used, oversized vehicles.

Commuter traffic is largely time-sensitive. Roads which skirt cities or which connect the cities to the boondocks, especially those that feed off of interstates will have light traffic most of the day and very heavy traffic during the morning and afternoon rush hours. The farther from a city a road is, the earlier and later the rush hour on that road. Also expect heavy evening weekend traffic, as the commuters drive back into town for recreation. Since commuter traffic is so time-bound, the best way to avoid it is to avoid commuter roads at certain hours of the day.

Local traffic is quite predictable from the populations of the towns along the road. All other things being equal, the traffic on the sole road between two cities of 50,000 will be a hundred times as heavy as the traffic on the sole road between two towns of 500. In addition to urban traffic flow, we must include rural traffic. In good farming areas, the farms will be large, and rural traffic will be too light to measure, but in areas where farming is not profitable, people spread out all over the countryside, and the rural traffic is considerable.

Hills, Mountains, and Grades

The problem: Hills and mountains can make a bicycle touring trip difficult or impossible, yet they are usually not marked on a road map. In the East, steepness is often a greater problem than height.

The solution: While it would be wise to consult an atlas before making the trip, it is possible to spot hilly and mountainous areas by looking at a road map, even on maps that don't indicate such features. In addition, by looking at a road map, we can often spot steep climbs, and we can often predict which of two routes will have the steeper grades. Flat areas have straight roads, hilly areas have roads that wind around and follow the terrain, and in the mountains, some roads following the valleys up and others the ridges, but both must wind with the terrain. Only the newest, most expensive roads ignore the terrain and depend on huge causeways, embankments, and ramps. Generally, if two roads climb the same mountain, the one with the greatest number of sharp curves (switchbacks) will have the flattest grades. Newer roads usually climb straight up the mountain while older roads, to avoid steep grades, wind around. Look for streams too, as a road following a winding streambed is following a natural cut through the mountain.

Woodlands and Unimproved Lands

The problem: Road maps can often mislead you if you are looking for a place to camp. The map shows green national forest land, but when you reach the spot, you find nothing but fields, with no woods in sight. The problem here is that many national forests have just tiny amounts of land, spread out over a large distance. On the map, the whole area is marked as national forest when perhaps only the mountain tops are.

The solution: The best solution is a national forest map; however, it's often possible to predict from a road map where you will encounter woodlands and other unimproved lands. The most likely places for camping are in sparsely settled areas along streams and lakes and in the hills and mountains. Even with a forest map, one has to predict where the ideal camping spots will be. Indications as to the steepness of hills can be useful too, as your camping site can't be on highly sloped ground.

Opportunities for Food and Water

The problem: Road maps don't show where to get food and water, yet you can become awfully hungry and thirsty while riding a bike. Making the matter worse, there is currently a tendency for local stores to have to close for lack of trade while the locals to drive long distances to discount stores and supermarkets. Of course, you always have the option of stopping at any house for water, but most homeowners are gone during the day nowadays, and the ones still at home are likely to be hostile, suspicious, and unhelpful if you should pound on their doors.

The solution: In some areas, grocery stores are found only within communities, while in others, there's a mom and pop store at every intersection. In any event, a store must depend on traffic, so the sections of road with the greatest amount of traffic are the most likely places for such a store. As intersections receive traffic from two roads at once, these locations are highly favored.

With a water filter, you can get water from a stream; however, you must avoid river water which is highly contaminated with industrial and human wastes. Lakes, small streams, and mountain springs are the best best.

Sample Maps to Demonstrate Problems and Solutions

Sample Map One

What can we tell from this map? First, we can see that roads A, D, and F carry the most traffic and are probably the most recent as well. The markings for these roads tells us that they are important roads and their straightness, when the other roads are a little more crooked, tells us that, plus we can see that they are not blocked or interrupted by other roads. On the other end of the spectrum, roads C, G, and E are the least important. C is not allowed to even connect to the biggest road, D; G either travels only a short distance, or the rest of it is not marked on the map (I spend a lot of time on roads which don't appear on roadmaps); E is the older road which D replaced. B, like E, is an older road which no longer carries the most of the traffic. The straightness of the roads tells us that there are probably no grades worth worrying about, although there are some hills; a hill or streambed is indicated where D and E turn (notice that E is irregular in shape here). The best place to find a place to camp is probably along E, especially near the turn. The best place to find food and water would be at the intersection of A and D or A and F or along the road between them. If I was traveling through here, I would choose to travel on B, C, or E, because I prefer to have the road to myself and because lightly-traveled roads usually present more camping opportunities. On the other hand, A, D, and F would be most likely to have shoulders, depending on state policies, and they would be more likely to have motels, especially near major intersections.

Sample Map Two

With this map, we see evidence of mountain terrain. The gradually curving roads, C and D, are probably traveling along a valley floor. In the east, A and B seem to be in a valley floor as well, but to the west, we are seeing a mountain, indicated by the sharp turns on B. Evidently, B is winding its way up the mountain while A is climbing on a huge ramp. The flattening of the two roads in the extreme east (and I say they're flatter because they are both straighter) is probably due to a plateau, although the two roads could have descended to a valley floor(the turns and straightaways on B are rather odd and could be interpreted either way). Why couldn't I say that B goes over the mountain while A goes around it? Well, it's obvious that B is the older road, and if there had been a way around the mountain, it wouldn't have climbed over instead. The best place for food and water would be on C between A and where B turns to climb up the mountain, although there might be something on D at the intersection. There are no services on A, of course, because it is an interstate. D would have the lightest traffic, and C is a feeder into and off of the interstate. B should have light traffic, but has evidently been kept open over the mountain because some people are living along it. I would expect the best camping to be along B in the mountain. Not all of B is equally steep, and probably the straighest sections are the flattest. B is very likely to be a rough road, especially over the mountain. (The odd turns on B, by the way, are due to MS-Paint, which is the worst program I ever tried to draw a curved line with.)

Sample Map Three

I drew this map just to demonstrate a problem created by interstates, and thus I won't be discussing other factors. The terrain is as flat as a board. On this map, we can quickly spot roads B and G, running north and south, as having the least amount of traffic. However, B has two interchanges and is likely to be used as a short cut by motorists traveling north on E and planning to travel west on C (or traveling east on C and planning to proceed south on E). B will also be used by local motorists traveling to and from the interstate. Therefore, G is a much better choice for north-south traffic. D might be a better choice than B because it has probably been designed for the extra traffic and likely has good shoulders. This depends on the state, the age of the road, and other factors, which we can not determine from the map. H is not a good alternative, because it will receive interstate cut-off traffic just as B does.

Sample Map Four

This map is focused on traffic patterns. As you can see, there are two small towns along road D, one indicated by a hollow circle and the other by a circle and dot (which means it's a little larger). There are two larger towns (or small cities) indicated by the yellow blur. A and B are through roads carrying at least some long-distance traffic. Based on this, we can make the following predictions: Traffic will be lightest on road D, heavier on E and F, and heaviest on road C. C might be a good route between the two cities nonetheless, because B will be carrying most of the traffic. However, since B is the newer road, it might have a good shoulder while C will have none, and thus might be a better bet, if you don't mind the higher traffic speeds. Which is better, E or F? Well, E is going to pick up some traffic going between A and the western city, so F would be the best route traveling north or south.

Sample Map Five

This map probably looks very odd to someone coming from a flatter area. Obviously, this map does not demonstrate flat terrain; however, some parts of the terrain are flatter than others, which the roads demonstate. This map is loosely based on an actual place which I have cycled through frequently. It is an area of valleys, small ridges, and plateaus, common along the Appalachians and Cumberlands. The only thing odd about the map is the valleys running north and south, as they usually run NE and SW. I admit to changing the orientation to make drawing the map easier. Well, what can we make of it? Interstate B must run through a fairly flat valley, as service road A is almost straight (the straightness of the interstate doesn't mean as much, as the DOT's are willing to build huge ramps and embankments). It looks as though C and E are on fairly flat terrain as well, and D is on somewhat less flat terrain. F and I are not as crooked as we would expect if they were each climbing a ridge. On the other hand, they are much too crooked to be on flat land. Highway I is not important enough to cut through a major ridge. Actually, F and I are both following streams that cut through the ridge, and I is following the larger stream cut, thus it bends less. The curves on G and H are due to climbing a mountain, and D is the road on the top, which is on top of a rolling plateau. However, road D could be following a ridge for all we know. The best places for food and water would be at the intersections of B and I and of C and I, with another opportunity at the junction of I and D, which is off of the map. In actuality, there is food at all of these places, the junction of B and I having fast food, C and I having supermarkets, and I and D a country store. The best places for camping would probably along F, G, and H, with some opportunities where highway I climbs the mountain. All of these roads are bicycleable, but highway I gets a lot of truck traffic both ways and is very uncomfortable at times.

Conclusion

Keep in mind that information from inferences is not going to be correct 100% of the time. The straight road, for instance, can cross a ridge or the road around the edge of the lake can be all up and down hill because the lake was created in hilly terrain. Still, it's very useful to be able to make some guesses about what lies ahead.