Science Fair Project Encyclopedia
Rally Navigation techniques, tips and tricks
A map is essential for rallying. In any form of the sport, you will be using a map, either a standard type of map such as an Ordnance Survey map, or one provided by the event organisers, which may be in the form of a road book or pacenotes .
For road rallying, standard published maps are generally used, and in the UK these are the Ordnance Survey (OS) 1:50,000 "Landranger" series, or possibly the more modern 1:25,000 "Explorer" series. Both of these series use the same national grid, and the information here can be used with either type.
Before attempting an event, it is worthwhile becoming very familiar with the maps you will be using, and understanding how features are represented.
To describe the course of a rally and the correct route that the competitor should take, the organisers will provide route information which will relate to the maps you are expected to use. These come in many forms, as listed below.
- Grid References
- Gridline sequences
Route information may be marked with the statement "coloured roads only". This is not some sort of apartheid, but a way of indicating that the route information given relates only to roads coloured on the map - many tracks and green lanes are not coloured (so-called "whites"), and may be ignored when plotting a route.
Sometimes a white is used to disambiguate a route - these will be drawn as dashed lines.
Sometimes a white may be part of the route. This will usually be stated in the route information, or else the route will work only if you use a clearly marked white.
A Grid Reference is the standard way of plotting a point on a map. These may be given to varying degrees of accuracy, depending on the requirements of the event. A standard grid reference has 6 figures, but occasionally 8 or 10 figure references will be given. Sometimes, whole, half or quarter grid squares are specified, and for these only a four figure reference is required. For the OS maps, the UK national grid is based on gridlines drawn at 1 km intervals. Each grid line has a unique number, but for clarity the map will only show the last two digits of the grid number. Since every 100 km these repeat, a two letter code is assigned to each 100 km square region to remove any possibility of confusion. Usually these are ignored, since it would be rare for a rally to cover more than this amount of area.
The grid numbers along the east-west axis are called EASTINGS, and the grid numbers along the north-south axis are called NORTHINGS. When giving a grid refernence, the Eastings are given first, then the Northings. A mnemonic for this is "crawl before you walk", though that may not help some!
A six figure standard grid reference provides a resolution to 1/10th of a grid square, which is 100 metres on the ground. The 1:50,000 map can be used down to 25 metres on the ground, which is where the longer references come in. For pinpoint accuracy - always needed for plotting on rallies - a romer is essential. This is a transparent ruler device which matches the scale of the map being used. By aligning the ruler marks accurately over the map, a pencil mark may be made at the exact spot given by the reference.
Example: Grid reference TL045672
TL locates the unique 100 km square on the grid - we can usually ignore it since we know which map we are using.
04 - this is the EASTINGS square
5 - this is a point 5/10ths further into the square - i.e. to the right of the grid line 04
67 - this is the NORTHINGS square
2 - this is a point 2/10 further into the square - i.e. below the grid line 67
10 figure references are used to resolve down to 25 m on the ground, and use decimal notation - 25, 50 and 75 meaning 1/4, 1/2 and 3/4 of the 100m value, e.g:
gives square 04, 67
point 5.25, 2.50
Tip: Remember that the exact route must be correctly followed on a rally. A popular trick with organisers is to use a 10-figure reference to guide the route around a small triangular junction in a particular way (usually the unexpected way). Chances are, a manned control will be placed within sight of such a route, or else a codeboard (unmanned control) on the 'wrong side' of the triangle which you will miss if you fail to follow the exact correct route. Either way you will collect a fail for an incorrect route, so it pays to be careful and accurate when plotting references.
Grid references are straightforward and unambiguous. For preplot information such as the locations of blackspots, cautions, quiet zones and give-way junctions, they are generally always the way such points are listed.
For the actual 'en-route' instructions, normal grid references are rarely used except on the top level events where speed is more important - mostly the organisers are trying to slow you down, so many ways of 'encrypting' the information has been devised.
A tulip is a pictorial representation of the route. Each junction along the route is drawn as a small diagram which shows the design of the junction, and the route to follow at that point. In their most straightforward form, the tulip will show the exact arrangements of roads at the junction, oriented with respect to the car or else to the map. A large dot shows which branch you enter along, and an arrow shows which branch to leave along ("dots and arrows"). Such tulips are incredibly easy to use, and if given the route in this form, you may not need to draw the route on the map at all.
Tulips are also used in road books on other types of motorsports events, such as stage rallies, classic runs, treasure hunts and so on. You are bound to come across them sooner or later.
Where things may get tricky is in the variety of cunning ways that organisers have found to make tulips a lot less edifying than those described above.
The first common trick is to leave out the dots and arrows. This makes tulips much harder to use - you will have to trace the route each possible way from a junction to see which further sequence of tulips fits. Sometimes this can take a while to find - there may be a sequence of T-junctions that can fit several different ways, but eventually there must be some disambiguating information in the route instructions, such as a crossroads that will only be encountered in sequence if the route is followed in the correct way. Novices often make the error of 'forcing' a route to fit the info they have, or blaming the organiser for making an error - this is in fact rare and it is usually they who are at fault for failing to take some subtle piece of information into account.
Another common trick is to draw the tulips in a generic fashion, rather than trying to illustrate the actual junction - using simple T drawings for example, no matter whether the junction is really a straight 90 degree T or not.
Things get really dastardly when alternate tulips are given, or maybe every third... You won't necessarily be told that this is what you have - you have to discover that for yourself! If you simply cannot make a tulip route work, try skipping every other junction. This sounds impossible at first but with practice becomes quite straightforward - and cracking the code is a fun challenge.
A herringbone is a form of route instruction where the course to be followed is represented as a straight line (the "spine") with all junctions and routes NOT to be taken shown joining and leaving (the "ribs"). So for example if the correct route arrives at a crossroads and the crew is to turn right, the herringbone will portray this as two ribs on the left joining at the same point, forming a 'V'. This means that the portrayal of a junction is purely symbolic, and does not represent its layout on the ground - a single spur on the right could mean that the route simply passes a turnoff on the right, or a T-junction where you must turn left. The interpretation will vary according to what actually exists at that point. Herringbones are easy to use in conjunction with a map. The key to solving a herringbone quickly is usually found by learning to read it as "leave one on the left, leave one on the right, leave two on the right..." and so on. Usually every junction is shown in strict sequence, and other tracks or "whites" may be shown as dashed lines which helps finding the correct route. More devious versions have been known.
Sometimes you may encounter route information that looks like this:
This looks diabolical but is quite easy to decode. Each number pair represents a gridline to be crossed by the route (either easting or northing, as they come) in strict order. In fact these are quite easy to deal with, but detail is important - a road can sometimes cross and recross a gridline in a tiny amount of space - both crossings must be listed but if you didn't quite spot it, it can throw out your plotting.
Things can get tricky if you happen to be in part of the map where the eastings and northings have similar values - in fact seeing this, an organiser might well automatically choose grid sequences for that part of the route just to make it harder. As with headless tulips, it may take several attempts before the one correct route becomes clear.
Listing only every other gridline is common too, as is giving them in roman numerals, or backwards... the deviousness of event organisers knows no bounds.
Occasionally you may get other things thrown into the list, such as 'ETL' or 'LC'. This corresponds to the map features Electricity Transmission Line, and Level Crossing. These can be very helpful in confirming or disambiguating the correct route.
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