The rules below are paraphrased but not intended to infringe on any copyrights held by Steve Jackson games or anyone else. The work below is for educational purposes and many quotes are taken from Far Trader. The steps use Gurps world statistics so a conversion from Traveller CT style statistics to Gurps stats must be done first. The below is what is included in Far Trader with some modifications as put forward by Jim MacLean, the designer of the trade rules. Also included are my attempts at clarifying some of the less obvious points. Blame any poor wording on me alone and let me hear from you. I am Terry Mixon and you can reach me at tmixon@houston.rr.com. Several new terms are introduced in this text to avoid using the same word to describe two differing things. Route: The level of trade between two worlds. Path: The exact course that the trade route follows. Leg: Each step from world to world on the path that the trade route follows. To start, you need to know the World Trade Number. Follow the steps below to figure that out. 1. Determine Unmodified World Trade Number (UWTN). UWTN = TL Modifier + Population Modifier TL Modifier Table TL TL Modifier 0- 2 -0.5 3- 5 0 6- 8 0.5 9-11 1 12-13 1.5 Population Modifier Table PR Population Modifier 0 0 1 0.5 2 1 3 1.5 4 2 5 2.5 6 3 7 3.5 8 4 9 4.5 10 5 The simple way to remember the rule is that the population modifier is PR / 2. EX: World A has a TL of 8 and a PR of 9. That gives us a 0.5 + 4.5. World A has an UWTN of 5. 2. Determine Port Modifier Port Modifier Table Starport Class V IV III II I 0 UWTN 7+ 0 -1 -1.5 -2 -2.5 -5 6-6.5 0 -0.5 -1 -1.5 -2 -4.5 5-5.5 0 0 -0.5 -1 -1.5 -4 4-4.5 +0.5 0 0 -0.5 -1 -3.5 3-3.5 +0.5 +0.5 0 0 -0.5 -3 2-2.5 +1 +0.5 +0.5 0 0 -2.5 1-1.5 +1 +1 +0.5 +0.5 0 0 <1 +1.5 +1 +1 +0.5 +0.5 0 3. Determine World Trade Number WTN = UWTN + Port Modifier EX: World A has a Class III port. The means we deduct 0.5 from World A's UWTN to give it a WTN of 4.5. Now you are ready to find the Bilateral Trade Number for the worlds in question. 1. Determine the World Trade Classification Modifier (WTCM). One world is Ag and the other is either Ex or Na: +0.5 One world is In and the other is Ni: +0.5 Worlds are of differing Political Allegiance: -0.5 EX: World A with a WTN of 4.5 and World B with a WTN of 4. World A is Ag and Ni. World B is Na and In. Both are member worlds of the Third Imperium. We get the following numbers. 4.5 + 4 = 9.5. 9.5 + 0.5 + 0.5 (for the Ag/Na and In/Ni combinations) = 10.5. Note that if you have the case of a world being both Ex and Na you do *not* get a + 0.5 twice. This means that the maximum bonus to a pair of worlds is + 1. Client states are considered part of the government they are clients of for these calculations. Agricultural (Ag): Requires all of the following conditions to be met. Thin to Very Dense atmosphere (may be tainted), surface water between 35% and 84%, and PR between 5 and 7. Extreme Conditions (Ex): Any of the following. Diameter is < 500 miles. Atmosphere is Trace or less. Atmosphere is Super Dense or greater. Atmosphere is corrosive or exotic. If a world is As, De, Eo, Ic or Va is also Ex. Industrial (In): Requires both of the following conditions to be met. Trace or less atmosphere or tainted atmosphere to start. Also the world must have a PR of 9 or more. Non-Agricultural (Na): All of the following required. Very thin or less atmosphere. Surface water less than 35%. PR of 6 or more. Non-Industrial (Ni): PR of 6 or less. 2. Determine Distance Modifier. Count the hexes distance between the two worlds. Avoid Red zones. If possible, avoid Amber Zones and Class II or lower starports. Use the criteria in the section below on mapping to clarify the process of when you can and when you cannot avoid these worlds. The WTN Modifier is shown on the table below. Distance 0-1 0 2 -0.5 3-5 -1 6-9 -1.5 10-19 -2 20-29 -2.5 30-59 -3 60-99 -3.5 100-199 -4 200-299 -4.5 300-599 -5 600-999 -5.5 1,000+ -6 3. Calculate the Bilateral Trade Number (BTN). BTN = WTN1 + WTN2 + WTCM - Distance Modifier. The model breaks down when the difference in WTNs is extreme. The GM should feel free to reduce BTNs that seem excessive in such cases. There are some rules of thumb the GM can use to help in this decision. If the BTN is greater than [2*UWTN]+1 for the smaller world, the GM should probably reduce it. Alternately, if the trade route results in trade greater than 10 times the smaller worlds GWP, the GM should reduce it. EX: World A has a WTN of 6.5 and world B has 4.0. Plugging in the lower WTN will give us the following. [2*4]+1=9. Remember that you do the multiplication before the addition. These two worlds could support a Minor or Feeder route but not a Main, Major or Super route. That is only if the two worlds are either 0 or 1 hex apart. Further and the distance modifier will drop that down. Looking at the chart, the two worlds could support a Minor route if the distance is from 2 to 5 hexes. GWP is figured using the tables below with GWP equal to Base Per-Capita income * the planetary population. Base Per-Capita Income TL Income in Cr 13 24,400 12 15,000 11 9,375 10 5,860 9 3,660 8 2,290 7 1,430 6 895 5 560 4 350 3 220 2 135 1 85 0 55 Modifiers to Base Per-Capita Income Trade Class Rich *1.6 Industrial *1.4 Agricultural *1.2 Poor *0.8 Extreme *0.8 Non-Industrial *0.8 The above are cumulative. EX: World A has a TL of 9, a PR of 8 and is both Ag and Ni. If you do not have the actual population figure but only the PR, use a population that falls into the middle of the range. You can determine the middle of the range by adding the lower and the upper limits together and then dividing by 2. A PR of 9 gives a range of 1,000,000,000 to 9,999,999,999. Added together we get 10,999,999,999. Divide by 2 and we get 5,499,999,999.5 Looks like 5,500,000,000 is the median and it is what we will use. The base per-capita is 3,660 for the TL. When we modify it for the trade modifiers we get the following. 3,660 * 1.2 * 0.8 = 3,513.6. We then multiply the now figured per-capita income by the population. 3,513.6 * 5,500,000,000 = 19,324,800,000,000. The GWP for world A is 19,324,800,000,000. Some of the above Trade Classes were described earlier. Here are the new ones. Rich: All of the following must be met. Standard to Very Dense, non-tainted atmosphere. PR between 6 and 8. Moderate to high Control rating (2-5). Poor: Very Thin or Thin atmosphere and a surface water between 5% and 35%. BTN is shown in Cr trade per year. BTN 0 0-5 0.5 5-10 1 10-50 1.5 50-100 2 100-500 2.5 500-1,000 3 1,000-5,000 3.5 5,000-10,000 4 10,000-50,000 4.5 50,000-100,000 5 100,000-500,000 5.5 500,000-1,000,000 6 1,000,000-5,000,000 6.5 5,000,000-10,000,000 7 10,000,000-50,000,000 7.5 50,000,000-100,000,000 8 100,000,000-500,000,000 8.5 500,000,000-1,000,000,000 9 1,000,000,000-5,000,000,000 9.5 5,000,000,000-10,000,000,000 10 10,000,000,000-50,000,000,000 10.5 50,000,000,000-100,000,000,000 11 100,000,000,000-500,000,000,000 11.5 500,000,000,000-1,000,000,000,000 12+ 1,000,000,000,000+ Trade routes BTN 12 Super 11 Major 10 Main 9 Feeder 8 Minor Mapping trade routes. Creating trade route maps is both an art and a science. These guidelines are intended to make an otherwise confusing task more systematic and to make maps of the same place look as similar as possible when drawn by different people. Before drawing the map, you will need the complete economic statistics for your subsector. With these in hand, begin with the highest WTN world and draw all of the Super Routes for it. Then draw the Super Routes for the world with the next highest WTN and so on, until all Super Routes have been drawn in. Repeat this process for the Major Routes, once again starting with the highest WTN. Repeat this again for Main Routes, Feeder Routes and Minor Routes. This is also true if you are working on a full sector. Remember to have routes follow paths with J-2 or shorter legs, where possible. Jumps longer than two parsecs are only permitted along x-boat routes or when a route of at least Feeder magnitude can save a jump or more by using a jump-3 leg. The likelihood of a jump-3 leg existing increases when such a path can be used to avoid Class 2 or lesser starports, Amber zones, Red zones and worlds of different allegiance. Having other jump-3 routes in the vicinity helps as well, since ships can switch between them and manage capacity better. Avoid Red Zones. Avoid Amber Zones and Class II or worse ports where possible. If avoiding one would mean more legs than using an Amber Zone or poor port then do not avoid the offending world. Most Amber Zones are not a threat to trade traffic. The GM must use his own judgment on which Amber Zones are a true problem and which would be avoided. The reasons that ports of Class II or worse may be used is that when traffic is relatively low, say a Feeder or Minor route, those ships all have fuel scoops and fuel processing plants. Even the canonical 2,000 dton Frontier Transport from the Traveller Adventure had fuel scoops. These ships don't necessarily have to stop at the starport, they may be skimming at the gas giant or dipping in the oceans for their fuel and then moving on. These primitive worlds give good places for adventures to happen like fueling mishaps or pirate attacks and having trade routes pass through them gives people a reason to go there. For big trade routes, it makes a lot of sense for the big corporate shipping lines to operate their own private fueling stations in worlds without Class III+ starports. If you look at the cost of setting up a fueling station versus sending a whole bunch of megafreighters a week out of their way it's a no-brainer. This scenario too, can lead to good adventure possibilities. The world write-up of Boskone in Rim of Fire was inspired by the incongruity of a Super route passing through a virtually uninhabited asteroid system with a Class II port. As for why these refined fuel facilities don't show up in the starport class, it's because that represents the facilities at the SPA run official Imperial starport, and because these are *private* facilities not open to the public (another way the 'corps keep the independent trader down). Routes along x-boat lines may jump the full length of the x-boat link. Stick to jump three or less for other routes. Minor routes are limited to establishing J-2 or shorter legs. Minor routes may travel along and use the same legs as larger routes, even if they are longer than two parsecs. The reason to use jump-3 where possible is that the economics under GT ship design rules are such that a single jump-3 jump is almost the same per-parsec cost as a single jump-2 jump. So if you can make a single jump-3 jump instead of two jump-2 jumps, you save a ton of money. However, jump-3 ships are *not* as economical as jump-2 ships when they are forced to make 2 parsec jumps. Since they can't spread out their higher operating costs over more parsecs than a jump-2 ship, they cost considerably more per-parsec. That explains why the choice of using jump-3 legs in groups and jump-2 where needed. If three or more routes of a particular size pass on the same leg between two worlds, replace them with one route of the next size up. For instance, if three Feeder Routes pass between Collace and Mertactor, they should be replaced by one Main Route. This would likely be the result of traffic from several sets of trading partners on either side of Collace and Mertactor passing through these two worlds. While working down the route sizes, drop any additional routes when done with a class of route. If a leg has two main routes when you are done with all the main routes, disregard the additional main there. Also, once a leg has a class of route, you may ignore lower class routes there. EX: Between world A and world B you have a main route. While figuring the feeder routes you may ignore keeping track of them on that leg as it already has a higher route present. The above is a time saving shortcut for those that do not have some kind of program on the computer to do the work for them. If you do have a program then the better way is to keep track of all trade and choose the type of leg based on the total trade through each leg and compare on the BTN chart. If you are doing the work by hand take the shortcut. For those of you who have developed a program to do the labor I have a request. Share. Please. If a world has no routes, but has enough trade going through a particular neighbor to add up to a Minor Route, go ahead and give it one. If the background seems to suggest that a route is necessary where none exists, go ahead and add one. Conversely, if a route exists where the background suggests that a lesser route or no route should exist, it can be down-graded or eliminated. Use this freedom carefully, since it can quickly lead to arbitrary maps. Where there is the choice between two paths for a route, take the one with the most traffic already on it unless you can make the route larger by taking a shorter path. Determine if a shorter path yields a larger route by comparing the BTN of the route on both paths. If the shorter path has a higher BTN than the longer, established route, use the shorter path. EX: Planet A is 14 parsecs from Planet B. An established Feeder Route passes near to both. Using that path, the distance is 22 parsecs traveled and a BTN of 7.5. A shorter path is available that is 18 parsecs in distance but along which no traffic currently travels. That results in a BTN of 8. The amount of trade possible on the longer route is between fifty and one hundred million credits while along the shorter trade comes in between one hundred and five hundred million credits. Thus, trade along the shorter path makes economic sense even though it means moving off the established trade route path. The end result of this is you will probably have a single path of trade routes through a region but may have a short trade route nearby that serves a pair of worlds that have higher trade by charting a new path and avoiding the already existing trade path. Putting the data in a spreadsheet makes the entire task easier and much faster. With the appropriate formulas in place, a spreadsheet will present you with a list of only those worlds that are possible considering all the factors.