Let's define Travellers as "anyone directly involved in interstellar affairs," and estimate the total population of Travellers in the Third Imperium, c. 1120. I get six billion, out of a total Imperial population of 10.4 trillion, or around one in 1,800. The population under Imperial jurisdiction at any given time will be much smaller, of course. Details follow below. For the purpose of this discussion, I will use the existing online sector data as summarized by Anthony Jackson: http://maps.travellercentral.com/imperial_summary.html Trade and other figures are based on GURPS Traveller, specifically GT: Far Trader, Starports, and Ground Forces. Military forces in particular were estimated according to the process outlined at: http://www.io.com/~thrash/milforce.html Here I have, however, factored in a population modifier of 3 across the board, in accordance with Anthony's model.
Per Anthony's figures, the total annual trade in the Imperium is approximately TCr2,500, or about 125 billion dtons. Freighters are around 50% cargo and average 35 jumps per year at 65-95% fill, so this requires 7.5-11 billion dtons of shipping. Passengers are in addition to freight traffic, not in lieu of it: TCr2,500 per year means 8 billion passengers, or 160 million per week. Passengers require 10 dtons of ship each (1); at 65-95% fill this requires an additional 1.7-2.4 billion dtons. The total is 9.2-13.4 billion dtons of shipping. Merchant ships require one crewman per 100 dtons (up to one per 40 dtons on smaller vessels): 100-150 million personnel serving on shipboard. There will generally be two personnel ashore for every one on shipboard (2): 200-300 million. Imperial starports (per GT: Starports, p. 65) employ another 30 million (3), for a total Merchant population of 330-480 million; with dependents, this is 0.5-1.9 billion -- say, one billion.
There should be about 2,500-2,600 Scout bases in the Imperium, 1800- 2000 xboat stations, and 320 way stations. Per GT: Starports, p. 68, that puts the Scout population at about 1 million, plus 6.2 million other civilian employees and 12.8 million family members: 20 million total.
There are three navies in classic Traveller: planetary, subsector/ colonial, and Imperial. I will neglect the planetary navies (as being undeniably local forces), and concentrate on colonial and Imperial strengths. Fifth Frontier War and Fighting Ships together imply that each subsector has a colonial fleet of 8.1-75 million dtons (including escorts); the Imperial Navy is 7.2-31 million dtons per subsector (4). Assuming one naval crewman per 20 dtons of combatant, one per 40 dtons of escort, and one ashore for every one aboard gives roughly 1.0-8.4 million per subsector, or 220 million to 1.9 billion for the Imperium as a whole; I'll figure Marines are included in this number. Civilian employees (110-950 million, per pp. T:SP66-67) and dependents (500 million to 4.3 billion, ditto) add up to 610 million to 5.2 billion navy-related civilians. I'll say two billion total naval Travellers.
There are also three categories of army troops: planetary defense forces, colonial expeditionary troops, and Imperial regulars. Again I will neglect planetary forces in favor of colonial and Imperial troops. Based on Fifth Frontier War, each subsector can field approximately 6,000 battalion-equivalents of colonial troops, or perhaps 3 million soldiers. The Imperial army is somewhat harder to define, but appears to field about 10% this many troops (600 BE, or 300,000 soldiers) per subsector. If the Imperial Army base establishment uses one soldier to support one soldier in the field (a standard ratio), then the total Imperial Army strength is perhaps 95 million (5). Expeditionary colonial forces amount to another 470 million (their base establishment is included with planetary forces, and ignored). Counting civilians and dependants is harder. Assuming similar ratios for Imperial army and navy civilians, and neglecting colonial civilians completely, gives 50 million civilians and 225 million dependants. Total Army population is 840 million.
The total population of "other" Travellers -- entertainers, scientists, rogues, diplomats, etc. -- is difficult to estimate. I will take the passenger figures from the Merchant section, and assume that all Travellers will travel at least one week a year. That puts the Other population between 160 million and 8 billion; call it one billion, as a moderate value. With dependents, this is probably two billion total.
Merchant 1,000 million Scout 20 million Navy/Marine 2,000 million Army 840 million Other 2,000 million Total 5,860 million Of these, maybe half are under Imperial civil jurisdiction at any given time. This population represents less than one in 1,800 Imperial residents, or about 0.056%. These numbers are necessarily rough. Just within the estimates given, the total could vary from 2.3 to 17.9 billion, and not everyone will agree with my assumptions. Take them for what they're worth.
(1) Assuming a 1:2:3 ratio of high:mid:low passengers, based on 1901-1950 steamship statistics, and taking both baggage and extra crew requirements into account. (2) These are all full-time Merchants: admin staff, support staff, brokers, factors, shore duty, training, hospital, leave, transfers, ships in rebuild, etc. The figure is a real-world rule of thumb for both the shipping industry and naval forces; it is also reflected in the extended character generation systems in Books 5 and 7. Dependents are counted separately, the factor depending on whether you believe most couples will be dual-service or not. (3) Note that p. T:SP65 implies that only about 20% of a starport's budget is spent at the starport: there is one employee for every KCr200, but assuming a productivity 2.7x average each one produces only KCr40 per year. The other 80% goes to the planetary economy, but I will ignore those workers as being only indirectly involved. (4) MT (and later versions, apparently) assume that the Imperial Navy is roughly equal to the "reserve" (i.e., colonial) fleet. This increases the total naval population to 1.1-8.8 billion -- call it 2.7 billion. (5) This also accords with the formula in GT: Ground Forces, as best I can tell, if population modifiers are included. Copyright (c) 2006 by Christopher B. Thrash
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