+3 for every 5 consecutive interstate cities
means 15 bonuses for i-80, 3 bonuses for i-55 and so on. roughly 100 interstate bonuses is a figure that is by no means impossible or even especially difficult to code, but it'll be a lengthy and tedious process with a lot of copying where errors are hard to spot, unless someone knows of a shortcut; by shortcut, i mean something more elegant than the brute force method of copying the list of ordered i-80 cities 14 times, then deleting the unwanted ones from each bonus. +3 for every 5 interstate cities
is so easy that both players in 1v1 are almost certain to start with one or more of these bonuses, with the first player depriving the second player of one or more of his bonuses, which is not what we want. another downside is that, on the longer interstates such as i-80, the principles of best play dictate that a player has to keep counting the number of an opponent's cities on that road to determine how many cities he must conquer to reduce that opponent's current interstate bonus, which is not much fun. the upside is that the new collections xml makes implementing this bonus a piece of cake.
is +5 for every 7 consecutive interstate cities
a reasonable alternative? this reduces the number of interstate bonuses by 28. will players bother with playing for such a long, thin bonus that can be broken at almost every city? if not, then this defeats the point of the bonus.