Introduction
David G. D. Hecht's 18EU game is thoroughly enjoyable as designed.  After a few playings, however, one realizes that the northwest region of the board tends to be the most profitable, while the south is something of a backwater.  The high (M) mountains are a major reason for this, for at they are too costly (at £120 per hex) to be crossed except occasionally at their western end (Frejus, Lötschberg, and perhaps Simplon).  Sometimes they may not be crossed at all.  Game strategies are accordingly determined with no serious expectation of any north-south crossings of the Alps occurring between  Basel and Vienna, where an extra hex of £60 rough terrain must also be crossed in addition to the £120 cost for the high mountains.

Historically, however, the Alps were crossed in numerous places to facilitate trade between northern Italy and its neighbors to the north. This led me to consider several variant notions in order to provide incentive for players to lay track across the Alps.  In the end I settled on a small group of variant rules and play-tested them.  After two very successful games using these rules, I now offer them to the 18xx community at large for both comments and further play-testing by those so inclined to give them a try.  I have found that this variant lasts about as long as the normal game length for 18EU, which in my circle typically lasts for six pairs of ORs.

Rules for the Alpine Variant
1. Modification to Rule 4.2.1 - Minor Company Initial Sale Round: The amount paid in order to take possession of a Minor Company is placed in the Minor Company's treasury, rather than the bank,

2. Modification to Rule 4.4.1 - Lay or Upgrade Track: The placement of each and every tile incurs construction costs as shown below:
Open, clear hex
£30 per yellow tile; £10 per any upgrade/tile promotion

Rough hex 
£60 per yellow tile; £10 per any upgrade/tile promotion

3. Modification to rule 4.4.3 - Train Operation and Earnings Calculation:
When calculating the revenue for a train whose route crosses a Mountain (£120) hex, the train gains an additional Alpine Bonus of £10 per City or Red Off-Map Location that is included in that train's run.   To gain this Alpine Bonus, the train must run to at least one City or Red Off-Map Location on each side of the mountain.  Towns and Ports are not eligible for these bonuses, although they still earn their normal revenue amounts for the train's run.

If the same train crosses a mountain hex more than once, add an extra £10 per additional Mountain (£120) hex crossed.  This extra £10 bonus is not received when the route merely runs along the "spine" of a mountain without crossing to a City or Red Off-Map Location.

Example #1:  A route that ran from Strasbourg via the Lötschberg Pass to Milan, Genoa and Turin would gain an additional Alpine Bonus of £40 over its normal revenue amount.  If the train from Strasbourg ran the same route but extended it beyond Turin through the Frejus Mountain to Lyon it would gain a total bonus of £50 for the five cities, plus £10 more because it had crossed the Mountains twice.  (It would have crossed at Lötschberg and then again at Frejus.)

Example #2: A Route that ran from Trieste via the Brenner pass to Munich and then recrossed the Mountains at Albula to continue to Rome would gain a total Alpine Bonus of £30 for Trieste, Munich and Rome, plus £10 more for having crossed the Mountains twice in one run.  If the train had instead run from Trieste to the Brenner Mountain Pass and then directly to the Albula Mountain Pass before continuing on to Rome via Bologna, it would have gained a bonus of only £20 (£10 each for Trieste and for Rome) since it merely ran along the spine of the mountain without crossing to another City in between, such as Munich.

Salzburg Special Rule: Any route that connects Vienna to Salzburg and from there continues to Munich, Strasbourg, or Frankfort, shall be considered eligible for the Alpine Bonus.  Since a route through the two Rough hexes of M10 (northwest of Vienna) and N9 (Salzburg) would cost a total of £120 to build, such a route is to be considered equivalent to a Mountain crossing.  [Note that this special case is included because otherwise there is little reason to ever build track to Salzburg.]

Notes on 18EU Strategy with these Alpine Variant Rules 
Minors #5 and #10 become much more significant in this variant, since they are in excellent positions to cooperate with and link up with another Minor north of the mountains.  The bidding for these companies should become more active, along with that for Minors # 13, #14, and #15 which will also tend to be valued more highly, since they are most likely to provide the route for the track connections that bridge the high mountains from the north and west.   Even Minors #11 or #6 may make attempts to reach Salzburg and beyond to gain the Alpine bonus.  The income from these trans-Alpine routes should compete favorably with the revenue from those companies that are dominant in the northwestern portion of the map.

Design Note
All hexes were given construction costs in order to level the playing field a bit.  The mountain and rough terrain costs are quite high in the regular game, but having to pay £30 for each clear hex now makes for comparatively less of a burden on those who wish to climb the mountains.  In fact, it makes a shorter, direct route more appealing since the route through the mountain should also eventually provide bonus revenues.  So that early in the game the Minors can commence building  track, especially Alpine routes, they now begin with cash in hand according to what was paid for them by the player who bought them.  The Alpine routes are obviously more valuable the longer they are in play, so this is a useful feature.  By the time the 8-trains appear, this could mean an extra £80 per turn in revenues for a company using an Alpine route.  The northwest won't tend to dominate the game as it does in the original rules.