The rules say that arty units pay double for off-road movement. How is that applied?
Is it only for the cost to enter the hex and not to cross the hexside?
Or: Is it for both the hexside and hex cost.
The latter case means that an arty unit of 8 ma could never move onto Little Round Top, which they did historically.
The cost to move 1 hex onto LRT in the best case would be: +3 for hill and 2 for the hex for a total of 5 ma points x2 for arty off-road movement, a total cost of 10, which is 2 more than its ma.
Harry van der Werff
Rules 3.24 Artillery: “Artillery have Move 8, but off-road moves cost double.”
Rules 3.25 Horse Artillery: “They function like artillery, except they have Move 10…”
This query involves (regular) artillery as mentioned in rule 3.24 while moving off-road, i.e. in line.
1. ARTILLERY MP COSTS
Every hexside crossed expends at least 2 MP’s (= base move) irrelevant of hex terrain. Crossing a hexside that features certain terrain may in addition to the base move costs, increase the movement costs depending on the nature of the hexside terrain. Crossing a hexside that contains other terrain than CLEAR expends the sum of their (terrain) respective MPs. Terrain movement costs are cumulative.
When calculating the total movement costs (Move) first consider the base move, then add the additional move costs due to terrain and then double this outcome(base + terrain) for artillery.
To answer the question: yes, units consider both the base costs and the hexside costs for movement; these costs are then doubled for artillery.
2. ARTILLERY ON LITTLE ROUND TOP (HEX R7)
Regular artillery can only move into FRIENDLY or NEUTRAL hexes.
The elevation of a hill is ; the hexside terrain may contain one (1) or two (2) ridges (slopes) in addition to possible other hexside terrain.
When entering hex R7(destination) from hex S8 (departure) the total movement costs for a regular artillery are 8: 2 MPs base + 1 MP ridge + 1 MP woods x 2. Hex S8 has an elevation of  which means that previously somewhere in the journey towards hex S8 a ridge has been crossed. Entering hex R7 from any other adjacent hex than hex S8 would exceed the movement allowance (maximum movement points) of a regular artillery unit.
Still, in disregard of the movement allowance, regular artillery can enter into hex R7 from any adjacent hex provided hex R7 is FRIENDLY or NEUTRAL. According to rule 6.4 a unit can always move one (1) hex regardless of terrain.
To answer the question: yes, artillery can enter Little Round Top (hex R7).
Relevant rules & information (Rules Version 1.2)
Page 1: 1.2 Move Phase
Page 2: 2.2 Terrain
Page 2: 2.2 Little Round Top
Page 2: 2.2 Slopes
Page 2: 2.3 Elevation
Page 2: sidebar Hex vs Hexside Terrain
Page 3: 3.24 Artillery
Page 3: 3.25 Horse Artillery
Page 6: 6.1 Move
Page 6: 6.3 Movement Points (MP)
Page 6: 6.4 Terrain & Movement
Page 6: 6.5 Road Movement
Page 6: 6.61 Zones of Control (ZOCs)
Page 6: 6.62 Frontline Hexes
Page 6: sidebar Movement Examples
Page 6: sidebar COLUMN & LINE (Optional)
Page 12: tables UNIT DATA & TERRAIN EFFECTS
(And thanks again.)m