the idea of alternative destinations and having a higher proportion of passengers using local transport was intended to have that effect
I think this is in essence realistic and a nice feature, but wouldn't try to use it as major weapon against a larger network. The definition of "local" to a passenger is usually based on travel time as per the isochrones in one of AEO's links, rather than drawing a circle around one's current location - can't recall whether your "localisation" model is based on distance or travel time.
This would, of course, be in addition to the per month maintenance costs, as there are some tasks that need doing no matter how much or little that a way is used. One interesting consequence of this is in relation to canals, which, presumably, would have a zero per tonne maintenance cost, as canals do not wear out, as such, although they do need regular de-silting and weed-killing along the towpaths, etc.. This would, I suppose, add to canals' existing dynamic as being very expensive to build but very cheap to maintain compared to other types of way. How much of a difference would this particular item have to the overall dynamic of the exponential increase in profitability that you describe above, do you think?
A canal, like any other way, only needs to be maintained in usable condition if it is being used. It can silt up all it wants otherwise. If canals had a high fixed maintenance cost regardless of use then they all would have been filled in when the railways came. With most ways there are tasks that need doing even if it's not in use, but their cost is negligible compared with maintaining them in use. For the sim, any cost that is shifted from fixed to variable will help balance the challenges of early and mature gameplay, and importantly provides a simple mechanism to balance them. So if implementing only one way maintenance cost calculation, make it variable. The only role of a fixed cost for way maintenance in the sim is to discourage over-building, and to encourage the player to bulldoze anything they think they no longer need. So the question for implementing fixed maintenance cost is: do we want to force the player to bulldoze every canal/road/rail tile they no longer need? If that's not important, don't bother including a fixed cost.
EDIT: sorry, slightly misinterpreted what you wrote. The only way I can see of capturing that cost otherwise is if there's a way of determining which tiles are part of existing lines, and charging fixed maintenance costs to those tiles only.
Another question is what one does about airport runways; presumably, they are also more expensive to maintain the higher the tonnage of aircraft that use them in any given period?
Yes, they will deteriorate faster. Runways, like roads, rails, and bridges, are built to loading specifications. Many had to be widened to accommodate the A380, for example. Yes, they will become more expensive to maintain, but of course this will not impact significantly on the overall cost of air operations. The dynamics of the air industry are quite different, and most sensitive to fuel costs, which aren't explicit in the sim. The cost of real estate and ground infrastructure are comparatively less significant.
One neat way of doing that in Simutrans would be to use the existing feature of headquarters
Cute, but sounds really messy and arbitrary, and complicates gameplay, especially for newbies, who have enough to get their heads around as it is. Would be simpler to charge an admin cost on all vehicles/infrastructure, but of course this would be a linear cost in relation to network size.
The problem with the approach of requiring that vehicles be replaced at a certain point in their lifecycle is somewhat arbitrary, as, in reality, transport operators would have the choice to keep them going at higher cost or invest the capital (if they can afford it) in new equipment. What you describe as the simple approach gives rise to arbitrary outcomes.
Granted, but this is much more realistic than no lifespan, and I as a player would find it more acceptable than having to micro-manage replacement decisions. It's also very simple to understand. I'm not talking about replacing them at a certain point of their life-cycle, but at the end of it - their kilometres are up. This is not the same as manufacturing obsolescence, will get to that in a minute.
There is also this to consider: suppose that a vehicle costs 10c/km to maintain. After 100,000 km, it requires an overhaul costing 100,000c. That could be simulated by, as you suggest, making the player pay 100,000c all of a sudden after 100,000km of use. But is not requiring an overhaul after a fixed amount of time not equivalent to the vehicle having a higher maintenance cost; in other words, can one not simply amortise the cost of all major overhauls during the vehicle's natural lifecycle into its per kilometre maintenance cost, so that, in the above example, the maintenance cost is 11c/km rather than 10c/km?
Good example, and one that strikes at the heart of the early vs mature game issue. Paying for the overhaul after 100,000km, as would happen in the real world, gives the player the opportunity to raise the money to pay for it. to make the vehicle pay for itself. Asking the player to put money aside from Day 1 for an overhaul that's years in the future cripples early gameplay. If the player fails to make the vehicle pay for its overhaul in 100,000km of use, that's the player's fault. We'll get better gameplay if maintenance in year 1 costs, say, 3c/km, and creeps up year on year, after the player's been able to make some money out of the equipment first.
The purpose of the current obsolescence increase is to reflect the increase of cost after a vehicle's normal lifecycle has expired
Obsolescence and unit lifecycle are totally different concepts. Think of them completely separately. Obsolescence means the manufacturer no longer makes it (although spare parts usually remain in production for some time), Lifecycle means the period over which something is economic to own and operate. Something that's obsolete may still be fit-for-purpose and economic to use - most of the vehicles you see on land and sea are obsolete. If you have an IT background you may be used to thinking of obsolete as being equivalent to "inadequate and uneconomic", but with transport infrastructure and equipment things don't (can't) change that quickly. Obsolescence usually only impacts on lifecycle when parts become expensive and/or difficult to obtain, which is typically many years or decades after the unit became "obsolete". To say "I can operate a vehicle for peanuts for decades longer than a real one would last, until the manufacturer stops making new ones, then I can't afford to run it" is a long way from reality, and misses an opportunity to challenge mature gameplay with the simple but intuitive concept that "the more I use it, the faster it wears out".
Is there a particular reason for having all vehicles having the same lifecycle cost? I don't think that this was how things panned out in reality, was it; some vehicles had a far higher life-cycle cost than others. I'd rather simulate that reality if possible, and I don't see any particular reason why it's not possible.
It's certainly possible, but I don't believe it's desirable. This is a fundamental philosophical issue for historical sims - do you model things as they actually panned out, or as people at the time thought they would pan out? We might know now that loco x built in 1926 was a lemon, it ended up costing its owners three times as much to maintain as its competitor loco y. But did the sucker buying loco x in 1926 know that? Would anyone have bought loco x in hindsight? Would it even have been made? Half the joy of playing historical sims is to make decisions as if one was there at the time, with the information known at the time. If loco x is given parameters that make it uneconomic, because in the real world it turned out to be uneconomic, then one of the game rules becomes "never buy loco x, you'll go broke". Is that desirable?
In practice there was/remains uncertainty in every equipment purchase, uncertainty that's not modelled in Simutrans - you buy something and it performs exactly as the manufacturer said it would.
The goal, as I understand it, is to offer a range of vehicles with performance that's sufficiently differential to make some items more suitable for some purposes than others, but not so differential that some of those vehicles are practically useless (for economic or technical reasons). It also strangles gameplay a bit if there's only ever one choice for any given application; for one we won't get to see the full variety of trains that have been made for the sim. You are trying to obtain and use all historical numbers, but if they don't produce the right gameplay you'll have to change them anyway. I can see that Simutrans is an outlet for your love of rail history but I suggest drawing a boundary between total historical accuracy and gameplay here

There's also a catch here with the current obsolescence model - we might know now that loco y was manufactured from 1919 to 1936, but did anyone buying the loco in 1924 know what the obsolescence date would be? In practice it didn't matter, since, as explained above, the working life of the loco had little to do with the cessation of manufacture of new ones, but the way the sim is set up the obsolescence date is critical, and historically would not have been known in advance. The same applies to technological advance - we might know now that technology z arrived in 1906 and greatly reduced operating costs of new locos, so in 1903 we might need new locos but hold off on purchasing because we know what's coming up. Would a real-world operator in 1903 have had the same knowledge?
I am reliably informed by somebody who works in transport that there are many things on vehicles (rubber seals are apparently one example) that need maintaining just as much if a vehicle is sitting idle as if it is being used.
True. Now ask them how much those things cost compared to the costs associated with usage (if they work on the shop floor they probably won't know any more than how many hours it sits in the shop, usually only the accountants and managers know the costs). When it's in use it's probably getting a major engine service and a brake system overhaul on the same frequency as the rubber seal replacement. It's not the number of things, it's the cost of them. As I said last post, the dynamic and incentives of the fixed ownership costs are already captured by attaching a cost to money, so maintaining an additional parameter is just extra work.
Would there be merit in adding a credit interest rate to the player's bank account balance, too?
I vote yes. Makes the player think more about the time value of money and stengthens dynamics like the one above.
How much effect do you think that the per hour cost would have in a Simutrans environment? That one would be harder to implement than some of the other suggestions mentioned above, and so would require some careful thought.
I'll answer that with a question. You've seen what congestion can do to $/km - how much effect would it have if operating costs were increased by 25%? Or 50%? Or 100%? This is what will happen to any player who fails to manage congestion adequately. The beauty of it is that it has about zero impact early game, when there's near zero congestion, but kicks in when lines get busier. It's a dynamic that increases in impact with, and in direct opposition to, capital utilisation, so it's a great balancer in a mature game. It's also a really simple mathematical concept (can be explained as being a bit like a taxi meter, which most of us are familiar with) that has powerful and non-linear effects.
I had assumed this would be really easy to compute, as I thought Experimental was already tracking journey times to calculate the revenue for each trip. At the end of each journey (all journeys: loaded, empty, or depot) the journey time is multiplied by the hourly cost of every unit in the convoy, and billed to operating costs. Is it not this simple? Waiting time would ideally be included but it's not critical.
I also notice that you include debt servicing cost, which, in Simutrans, of course, should not be bundled up with the vehicle costs, as a player may well not be in debt at all (indeed, usually is not).
I included it because there are costs associated with money - interest, and opportunity cost - that have a bearing on a player's decision-making. It is not to be included in the cost of the unit, but rather to calculate its life-cycle cost so as to balance the costs between units. If two vehicles cost the same total number of dollars over their lives, but one has higher purchase price in exchange for lower operating costs, then their true life-cycle costs are not the same when the time value of money is taken into account. Real-world purchasing decisions are driven by NPV analyses that consider not just the number of dollars, but when those dollars need to be spent, because deferring expenditure either reduces interest costs or frees up cash to take other profit-making opportunities (the latter being a big issue in the early game, hence one always goes with low purchase prices to maximise the amount of equipment one can buy). If I buy the loco with the higher purchase price, that price needs to reflect the fact that I've forgone interest or opportunity in the present. In practice this means that to be economic, the more expensive loco needs to be cheaper than it would be if the expenditure was calculated without respect for timing. If we build relative pricing without considering this then the lower purchase price, higher operating cost locos will have an unintended cost advantage.
You can explore this dynamic with the comparison spreadsheet:
1. Set the interest rate to zero.
2. Configure vehicles 1 & 2 with identical parameters, except vehicle 2 has lower operating costs. Adjust the purchase price of vehicle 2 so the lifecycle costs come out equal. Copy vehicle 2's parameters to vehicle 3 for reference.
3. Now introduce an interest rate. Both lifecycle costs increase, but vehicle 2's has increased by more. Vehicle 2's purchase price needs to be reduced for the lifecycle costs to come out equal.
So what I'm proposing is that this dynamic is factored into calculating the purchase prices for the pakset. In the spreadsheet purchase price is an input, but what I'm saying is that it is meant to be an output. This spreadsheet was built for demonstration purposes; to price the pakset I would specify the lifecycle unit cost as an input, being roughly the same for all units. Then either purchase or operating cost would be an input, and the other would be the output.
Of course, this is of limited use if vehicles don't have a realistic lifecycle, as they currently don't. In Standard it's infinite, while in Ex it's arbitrary, being the number of years until manufacturing obsolescence rather than the amount of work done until it wears out. The whole idea of balancing purchase and operating costs is dependent on things having a finite
operating life, so if this isn't built into the sim in a realistic manner, those parameters won't produce realistic outcomes so there's no need to worry about them too much.
Sounds to me like the speedbonus can capture technological progress pretty well, so that should be enough. As far as I can see it also means that it's not necessary to make later, higher performing units more expensive than earlier ones.