Economic impact of private cars

[jamespetts]

As might be apparent from some of my recent posts and patches, I am looking for ways to make Simutrans more challenging in the later stages of a game, when players have succeeded in building a large and profitable transportation network. One of the key elements of maintaining the challenge is to require players continually to adapt and modify their networks to keep up with changing circumstances. The timeline option with varying speed bonuses goes some way towards doing that by requiring players to upgrade vehicles periodically, but a network with a high level of demand and a transportation company with overflowing money can do that with ease.

One aspect of transportation that is not simulated in the timeline option of Simutrans (at least, as far as I can discern) is the rise of the private car. I know that there is some degree of simulation of city cars, which does depend on the era, but, from what I understand of the code, city cars seem to be treated by the virtual passengers as a mode of transport of last resort, and do not, therefore, present any degree of competition to 'busses and trains. In real life, from about the 1950s onwards, the private car vastly diminished demand for public transport for short and medium distance journeys, while air travel became increasingly popular for long-distance journeys, the combined effect of which was a great reduction in the size of railway networks in the developed world as demand shrank. Counterbalanced against that, in areas and at times where traffic congestion has been high, demand for public transport (especially rail transport) has been strong, with the result that, in the UK, the closures of railway lines that would in the 1960s have been most unprofitable are now greatly lamented, since those lines would be in strong demand to-day. A few routes that have been closed for decades are being re-opened, and still more are being considered because of a great rise in traffic congestion in past decades.

This aspect of transport history could add a very interesting dimension to Simutrans, and make the challenges for the player in later stages of the game far more interesting. A timeline of percentage of private car ownership could be set up in a file similar to speedbonus.tab in layout. Then, for all passenger journeys, the computer would first allocate some generated passengers as car owners (randomly, but the degree of probability being based on the percentage of car ownership identified in the privatecar.tab file), and, for those passengers, decide whether or not their journey would be by private car rather than by public transport, taking into account the length of the journey (journeys over a certain length being less likely to be car journeys), the congestion in the origin and destination cities (deduced heuristically, perhaps simply from the number of generated cars last month divided by the number of city road tiles in the city), the quality of public transport service in the origin city (the same as is taken into account when deciding whether a city will grow), whether or not there is a road connexion between the origin and destination cities (if not, the car option would be discarded entirely), and a random preference factor (weighted in accordance with a value set in simuconf.tab).

I have noticed in the code that there is provision for "city cars with destinations", albeit only compiled conditionally. I am not sure exactly how this system works, but it might be the sort of thing that could easily link into the above suggestion.

To make this work properly, during the game, it would greatly help if the public service player was effectively given an AI, and slowly constructed roads connecting all cities to each other over the course of decades, the speed of construction depending on the percentage of private car ownerships. The alternative would be simply to start with all towns connected to each other by road, which is realistic in any event (and probably a great deal easier to code).

If an "advanced" mode was implemented, as discussed here, then this would be a good candidate for a feature activated only in that mode. Also, a similar idea in respect of freight could be implemented, whereby, according to a pre-set timeline, certain sorts of industries decline during the course of the game, with factories closing, whilst other industries grow and prosper (and perhaps later decline themselves). Indeed, there might even be a macroeconomic factor of overall amounts of industry increasing and decreasing as time passes, either semi-randomly, or according to a pre-set timeline. All of that would greatly increase the challenge in the later parts of the game, requiring new networks to be created, whilst older networks would have to close (and possibly then be re-opened later).

[Fabio]

I support every proposal to make the private cars more than "eyecandy" or "snag in gameplay because they cause traffic jams"...

[prissi]

The citycars with destinations create citycars with a very simple wayfinder: at each crossing they choose with 80% (or so) probability the way closer to destination. This destination is a "no route" from passenger creation. When it reaches within 20 tiles of the destination, it will self destruct. Thus you need to cover the whole country with a road network, even if you play trains only. And still too many citycars got lost in towns, thus I never included it into the releases.

However, testing for road connection before creating citycars is completely unrealistic, given the time needed for this.

[jamespetts]

Prissi,

thank you for your most useful reply :-) The difficulty, then, would be the computational cost of testing for connexions in advance? Hmm - would it be possible, for example, to test whether there is any road connexion between each pair of towns periodically, and use a table of data for the purpose of setting the citycars' destinations?

Edit: The other alternative, of course, would be not to test at all, and have the game assume that there is some "private transport" way of getting between any origin and any destination if only the Simu-citizens have the wherewithal to take advantage of it (set in the privatecars.tab file). That would have broadly the same economic impact, be easier to code, and would create less computational overhead (citycars with destinations still ought be created, however, for the congestion parameter to be taken into account).

[colonyan]

This is another curious topic!

Road: I would say all cities should be connected with most basic road with any new map(unless specifically avoided).
        Nation wide road network existed any civilized nation unless it is in the middle of huge Sahara.
        The concern is that it takes load time to generate those road depending on the number of cities....     

        Also, Jame's idea of public player slowly adding road connection is interesting and I'm with that.