[pierreh]

While playing the city of Marlande lately I looked in detail at the intercity traffic, and the way it affects that city. Like Deramey where the intercity traffic is briefly described in the initial post of this CJ, and like Polsay, Marlande has pass-thru traffic: in its case, between Arcens and Desognes:


Let's look at the road traffic first. There is a highway link between Arcens and Desognes, with an interchange in Marlande for local purposes. In the following traffic volume view, 1 is the link with Arcens, 2 is the main exit ramp from the highway to the city's surface road network, 3 is the link with Desognes.



It corresponds to this city view:



The main highway, linking Arcens and Desognes, uses RHW-8S. The highway segments are clearly heavily used. We can look at some figures at key points on the highway network, starting with the link with Arcens:




Adding up the numbers we get 15'638 cars and 49'422 buses. This is clearly 'too much' for a RHW-8S network (although this raises the general question: 'how much is too much?').

How many Sims are travelling, by car and by bus, in pass-thru mode from Arcens to Desognes? Taking numbers at the highway interchange in the city we obtain the following:




Adding up the numbers we get 17'381 cars and 17'415 buses. Here is a first surprise: there are more cars in the interchange, than there are at the link with Arcens, although there are no ramps between those two points, where some cars could be added to the flow. I ascribe this to the fact that the respective numbers result from counts that are dynamically tallied during the running of the game, so that a 'photography' of a specific instant in time cannot yield perfectly coherent numbers. What matters most here are the orders of magnitude of the traffic flows.

On the branch of the highway that continues straight to the city, we see:



More surprising, there are 4051 cars on that branch, bringing the total number of cars in the interchange to 21'435, much in excess of what was measured at the link. On the other hand, there are 23'802 buses, yielding a total of 'only' 41'217 buses in the interchange: we 'lost' buses between the link and the interchange, even if there are no intermediate ramps on which the buses could get off the highway. Let's not dwell on those discrepancies in numbers. (The branch, a RHW-4S, is clearly underdimensioned, an issue to address at some point).

All that traffic, that is, the 4051 cars and the 23'802 buses, exits in the same ramp a bit further in the city. The ramp is underdimensioned for the purpose, the size of the traffic flow wasn't expected.



Most if not all Sims travelling on the buses change to subway lines at the RTMT bus+subway combo station (circled) next to the traffic circle on the right of the picture. (A similar situation can be observed in Arcens where those Sims board buses at a combo station - this will be documented later).

At the other side of the highway, where it links to Desognes, we measure the following flows:




Adding up the numbers gives 31'448 cars and 33'954 buses (plus trucks). There are close to twice as many cars as on the link to Arcens, and there are less buses. We can assume that, in addition to the thru traffic, there is a good level of car traffic originating in Marlande.

Again, this appears to be 'too much' traffic for the RHW-8S.


Placing a subway link to reduce the load on buses hasn't been as successful sofar, as it is in the case of the direct traffic between Arcens and Cherenne, illustrated in my previous post. The situation is as follows:



The subway coming from Arcens (bottom right, 1) connects to another subway tube in a GLR+subway combo on the upper right of the picture (2); that second tube, with 2 further stations, links to Desognes on the upper left of the picture (3). There are GLR tracks connecting to the stations, that take traffic away from the subway lines.

Traffic is measured in the subway links: in the link to Arcens:



In the link to Desognes:



The flows appear rather balanced, but it would be very difficult to distinguish between thru traffic and traffic originating or terminating locally in Marlande.


There is also a direct rail link between Arcens and Desognes, bypassing the main railway station in Marlande. The link with Arcens does not see a high usage:



The link with Desognes, with dual pairs of tracks, has a higher usage:




The total usage here is 53'786. But if we look at the bypass tracks we see a rather low number of pass-thru train passengers (7473):



It appears that the bulk of train riders measured at the link with Marlande are boarding the trains at the main train station in Marlande. The usage of rail for pass-thru traffic is negligible.


There is a need to improve on the current traffic situation in Marlande. A widening of the main highway from RHW-8S to RHW-10S is possible (although the gain in performance is rather small) and a few branches and ramps should be upgraded. At the same time, the excessive usage of buses needs to be reduced. The subway layouts in the 3 cities involved will be reviewed, with the intent to increase the usage of the subway for intercity traffic. More about this, then, later...