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How's called the inverted lane in your country?

Started by An_dz, December 01, 2012, 10:43:16 PM

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I really wonder about the road sign examples. 3 out of those five seems at situation where there is nearly no advantage to left hand driving, at least compared to the wicked traffic construct earlier in Canada or Barcelona.


@An_dz:  OMG!  Those signs seem too small for me...  They'd have to have more colors, big letters and flashing lights...  Aren't there accidents in those roads?  What happens if I go to a party in one such street, and after a few hours, I leave the house and forget about the sign?

I imagine those streets are very short...


Generally short and road sometimes have different ground paint. Generally with those light reflector on road axis all the road or with a large yellow paint on axis, like paint on middle bottom of this image. But not that large, probably 70-100cm.


Quote from: An_dz on December 06, 2012, 02:59:26 PM
like paint on middle bottom of this image.
That's not paint – it's dirt... normally (after rain / cleaning) it's actually white.


I know of several places in the UK (Bath comes to mind immediately) where driving is on the right, but that is due to the effect of perverse one-way systems.

And the less said of the Magic Roundabout in Swindon, the better. (Hands up who's tried it in RL - keep your hands up if you didn't hit something.) :)

Edit: Still keep you hands up if upon exiting, you didn't find the nearest lay-by and start sobbing. :)
For Non-UK residents gives you an idea. But no amount of reading about it will compare to actually trying it out.


Haven't seen the Swindon one in real life but I have cycled around the Hemel Hempstead version!


The problem with magic roundabouts is more the intimidation value. It's like the old principle that the safer a person feels behind a wheel, the higher the death rate. Imagine - if I put an 18 inch long 2 inch wide serrated steel spike in the middle of your steering wheel so that it was pointing right at your face or heart - you'd drive REALLY carefully. But not with our airbags, roll-bars et al then a certain recklessness builds in. There is some evidence that magic roundabouts actually cut serious accidents as everyone is too intimidated to take risks. The 'old habit' of shooting along at 45mph, taking the inside track (without a moment's thought) and scooting off on the opposite side of the roundabout cannot occur.

In real-life magic roundabouts (as you've almost certainly experienced in Hemel Hempstead - it is almost identical in layout) it is easy for a real person to be distracted by the vast amount of data you must use at once though - so it pushes up the 'simple accident' rate. And it's bloody scary. In ST however, the AI system is harder to fool.

Since posting that entry last night I actually had a deep thought. Can a magic roundabout be built in ST? And if so, is it better than a basic roundabout in some situations?

I've made a few test models so far on a new map and what it appears is that it spreads the traffic across multiple routes. The reason this works is the system has 5 entrances each feeding the other four exits for a total of 20 combinations. The routing system you would use in RL to negotiate the system is identical to how ST works it out. (I.e. if you are going from the first to the fourth exit you would use a specific set of roundabouts and in that order in both RL and ST.) And each of these 20 combinations is unique and utilises the entire network between them. And you don't need complex waypoint structures in the schedule to make sure it follows the right route - it is set up by using one-way signs which then apply to all vehicles - including NPC citycars and opponents. In a normal roundabout of the same overall dimensions (it takes a space of about 20 tiles in diameter to replicate) you get all forms of jams due to there being too few intersections.

When running road routes it is all too easy to get too much traffic trying to jam down a single route even though you might have built a 'relief road' for some parts of it. (A relief road that never gets used as the routing disregards it).

Another way of looking at a magic roundabout is to view a motorway/highway interchange from the air. (Say spaghetti junction or the M4/M5 interchange near Bristol*). Look down on it and every 'in-route' can get access to every 'out-route'. On motorways and highways they need bridges though. Now look from above and make that motorway/highway junction 2D, not 3D (flatten it so roads cross over not travel by bridges) and you have a magic roundabout. (I've been comparing schematic diagrams of motorway  junctions vs. roundabouts.) What I mean here is not that the two look the same, but the same logic (unique route to each exit from each entrance) produces the same schematic for motorway junctions as it does for magic roundabouts.

* Or for that matter The junction on the Arlington side of Key bridge over the Potomac if you prefer - the world is full of junctions to choose from. (I have driven that one as well BTW, and got lost - I was trying to get to the Bull Run battlefields. They say D.C. is Hell on Earth. And you can't get out. Try as you might you find yourself driving back along Key bridge. Northwards.)

Okay you may ask - so why care anyway? I can manage perfectly well by simply building highway junctions with slipways.

Not if you don't have room for a bridge you can't. (Ends don't line up.) Or a tunnel (the city already has a tube/subway and that blocks the system). Or you have to demolish half the town to achieve it. As ST players - how many times have you had to totally 'terra form' a landscape just to get two ends of a bridge to meet?

So what use is it? Well, now imagine the roundabout is actually a one-way system you have set up in a town. (All the gaps in the roads might be filled with buildings). For example - imagine you have got a city centre with a central city block. Imagine that central block (containing perhaps a railway station or a cluster of industries) - then that is the 'central island' of the system. Then treat each route branching out from that as a mini roundabout (going round another block). This could be critical if you have lots of trucks/busses passing through the middle of town. What this does is allow us to create a 'model' for how we can set up one-way systems (model it as a magic roundabout!) I've noticed that setting up one-way systems is usually more a matter of trial and error (from reading posts here which seem to be closer to 'if it's a bit clogged, shove in a one way and hope' reply). Perhaps a 'good central theory' is needed?

Moreover, I've seen some indications (from first tests) that by placing bus stops at certain points, it provides a good 'webway' of interlinking bus routes. This seems to avoid the problems of a single massive terminus that gets overstuffed with passengers and collapses the whole system around if running the 'no overcrowding' rule (which I always do). Instead you end up with a 'collective terminus' of multiple stations and it is really hard to collapse the whole system. I'll try to write everything down once I've tried it all out - and notes on as to why things work out certain ways.

So, each if the entrance ways is a highway to another town, busses pass into town, move round the network (Say a big city centre area) placing down passengers and then head out to another town on another route. Each route will pass over 12 of the other 19 routes at some point in the system (for the mathematicians (like me :) ) it forms a geometric group of order 20). A single point, well chosen, could be a railway station for long-distance travel. No more than 1 interchange would be needed to get to the railway station (I've just drawn a big A2 schematic of the setup with coloured pens). A big station would of course be big enough to 'touch' many bus stops (so they are all the same stop). Pick that carefully and no interchanges are necessary (except to get off the bus and on the train.)

Quantifiable statistical results are needed first on a number of early points raised. I plan to set up a system to replicate all 20 routes. Each will be given a timetable to repeat the route 60 or 70 times (with 50 or 60 vehicles for each route consisting of vehicles of varying speeds). All the vehicles will be released at once and once the route is finished the vehicle will end at the depot. The time taken for all vehicles (crossing & re-crossing the intersection from all directions at once) to end back at the depot will be timed. (I.e. watch for the last vehicle to get back home and stop the clock). Then build a normal roundabout of similar size and repeat. Then try for a simple set of crossroads and T-junctions but no roundabout, etc.

And to think all this started with a flippant remark!



The most effective and efficient complex intersection i've seen was one in china, where 5 major streets mad at odd angles. No markings, no trafic controll. It worked by self organization, intense terror and ruthlessness (perhaps also homicide). In contrast, there were perfectly controlled right angle intersections, that broke completely down as soon as police was enforcing the rules, causing a complete gridlock.

i think it's their, historic, approach to what the rich, safe countries now re-discover as shared spaces.


I think those magic roundabouts are 'scary', because some genius thought it was a good idea to make a counter flow inner ring.

If that inner ring was filled in as a park, it would be one make it less daunting to navigate.

Oh, and there is much to be said about grade separating the counter flow ring to either above or below.
but then again, this requires actual money, instead of some road paint.
My Sketchup open project sources
various projects rolled up:

Colour safe chart:


Oh I can quite agree with many of the points raised with setting up the 'shared spaces'. (Although many town councils totally ruin it by putting it in the wrong place.) We've got a shared space in King's Lynn (not in the Wikipedia article) - it is a bloody nightmare on foot or by car. And like any system, it has its proponents (who always love it) and detractors (who hate it).

And also with Aeo's notes on magic roundabouts and the 'inner ring counter-gyratory'. As a note, putting the counter gyratory on a lower/upper level also needs the building space too.

Think instead like a series of cogs. If one cog is going clockwise the adjoining must go anticlockwise.

Alternatively, will link you to the site of the HH 'gyratory' (as they are officially called). Take a look at the map and the picture associated directly above the map. The central island, if large enough, is like a city block. It is a two-way road, just as normal, driving on the left. Or instead imagining the HH gyratory as just another road (2-way) travelling around a large park (the central island) with six mini roundabouts at the six corners.

In ST something is a roundabout only because one-way signs make it so. In RL, something is a roundabout only if someone says it is so. Then does the Inner London Ring road count? It goes right round the capital precinct from King's cross to Hyde Park to Victoria and Pimlico around Southwark and back through Tower Hamlets to King's Cross. It is a roundabout. It is also a two-way road - the inner carriageway of which is travelling counter-clockwise! And it has 18 mini roundabouts and 14 large ones. Look again at the map of Hemel Hempstead.

What makes Swindon difficult incidentally is that the central island is so small the next mini-roundabout is just 8 to 10 yards from the last.

But I do agree from a driving point of view.

What concerns me now is not "Do Magic roundabouts work in Real Life?" As "How can we use the logic structure to build a city centre one-way system in simutrans?" ST has a core logic (often not present in RL). It doesn't care if something is counter-intuitive (the reason a real Magic roundabout is confusing).

From early testing, there may yet be hope. By modelling the city centre appropriately, a good a free-flowing system can be built. And without needing an elevated or tunnelled inner counter-gyratory, but one that actually can work at normal ground level.




Quote from: sdog on November 05, 2013, 12:00:52 AM
i think it's their, historic, approach to what the rich, safe countries now re-discover as shared spaces.

Quote from: ekhmuel on November 05, 2013, 12:54:54 AM
Oh I can quite agree with many of the points raised with setting up the 'shared spaces'. (Although many town councils totally ruin it by putting it in the wrong place.) We've got a shared space in King's Lynn (not in the Wikipedia article) - it is a bloody nightmare on foot or by car. And like any system, it has its proponents (who always love it) and detractors (who hate it).

I think the closest we get around here are a few intersections in the center of town where the road surface is raised up to sidewalk level. In appearance, it's like a huge raised pedestrain crossing (itself a hybrid between a zebra crossing and a speed hump) filling the entire intersection like a pedestrian scramble (another rare concept in Norway), except without the markings. When the public asked whether vehicles had to yield to pedestrians, like in a normal raised pedestrian crossing, or if pedestrians had to wait until it was clear, like when crossing a road at places without zebra crossings, the authorities simply replied "You figure it out" or something to that effect. Fortunately, the road doesn't have much traffic. I use it for transitioning between cycling on the road and cycling on the sidewalk, often switching sides in the process, as there is more traffic at the next intersection.