[OSM-talk] Turn restrictions vs allowances?

[Matias D'Ambrosio]

On Wednesday 22 October 2008 18:06:10 you wrote:
> Matias D'Ambrosio wrote:
> >Sent: 22 October 2008 8:21 PM
> >To: talk at openstreetmap.org
> >Subject: [OSM-talk] Turn restrictions vs allowances?
> >
> > What is the opposite of a turn restriction? I can't find it and no one
> >answers on IRC.
> > Turning left is forbidden everywhere in my country on two way roads when
> >there is no specific traffic light for it, and I assume it's the same in
> >many
> >other countries.
>
> Interesting, which country are you talking about since clearly it does
> differ around the world. Essentially in the UK you can turn left or right
> at any junction, with or without a traffic signal. Generally the only time
> you cannot is when a no left turn or no right turn sign is present. I'm
> guessing that the reason the "turn restrictions" tagging has come about is
> because most countries are the opposite to yours rather than the same?
 Weird, apparently people in other countries have respect for each other ;-)
 I'm in Argentina, some things are great (street numbers), some things are 
like this.
 I'm a bit confused about the wording of the law, though. It talks about this 
restriction applying to ways "regulated by traffic lights", by which it might 
mean it applies at intersections with traffic lights, or not. The law is not 
respected, if it applies, when far from downtown.
 Also, three provinces have their own laws, but at least in the case of Buenos 
Aires the national and provincial law say the same in this case. The national 
law that mentions this is law 24449 in 44.f which can be read:
http://www.vialidad.gov.ar/legislacion_de_transito/Ley 24449.pdf

"ARTICULO 44.-VIAS SEMAFORIZADAS. En las vías reguladas por semáforos: 
a) Los vehículos deben: 
1. Con luz verde a su frente, avanzar; 
2. Con luz roja, detenerse antes de la línea marcada a tal efecto o de la 
senda peatonal, evitando luego cualquier movimiento; 
3. Con luz amarilla, detenerse si se estima que no se alcanzará a transponer 
la encrucijada antes de la roja; 
4. Con luz intermitente amarilla, que advierte la presencia de cruce riesgoso, 
efectuar el mismo con precaución; 
5. Con luz intermitente roja, que advierte la presencia de cruce peligroso, 
detener la marcha y sólo reiniciarla cuando se observe que no existe riesgo 
alguno; 
6. En un paso a nivel, el comienzo del descenso de la barrera equivale al 
significado de la luz amarilla del semáforo; 
b) Los peatones deberán cruzar la calzada cuando: 
1. Tengan a su frente semáforo peatonal con luz verde o blanca habilitante; 
2. Sólo exista semáforo vehicular y el mismo de paso a los vehículos que 
circulan en su misma dirección; 
3. No teniendo semáforo a la vista, el tránsito de la vía a cruzar esté 
detenido. 
No deben cruzar con luz roja o amarilla a su frente; 
c) No rigen las normas comunes sobre el paso de encrucijada; 
d) La velocidad máxima permitida es la señalizada para la sucesión coordinada 
de luces verdes sobre la misma vía; 
e) Debe permitirse finalizar el cruce que otro hace y no iniciar el propio ni 
con luz verde, si del otro lado de la encrucijada no hay espacio suficiente 
para sí. 
f) En vías de doble mano no se debe girar a la izquierda salvo señal que lo 
permita."

 44.d in particular is clearly not just for the intersections, though I'd be 
inclined to think 44.f is only for intersections with traffic lights.
 As I said on IRC, this is quite similar to the saying "two wrongs don't make 
a right, but three lefts do", only the other way around :-)
 I think simply having "allowance" instead of "restriction" would work, and 
then let routing programs figure out what laws apply. They have to know the 
country for speed limits and other things anyway.