I was wondering how common it was to have an arterial with outer roads, but all turns from the arterial are made from the outer roads at intersections. Example from Chicagoland:
Streetview: http://maps.google.com/maps?hl=en&ll=42.109757,-87.927103&spn=0.006527,0.016512&z=17&layer=c&cbll=42.109693,-87.927099&panoid=1HmliXAxcTiJhM5fUGqrEg&cbp=12,96.72,,0,5.73 (http://maps.google.com/maps?hl=en&ll=42.109757,-87.927103&spn=0.006527,0.016512&z=17&layer=c&cbll=42.109693,-87.927099&panoid=1HmliXAxcTiJhM5fUGqrEg&cbp=12,96.72,,0,5.73)
Aerial: http://maps.google.com/maps?hl=en&ll=42.109687,-87.926862&spn=0.001642,0.004128&t=k&z=19 (http://maps.google.com/maps?hl=en&ll=42.109687,-87.926862&spn=0.001642,0.004128&t=k&z=19)
Interestingly, Palatine Road is a narrow, shoulderless freeway east of this intersection for a little bit.
This particular setup is rather uncommon (usually a dual-dual surface road will have left turns from the inner lanes only), but it's closely related to the jughandle.
Never seen something quite like that before. An interesting setup. I think they had something like that in mind for some superarterials in the Vegas area, although they would've more resembled the freeway-like section east of the linked intersection.
I spy 3M signals at that intersection! :happy:
The George Washington Parkway in Virginia has something similar at its intersections with Slaters Lane and Bashford Lane in between Alexandria and Reagan Airport where all turns are made from the outer roads. I believe there used to be a traffic circle at the southern end Of the segment, but I don't know why (nor why it was changed). Traffic turning ONTO the Parkway is free to turn onto the thru lanes, BTW; it's only traffic ON the Parkway that must use the service roads to make any turns (left or right).
The separation between the main and service roads is slightly wider than what's shown above.
Don't think that I've ever seen an intersection in this configuration (until now).
Be well,
Bryant
Reminds me of "The Boulevard" in Philly
Commerce Ave (US 77) in Ardmore, OK has this kind of setup, complete with BGSs and exit gore signs for movements from the main street to the outer roads.
QuoteThe George Washington Parkway in Virginia has something similar at it's intersections with Slaters Lane and Bashford Lane in between Alexandria and Reagan Airport where all turns are made from the outer roads. I believe there used to be a traffic circle at the southern end Of the segment, but I don't know why (nor why it was changed).
Yes there was, at the equivalent of 2nd Street (one likely reason why VDOT's traffic log has VA 400 ending at 2nd St). Back in those days, the western frontage road was 2-way but not continuous, and the eastern frontage road did not exist. Also, 2nd St did not connect into the circle. The current configuration was built ca. 1962-1963.
The advantage of allowing all turns from the outer lanes vs. left turns from the inner lanes is that you get a separate signal phase for the outer lanes that makes it convenient for them to re-enter the main lanes (based on pavement wear I see in the aerial). Can't do that in Philly.
Quote from: froggie on July 25, 2011, 07:49:27 AM
QuoteThe George Washington Parkway in Virginia has something similar at it's intersections with Slaters Lane and Bashford Lane in between Alexandria and Reagan Airport where all turns are made from the outer roads. I believe there used to be a traffic circle at the southern end Of the segment, but I don't know why (nor why it was changed).
Yes there was, at the equivalent of 2nd Street (one likely reason why VDOT's traffic log has VA 400 ending at 2nd St). Back in those days, the western frontage road was 2-way but not continuous, and the eastern frontage road did not exist. Also, 2nd St did not connect into the circle. The current configuration was built ca. 1962-1963.
Thanks. The timeframe you cite is a major reason why I don't remember it, as I wasn't yet born then.
BTW, I failed to note that one difference with the GW Parkway spot I mentioned is that cars on the outer roads may not move to the inner roads at either intersection, but that configuration is only for a short distance anyway. (I know froggie knows this, but other readers may not know the spot.)
Quote from: Steve on July 26, 2011, 07:02:46 PM
The advantage of allowing all turns from the outer lanes vs. left turns from the inner lanes is that you get a separate signal phase for the outer lanes that makes it convenient for them to re-enter the main lanes (based on pavement wear I see in the aerial). Can't do that in Philly.
But can the opposing left turns from the outer lanes happen at the same time? It didn't really seem like it from my quick scan of the aerial. That implies split phasing for the outer lanes, which can dramatically increase signal cycle length...