Quote:
Originally Posted by sa230e
From the PDF above and what sonysnob said they already seem to be designed to save money.
How do those loop ramps on the 407 cloverstacks stand-up? Do they handle the traffic alright? Are full directional ramps badly needed there? I don't go to Toronto much and when I do, I don't use the 407 so I don't know.
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From my experiences I'd say the loops at the 404 and 410 interchanges are alright. The loops probably have higher accident rates than a flyover would, however.
In my opinion, however, the loop ramps at the 427/407 interchange are a problem. As was stated within the document I referenced above, the loops are extremely tight, with a design speed of about 36km/h. Because the 427 currently ends at Hwy 7, neither of the loops seem to carry that much traffic. (They serve the westbound -> northbound and southbound to westbound movements). Once the 427 is extended, and particularly once the 427 is tied into GTA west freeway, traffic on the loops will grow considerably.
I am not sure the decision making process that went into building these loops. The structures that carry the 427 over the 407 are fairly narrow, and don't seem to be designed wide enough for a permanent speed change lane. The structures lack a right side shoulder, and I am not even sure if the lane width for the speed change lanes is as wide as is should be.
I do know, the structures that carry the 427 over the 407 were built well in advance of the rest of the 407, though to be honest, I am not exactly sure what the significance of pre-building these structures has to the final design of the highway.
From looking at the interchange, I am not sure if the MTO could fit a southbound -> eastbound flyover underneath the current westbound -> southbound structure should they want to replace the southbound loop ramp. Replacing the loop rams would also conflict with the Highway 7 interchange and overpass which is located a short distance to the north of the 407. Interestingly, the westbound -> southbound flyover structure was also built several years before the rest of the highway. In fact, the westbound -> southbound flyover between the 407 and 427 was finished before the southbound -> eastbound 427 to 409 flyover replaced the traffic lights on the 427.
The design and construction of the 407 is probably the most interesting events in the history of Ontario's highway network. Another interesting interchange is the 403/407 interchange in Mississauga. Some of the grading is still visible for the ramps that formerly served the Trafalgar Road connector. Also, the long westbound 403 flyover was built with an extraordinarily narrow deck for a two lane ramp. Obviously a huge problem now that it will forever carry the westbound mainline lanes of the 403. It will be damn near impossible to rehabilitate that ramp when the time comes.
... sorry if that made anybody's head explode. I could talk about the 407 all day.