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Roads: Ontario/GTA Highways Discussion

I've noticed a common construction staging method for a lot of highway interchanges and overpasses build a new overpass off to the side of the existing arterial road, reroute the road to use the new bridge, then demolish the old road. Is the main reason to save construction costs from building a temporary road off to the side to replace the existing alignment? Do terrain and environmental conditions also a factor when choosing alignment?

I know it doesn't impact much in the grand scheme of things, but it causes the road grid at the highways to curve a little bit and looks "unnatural" when you're viewing satellite maps and see the unaligned roads.
 
Is the main reason to save construction costs from building a temporary road off to the side to replace the existing alignment? Do terrain and environmental conditions also a factor when choosing alignment?
I always thought it was so they can minimize road closures as traffic can use the old bridge while the new one is built. Random guess but it might also be faster as work on the new bridge can start without the old one being demolished.
 
I've noticed a common construction staging method for a lot of highway interchanges and overpasses build a new overpass off to the side of the existing arterial road, reroute the road to use the new bridge, then demolish the old road. Is the main reason to save construction costs from building a temporary road off to the side to replace the existing alignment? Do terrain and environmental conditions also a factor when choosing alignment?

I know it doesn't impact much in the grand scheme of things, but it causes the road grid at the highways to curve a little bit and looks "unnatural" when you're viewing satellite maps and see the unaligned roads.
The cost to construct a 'temporary' structure that would be suitable for public use for several months would probably approach that of the permanent one, so they would essentially constructing two. It's not like they can toss up a couple of 'Bailey Bridges'. There are often a lot of underground infrastructure lines that would need to be relocated - twice.
 
I've noticed a common construction staging method for a lot of highway interchanges and overpasses build a new overpass off to the side of the existing arterial road, reroute the road to use the new bridge, then demolish the old road. Is the main reason to save construction costs from building a temporary road off to the side to replace the existing alignment? Do terrain and environmental conditions also a factor when choosing alignment?
Yes. Keeping costs down and minimizing disruption to daily transportation activities as much as possible is a priority for pretty much all road construction projects these days.

New Overpass Construction -> Road/Utility Realignment -> Demolition is much more efficient than Demolition -> Overpass Reconstruction. That way you don’t have to shut down an entire road for an indeterminate amount of time while you rebuild the overpass. With the faster method, you only have to shut down while the lane switchover and demolition is occurring, which can be done as quickly as one night.
 
If I may add, if it is a low volume secondary route, or there is simply no space to move it laterally, they generally will simply shut it down. Up this way, the Anne St./400 overpass (no interchange) was simply torn out as there is no room to alter the alignment and there are reasonable traffic alternatives. On the other hand, West St./Hwy 11 in Orillia is being shifted. What will be interesting to me is when they re-build Dunlop and Bayfield interchanges. While there might be enough space to shift Dunlop to the south (with some expropriation), I don't see many options for Bayfield, and shutting it down will be highly disruptive.
 
I don't see many options for Bayfield, and shutting it down will be highly disruptive
1669236612517.png

It's doable, if you use Rose St a bit and meander Bayfield through the interchange on a temporary bridge. The old loop ramp can also be used temporarily
 
View attachment 440565
It's doable, if you use Rose St a bit and meander Bayfield through the interchange on a temporary bridge. The old loop ramp can also be used temporarily
"Doable" perhaps, but then they would be into the 'build-two-bridges; tear-down-one' which was the original question. I'm not sure they will do that but don't really know. It would certainly disrupt flow and some of the suggested angles and clearances would be very tight. It would also likely cost the eb/sb ramp, and the n/b ramp/Rose St. intersection is right at the bridge for construction purposes.

When you consider the gradients and spans involved, traffic loads and a whole host of other engineering and liability factors, I don't think the concept of 'temporary bridge' is realistic but, again, who knows.
 
If I may add, if it is a low volume secondary route, or there is simply no space to move it laterally, they generally will simply shut it down. Up this way, the Anne St./400 overpass (no interchange) was simply torn out as there is no room to alter the alignment and there are reasonable traffic alternatives. On the other hand, West St./Hwy 11 in Orillia is being shifted. What will be interesting to me is when they re-build Dunlop and Bayfield interchanges. While there might be enough space to shift Dunlop to the south (with some expropriation), I don't see many options for Bayfield, and shutting it down will be highly disruptive.

There was some very unique I would say options for Dunlop Staging. Shifting south, Shifting north. or building the outsides first. It was challenging design, space constraints on highway 400 don't help either.
 
IIRC MTO is expropriating a bunch of properties to shift Bayfield.
This would make sense, it would be very difficult to fit an interchange with modern design standards into that existing footprint.
 
This would make sense, it would be very difficult to fit an interchange with modern design standards into that existing footprint.
I looked up the plans - see below. Basically all the houses on the east side of Bayfield south of the 400 are going to go bye-bye. Even with the expropriation though, it still looks like it's going to be a fairly complex replacement process with half of the new bridge built first, traffic shifted onto it, then the remaining half built, as it still partially overlaps with the existing bridge. The Shell gas station on the north side of the 400 is also getting expropriated.

Bayfield.png


Dunlop has just as much if not more expropriation as well, taking out several plazas around the interchange.
 
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I looked up the plans - see below. Basically all the houses on the east side of Bayfield south of the 400 are going to go bye-bye. Even with the expropriation though, it still looks like it's going to be a fairly complex replacement process with half of the new bridge built first, traffic shifted onto it, then the remaining half built, as it still partially overlaps with the existing bridge. The Shell gas station on the north side of the 400 is also getting expropriated.

View attachment 440863

Dunlop has just as much if not more expropriation as well, taking out several plazas around the interchange.
Thanks for that. It's going to be a tight job and, as I suspected, no major re-alignment of Bayfield to accommodate a new bridge while the existing is still in service. Bayfield is fairly jammed at the best of time, especially in the summer, so it's going to be a place to avoid.
 
The RFP for Phase II of the Highway 3 twinning in Essex County has closed. Two teams have been shortlisted - GIP Paving Inc. (formerly Coco Paving Inc. and also the current contractor for Phase I) and Erie Shores Infrastructure Partners. The winning bidder will be announced in spring 2023.
 

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