Having the highway exits meet Main at intersections rather than on-ramps would allow two-way traffic on Main and also de-velocitize drivers coming off the highway.
By Ryan McGreal
Published April 26, 2016
One of the arguments we often hear against the two-way conversion of Main Street is that it would be too expensive and/or difficult to change the interchange with Highway 403. I don't want to guess at what the cost of such a change would be, but the difficulty and complexity seems to me to be quite minimal.
Here is a satellite map of Highway 403 (north-south highway bending down and to the left) where it crosses Main Street (left-right street at bottom) and King Street (left-right street at top):
Highway 403 interchange with Main and King Streets, exit ramps to Main highlighted (Image Credit: Google Maps)
I have highlighted the highway exits from eastbound (the red line coming up and right from the bottom left) and westbound (the red line coming down and to the right from the top centre).
As you can see, both ramps intersect Main Street at an angle, allowing highway drivers to merge right into the eastbound-only traffic on Main.
Both of these ramps run on the ground and at grade with Main Street before they actually reach the street. We can bend them to meet Main at a right angle without having to do any changes to a bridge or overpass. In the following map, I have highlighted the routes that these exit ramps can take to meet Main Street at right angles.
Highway 403 interchange with Main and King Streets, exit ramps to Main adjusted for right-angle intersection (Image Credit: Google Maps)
The two intersections would be around 150 metres apart, which is just far enough to put traffic signals at each intersection.
Having the highway exits meet Main at intersections rather than on-ramps accomplishes two things. First, obviously, it allows traffic to flow in both directions on Main Street. Second, it serves to de-velocitize drivers coming off the highway so that their internal sense of speed is reset for driving on city streets.
To double-check my analysis, I physically scouted the area where the highway exits meet Main Street and took some photos to demonstrate how plausible this is.
Here is the ramp from the westbound highway: you can see it bending to the left to merge with the eastbound traffic on Main.
Highway 403 westbound exit to Main Street bending east
Here's a view of the ramp looking east from Main Street:
Highway 403 westbound exit to Main Street, view from Main
The good news is that the spot where the exit ramp would have to bend to meet Main Street at a more perpendicular angle is already bare gravel.
Highway 403 westbound exit to Main Street, gravel beside ramp
The situation is similar when you look across the street to the exit ramp from the eastbound highway lanes.
Highway 403 eastbound exit to Main Street, view from across Main
The ramp comes off the highway and ramps gradually upward to meet Main Street at grade.
Highway 403 eastbound exit to Main Street looking up-ramp
Likewise, this exit ramp has no bridge or overpass to deal with, so it's a matter of bending the end of the ramp where it meets Main Street.
Highway 403 eastbound exit to Main Street, looking toward Main
In fact, it is not actually necessary to re-orient both exits to enable two-way traffic. The exit from the eastbound highway could be left as it is, with the restriction that vehicles exiting this way can only turn east onto Main. That is already the case today, so it would not further restrict turning movements for people driving cars.
Of course, the exit from the westbound highway definitely needs to change, because the current ramp intersection would have traffic merging the wrong way into the westbound lanes of Main Street.
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