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The Bowtie Intersection is finally getting its moment in the sun

Started by kernals12, November 25, 2020, 09:50:40 AM

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kernals12

Quote from: kphoger on October 21, 2022, 03:24:09 PM
Quote from: kernals12 on October 21, 2022, 03:20:03 PM
So he's advocating *for* more car accidents?

Only inasmuch as you're advocate for pedestrian fatalities.

Left turns are dangerous for cyclists and pedestrians too.


kernals12

Quote from: tradephoric on February 24, 2021, 08:01:52 AM
Quote from: kernals12 on November 25, 2020, 09:50:40 AM
At some point in the near future, the people of Prince William County, Virginia will bear witness to a great revolution in traffic engineering. The VDOT plans to turn the current intersection between the Prince William Parkway and Clover Hill Road into a Bowtie Intersection and it is a thing of beauty


2 roundabouts will be installed on Clover Hill on opposite sides of the Parkway. All Left Turns at the main intersection will be prohibited and instead drivers will use the roundabouts to make a u turn to complete their movements. It's essentially an at-grade version of a dogbone interchange. It means the main intersection can use a simple 2 phase signal. It improves traffic capacity and safety.

There are many so-called innovative intersections that do the same thing such as the RCUT, the Michigan Left, the Jughandle, and the Continuous Flow Intersection, but those require a massive amount of right-of-way. This does not, in fact, as you can see, by getting rid of the need for left turn lanes, it takes up less space than a conventional intersection. I hope that this is the beginning of a glorious revolution.

Here's a Median U-turn intersection in Michigan with the same median width as Prince William Pkwy.  Admittedly I'm a little partial to Median U-turns but i don't see much advantage going with the BowTie intersection in the OP's example.


https://www.google.com/maps/@42.7520685,-83.2466276,545m/data=!3m1!1e3
Quote from: 1 on February 24, 2021, 08:15:17 AM
Quote from: kernals12 on February 24, 2021, 08:07:56 AM
Notice those loons. That means traffic going straight on the main road has to stop for those making a u turn. With the bowtie, all movements are done on the minor road so the smooth procession of traffic on the major road is uninterrupted.

The U-turn points usually aren't signalized; this one appears to be a rare exception. Usually, if you're on the U-turn ramp, you just merge when you can. (Some median U-turn intersections add a lane for U-turners so that they don't have to wait for a gap in traffic.)
There are 2 advantages I can think of

1. It means vehicles making u-turns aren't doing it on a highway

2. Those roundabouts could be repurposed to provide access to future commercial development.

Evan_Th

It's been two years since this thread started; has there been any movement on actually building these roundabouts?

bootmii

Quote from: 1995hoo on October 21, 2022, 03:38:50 PM
For what it's worth, the speed limit on there is 55, but traffic typically moves closer to 70 mph. I try to keep it to 60—65 when I go through that area and I don't wind up passing very many people at all.

This needs a freeway treatment then. Don't even have a bowtie, just have a diamond interchange. (Perhaps double-deck the through lanes over/under the turn lanes and the cross street?) If it has high enough conflicting volumes that VDOT is even considering the bowtie, and the prevailing speed is 70, just build an interchange at that point.
Born again roadgeek from California.



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