Modern roundabout or Traffic Circle?

[vdeane]

If you have to change lanes in the circular roadway to exit, it's not a modern roundabout.

Depends on how you mean. If you mean there is a parallel lane like in a cloverleaf interchange, then it's true, otherwise false (multi-lane roundabouts).

A properly-designed, multi-lane modern roundabout does not require a lane change to exit. The markings within the circulating roadway should channel drivers outwards as appropriate.

Then in that case, any two-lane circles/rotaries/roundabouts do not qualify as modern roundabouts. Why have the inside lane, then, which would require two lane changes, to enter the lane and then to exit the roundabout?

The lanes are striped such that the inner lane moves outward at the major exits.
https://www.google.com/maps/@42.636931,-73.8562964,150m/data=!3m1!1e3

[6a]

If I had run across this while driving, or seen the picture without context, I would have called it a roundabout.

[riiga]

A properly-designed, multi-lane modern roundabout does not require a lane change to exit. The markings within the circulating roadway should channel drivers outwards as appropriate.

Such markings are typically used in turbo roundabouts, while regular roundabouts don't have them. I guess (multi-lane) modern American roundabouts are more turbo roundabout like than standard multi-lane roundabouts. Standard multi-lane roundabout. Turbo roundabout.

[froggie]

Then in that case, any two-lane circles/rotaries/roundabouts do not qualify as modern roundabouts. Why have the inside lane, then, which would require two lane changes, to enter the lane and then to exit the roundabout?

Not true.  Plenty of 2-lane roundabouts where you can legally (and via striping) exit from the inside lane.

[english si]

So, for example, you'll find hundreds of roundabouts in the UK that are signed at the national speed limit (60 or 70 mph)

The UK doesn't put specific speed limits for merely the duration of the intersection.

I believe the limit is 60mph, as a one-way road, rather than a dual carriageway. There's only a small number of roundabouts where that is possible to travel around the roundabout at that speed* - typically traffic signals have been added to busy large roundabouts, though sometimes smaller roundabouts have been added to make 'magic roundabouts' (and, in the case of Denham Roundabout, M40 J1: some of both).

*Rather than just plowing through taking a 'racing line' straight through. I've endured a driver doing ~100mph on the A43 who only slowed down a little for the roundabouts as it was empty and he could take the path of least deflection. Still was a jolt left followed by a jolt right and not comfortable.

[vdeane]

A properly-designed, multi-lane modern roundabout does not require a lane change to exit. The markings within the circulating roadway should channel drivers outwards as appropriate.

Such markings are typically used in turbo roundabouts, while regular roundabouts don't have them. I guess (multi-lane) modern American roundabouts are more turbo roundabout like than standard multi-lane roundabouts. Standard multi-lane roundabout. Turbo roundabout.

The "standard multi-lane" is considered a traffic circle on this side of the pond.  The Turbo one looks like a modern roundabout with a barrier between lanes and a non-circular center island.

[froggie]

The "standard multi-lane" is considered a traffic circle on this side of the pond.

If you consider that inside "sidewalk" to be a truck apron and adjust the lane striping to MUTCD-standard, then I would say yes that's more a roundabout than a traffic circle.

[jakeroot]

Such markings are typically used in turbo roundabouts, while regular roundabouts don't have them. I guess (multi-lane) modern American roundabouts are more turbo roundabout like than standard multi-lane roundabouts. Standard multi-lane roundabout. Turbo roundabout.

Washington State used to have a modern roundabout painted like your first example, and WSDOT noticed that no one was using the inside lane because they felt obligated to exit only from the outside lane. You can see the "cat tracks" are much heavier in the outside lane.

Some might say that this isn't a modern roundabout, but WSDOT's chief engineer Brian Walsh says it is, given the entry deflection and that it was built circa 2001. Unlike later designs, these earlier roundabouts used European guidelines, hence the pavement markings. Later designs used Aussie design standards.



Gig Harbor, WA / WA-16 at Burnham Drive

As much as I like this traditional design, I would rather have no lanes lines than non-spiraling lines. Here's my preferences, in order from most to least preferred, for pavement markings:

1. no lane lines
2. spiral/turbo lane lines
3. traditional style

[jeffandnicole]

Some might say that this isn't a modern roundabout, but WSDOT's chief engineer Brian Walsh says it is, given the entry deflection and that it was built circa 2001.

It has some features making it a modern roundabout, but it's not.  There's no point where the inside lane directs people to an exit.

And it's a modern roundabout because it was built in 2001?  Um...

[jakeroot]

Some might say that this isn't a modern roundabout, but WSDOT's chief engineer Brian Walsh says it is, given the entry deflection and that it was built circa 2001.

It has some features making it a modern roundabout, but it's not.  There's no point where the inside lane directs people to an exit.

"Modern" in context; the design was considered state of the art (by European standards) when it was constructed.

And it's a modern roundabout because it was built in 2001?  Um...

Traffic circles were essentially dead before the turn of the century. Most roundabouts built since the 90s were built with "modern roundabout" intentions, as far as I'm concerned.

[froggie]

It has some features making it a modern roundabout, but it's not.  There's no point where the inside lane directs people to an exit.

Mainly because the striping is subpar, but one could technically exit from the inside lane to the east/right-side-of-the-image.

And it's a modern roundabout because it was built in 2001?  Um...

That's around the time that modern roundabouts began to take root in the U.S.  MnDOT built their first in 2002.

[tradephoric]

That's around the time that modern roundabouts began to take root in the U.S.  MnDOT built their first in 2002.

By 2002, there was roughly 400 modern roundabouts in the US.  Colorado built a lot of modern roundabouts before 2000.

[ScottRAB]

Here's a link to the FHWA typical lane markings of Modern Roundabouts.
Picture diagrams from the MUTCD: http://mutcd.fhwa.dot.gov/htm/2009/part3/part3c.htm

The lane use signs and lane markings should reinforce each other and tell people driving which lane can do what.  You choose the lane to enter an intersection based on where you want to end up, just like at a signalized intersection.