Subject: Roundabouts on divided, high speed arterials

 

 

Greetings,

 

 

Does anyone have examples of existing roundabouts which have been built on a

high speed (50mph and up) arterial or controlled access expressway with a

divided median?  Typically, this type of facility would have at-grade

intersections spaced at half mile to one mile intervals and very limited to

no driveway access.  I'm looking for examples within the United States only

that are located preferably in a rural or semi-rural setting.  Thanks in

advance.

 

 

 

 

Steven Diebol, E.I.T.

Transportation Engineer/Planner

DLZ Michigan, Inc.

(517) 393-6800 ex. 453

sdiebol@dlz.com 

 

 

I assisted the WIDOT with this roundabout that opened fall 2008 after a

number of fatalities occurred at this intersection.

 

 

85% speeds on USH 18 were ~65 pre-roundabout (posted at 55).

 

 

The approach of this roundabout provides strong visual queues as to the

changing road condition ahead (roundabout) this is achieved thru roadway

approach curvature (appropriate for speeds) and also significant effort in

landscaping.

 

 

Signals warrants were not terribly solid based on existing traffic...but

growth is marching out toward this area and were met on design year flows...

 

 

Traffic section did not want to put in a signal due to high speeds and

potential for serious rear-ends...DOT had planned a ~$15M interchange, City

didn't want that due to land-use issues.

 

 

The roundabout was relatively expensive due to the approach re-alignment

needs (to include rock blasting on approach and fill needs in one of the

quadrants), and also landscaping. It came in at ~$2.2M.

 

 

 

Mark T. Johnson, P.E.

MTJ Engineering, LLC

Achieving Traffic & Transportation Solutions:

Specializing in Modern Roundabout Planning and Design

 

313 Price Place, #205

Madison, WI 53705

Office - 608 238-5000

Cell    - 608 669 5009

www.mtjengineering.com

---

Steven-

 

 

The roundabout on SH 82 just on the west side of Aspen, CO  kind of fits the criteria.  The speed limit leading up to it (from the west) is 55 or 45, then is signed down to 35 as you get closer to the RBT.  Of course, most drivers go 45 right up to where they actually have to slow down.  The aerial looks slightly dated, the streetview shows some construction/widening to get 4 lanes all the way from the airport to the RBT (I think one lane in each direction is a bus lane.).

 

 

 

 

David Woolfall, PE, PTOE

TSIOUVARAS SIMMONS HOLDERNESS

5690 DTC Blvd.

Suite 345 W

Greenwood Village, CO  80111

(p)303-771-6200

(f) 303-771-6800

(c) 303-704-5698

email  david.woolfall@tshengineering.com

 

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From:    Bill Hange <HangeB@CI.LOVELAND.CO.US>

Subject: Re: Roundabouts on divided, high speed arterials

 

 

Larimer County Roads 9/30 just northeast of Loveland, Colorado near the north end of the airport (n/s runway).  Approaches e/w were 55 mph before installation last year.  This roundabout opened around Labor Day last year. See article our section's (COWYITE.ORG) our local ITE Newsletter   

http://www.cowyite.org/newsletters/2009%20October.pdf=

 

 

Bill Hange

Loveland 

---

Pioneer Parkway and Hayden Bridge Way, Springfield, Oregon.

 

 http://www.ci.springfield.or.us/Pubworks/Martin_Luther_King_Webpage_files/mlk_project.html

 

- Scott Batson

---

With this message I am reminding listserve users of NCHRP Report 613:

Guidelines for Selection of Speed Reduction treatments at High Speed Intersections.

 

Here is a blurb from NCHRP and the link to the report.

 

"TRB's National Cooperative Highway Research Program (NCHRP) Report 613:

Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections explores the effectiveness of geometric design features as well as signage and pavement markings to reduce vehicle speeds at high-speed intersections."

 

http://www.trb.org/Main/Blurbs/Guidelines_for_Selection_of_Speed_Reducti

on_Treatm_160046.aspx

 

The document provides a framework for understanding the relationship between the roadway segment and the intersection proper and how to evaluate the site specific needs for considering treatments to best blend the operations between the segment and the intersection.  Of course roundabouts provide a wonderful slow speed environment at the "node" and NCHRP 613 can help identify some of the possible treatment needs to transition from the high-speed segment adjacent to the intersection.

 

 

Brian L. Ray

Principal Engineer

Kittelson & Associates, Inc.

610 SW Alder Street, Suite 700

Portland, OR 97205

www.kittelson.com

bray@kittelson.com

503.228.5230