Interchange Ideas for Freeways & Arterials ODOT Roadway Conference April 13, 2010

New Interchange Ideas Many arent actually new – ODOT just hasnt used them up until now. Nor have many others. Many arent actually new – ODOT just hasnt used them up until now. Nor have many others. Sometimes for good reasons. Some ideas are appropriate for freeways only, some for arterial roadways only, and some might work in either context. Some ideas are appropriate for freeways only, some for arterial roadways only, and some might work in either context. If the stars are properly aligned. Its always necessary to look at the specifics of your situation… a reasonable idea plopped down in an inappropriate spot will likely not work well. Its always necessary to look at the specifics of your situation… a reasonable idea plopped down in an inappropriate spot will likely not work well. Many of these ideas are basically an attempt to squeeze more out of the ramp intersections. Many of these ideas are basically an attempt to squeeze more out of the ramp intersections. And stretch $$$$$

Caveat Emptor Not every innovation works out. Sometimes we learn from our mistakes. Its wiser to learn from the ones already made than to create a bunch of new ones trying to be clever. Never stop thinking!

Highway Interchanges Single Point (SPI or SPUI) Single Point (SPI or SPUI) Tight Diamond (TDI) Tight Diamond (TDI) Diverging Diamond – DDI (aka Crossing or Double Crossover) Diverging Diamond – DDI (aka Crossing or Double Crossover) Contraflow Left Contraflow Left Roundabout Ramp Intersections Roundabout Ramp Intersections 3-Level Stacked Diamond – Freeway Only 3-Level Stacked Diamond – Freeway Only Split Interchanges Split Interchanges

Arterial Interchange Ideas Single Loops & Jug Handles Single Loops & Jug Handles Grade Separated Roundabouts Grade Separated Roundabouts Partially Grade Separated Intersections Partially Grade Separated Intersections Echelon Interchange Echelon Interchange Frontage Systems – Usually include U-Turn Provisions (Such as Texas Turnarounds) Frontage Systems – Usually include U-Turn Provisions (Such as Texas Turnarounds)

Interchange Type Freeway Only Arterial Only Could Work for Either Used in OR? Single Point X Yes - 2 Tight Diamond X Yes - 1 Diverging Diamond X Coming Soon - 1 Contraflow Left XNo Roundabout Ramp Intersections X Not Yet by ODOT Stacked Diamond XNo Jug Handle XYes Grade Separated Roundabout X*No Grade Separated Intersection XNo EchelonXNo Frontage Systems X*Limited Split Interchanges X Coming (Maybe)

Single Point Market St. in Salem

SPI Intersection

Tight Diamond

Sylvan Interchange Tight Diamond Configuration US Scholls Ferry/Skyline in Portland

Diverging Diamond

Contraflow Left

Roundabout Ramp Intersections I-70 in Avon, CO

3-Level Stacked Diamond Lubbock, TX US 82/US 289

Split Interchanges

Single Loop/Jug Handles Greeley Going St. NE Portland

Single Loop/Jug Handle Examples Greeley Going St. (Portland)- Greeley Going St. (Portland)- East End of Ross Isl. Br. (Portland)- < East End of Ross Isl. Br. (Portland)- < OR OR 204 (near Weston) OR OR 204 (near Weston) US Colorado Ave. (Bend) US Colorado Ave. (Bend) OR Biddle Rd. (Medford) OR Biddle Rd. (Medford) OR N. Front St. (Woodburn) OR N. Front St. (Woodburn)

Grade Separated Roundabouts Uncommon in US – Ubiquitous in UK

Intersection Grade Separation

Echelon Interchange Only known example – US Biscayne Blvd. in Aventura, Florida – near Miami

Frontage Road Systems Fairly common in Texas & some major Midwest cities – mostly on freeways – both rural and urban Fairly common in Texas & some major Midwest cities – mostly on freeways – both rural and urban ODOT stuff tends to be connections or extensions of cut-off roadways, not directly integrated to the mainline, except for a few spots in Portland ODOT stuff tends to be connections or extensions of cut-off roadways, not directly integrated to the mainline, except for a few spots in Portland AASHTO Chapters 7 & 8 (Arterials & Freeways) have some discussions on frontage systems AASHTO Chapters 7 & 8 (Arterials & Freeways) have some discussions on frontage systems

Frontage Examples I-35 in San Marcos, TX

Frontage Examples Detroit, MI Freeways – Incl. a wide variety of U-turn provisions Detroit, MI Freeways – Incl. a wide variety of U-turn provisions Many Texas Rural Freeways Many Texas Rural Freeways Texas Turnarounds another U-turn variation. Texas Turnarounds another U-turn variation.

And Now Heres Something We Hope Youll Really Like… The Diverging Diamond Watch me pull a rabbit out of my hat.

Fern Valley Interchange – I-5 Exit 24 Image Stolen From Bob Branchs Design – March 2010

SR 13 – Springfield, MO Photos Courtesy of Don Saiko, MoDOT First Completed DDI in the US – Opened to Traffic in Late June 2009 (Before Construction was completed in July)

Main – American Fork, UT Photos from UDOT Project Website Rendering of Final ProductFebruary 2010 Const. Photo Currently Under Construction – North of Ogden

Diverging Diamond – The Tradeoffs Advantages include: Very effective in moving heavy LT demands - esp. compared to other diamond types – Two phase signals at intersections – Less vehicle queuing. Very effective in moving heavy LT demands - esp. compared to other diamond types – Two phase signals at intersections – Less vehicle queuing. Usually has a narrower X-Section on X-Road – extra LT lanes, etc. not needed – but the median area may be fairly wide anyway (for other reasons). Usually has a narrower X-Section on X-Road – extra LT lanes, etc. not needed – but the median area may be fairly wide anyway (for other reasons). Probably will work for either Freeways or Arterials – assuming that downstream intersections dont back up to the ramps. Probably will work for either Freeways or Arterials – assuming that downstream intersections dont back up to the ramps.Disadvantages No up and over movement is possible at the ramp intersections – U-turns necessary on X-Road. No up and over movement is possible at the ramp intersections – U-turns necessary on X-Road. When LT and Opposing thru movements are both very heavy, TPAU analysis has shown some operational issues that crop up. When LT and Opposing thru movements are both very heavy, TPAU analysis has shown some operational issues that crop up. Extensive channelization, signing, markings are required for the ramp intersections – the intersection geometry can be tricky, esp. when the underlying roadway is in a horizontal curve. Extensive channelization, signing, markings are required for the ramp intersections – the intersection geometry can be tricky, esp. when the underlying roadway is in a horizontal curve. Access Management is just as necessary as with any other idea Access Management is just as necessary as with any other idea - Dont overlook it!

Q & aQ & aQ & aQ & a Were ready for grilling.