interchange ideas for freeways & arterials odot roadway conference april 13, 2010

Interchange Ideas forInterchange Ideas forFreeways & ArterialsFreeways & Arterials

ODOT Roadway ConferenceApril 13, 2010

““New” Interchange IdeasNew” Interchange Ideas Many aren’t actually new – ODOT just hasn’t Many aren’t actually new – ODOT just hasn’t

used them up until now. Nor have many used them up until now. Nor have many others.others.Sometimes for good reasons.Sometimes for good reasons.

Some ideas are appropriate for freeways only, Some ideas are appropriate for freeways only, some for arterial roadways only, and some some for arterial roadways only, and some might work in either context.might work in either context.If the stars are properly aligned. If the stars are properly aligned.

It’s It’s alwaysalways necessary to look at the specifics of necessary to look at the specifics of your situation… a “reasonable” idea plopped your situation… a “reasonable” idea plopped down in an inappropriate spot will likely not down in an inappropriate spot will likely not work well.work well.

Many of these ideas are basically an attempt to Many of these ideas are basically an attempt to squeeze more out of the ramp intersections. squeeze more out of the ramp intersections. And stretch $$$$$And stretch $$$$$

Caveat EmptorCaveat Emptor

Not every innovation works out.Not every innovation works out.Sometimes we learn from our mistakes.Sometimes we learn from our mistakes.It’s wiser to learn from the ones already made It’s wiser to learn from the ones already made than to create a bunch of new ones trying to be than to create a bunch of new ones trying to be “clever”.“clever”.Never Never stop thinking!stop thinking!

Highway InterchangesHighway Interchanges

Single Point (SPI or SPUI)Single Point (SPI or SPUI) Tight Diamond (TDI)Tight Diamond (TDI) Diverging Diamond – DDI (aka Diverging Diamond – DDI (aka

“Crossing” or “Double Crossover”)“Crossing” or “Double Crossover”) Contraflow Left Contraflow Left Roundabout Ramp IntersectionsRoundabout Ramp Intersections 3-Level “Stacked” Diamond – 3-Level “Stacked” Diamond –

Freeway OnlyFreeway Only Split Interchanges Split Interchanges

Arterial “Interchange” Arterial “Interchange” IdeasIdeas

Single Loops & Jug HandlesSingle Loops & Jug Handles Grade Separated RoundaboutsGrade Separated Roundabouts Partially Grade Separated Partially Grade Separated

IntersectionsIntersections Echelon InterchangeEchelon Interchange Frontage Systems – Usually Frontage Systems – Usually

include U-Turn Provisions (Such include U-Turn Provisions (Such as “Texas Turnarounds”)as “Texas Turnarounds”)

InterchanInterchange Typege Type Freeway Freeway

OnlyOnlyArterial Arterial

OnlyOnly

Could Could Work for Work for

EitherEitherUsed in Used in

OR?OR?

Single PointSingle Point XX Yes - 2Yes - 2

Tight Tight DiamondDiamond XX Yes - 1Yes - 1

Diverging Diverging DiamondDiamond XX

Coming Soon - Coming Soon - 11

Contraflow Contraflow LeftLeft XX NoNo

Roundabout Roundabout Ramp Ramp

IntersectionsIntersectionsXX

Not Yet by Not Yet by ODOTODOT

Stacked Stacked DiamondDiamond XX NoNo

Jug HandleJug Handle XX YesYes

Grade Grade Separated Separated

RoundaboutRoundaboutX*X* NoNo

Grade Grade Separated Separated

IntersectionIntersectionXX NoNo

EchelonEchelon XX NoNo

Frontage Frontage SystemsSystems X*X* LimitedLimited

Split Split InterchangesInterchanges XX

Coming Coming (Maybe)(Maybe)

Single PointSingle PointI-5 @ Market St. in SalemI-5 @ Market St. in Salem

SPI IntersectionSPI Intersection

Tight DiamondTight Diamond

Sylvan Interchange Sylvan Interchange Tight Diamond Tight Diamond ConfigurationConfiguration

US 26 @ US 26 @ Scholls Ferry/SkylineScholls Ferry/Skylinein Portlandin Portland

Diverging DiamondDiverging Diamond

Contraflow LeftContraflow Left

Roundabout Ramp Roundabout Ramp IntersectionsIntersections

I-70 inI-70 inAvon, COAvon, CO

3-Level “Stacked” 3-Level “Stacked” DiamondDiamond

Lubbock, TXLubbock, TXUS 82/US 289US 82/US 289

Split InterchangesSplit Interchanges

Single Loop/Jug HandlesSingle Loop/Jug Handles

Greeley Ave @ Going St.Greeley Ave @ Going St.NE PortlandNE Portland

Single Loop/Jug Handle Single Loop/Jug Handle ExamplesExamples

Greeley Ave @ Going St. Greeley Ave @ Going St. (Portland)-☺(Portland)-☺

East End of Ross Isl. Br. East End of Ross Isl. Br. (Portland)- <☺(Portland)- <☺

OR 11 @ OR 204 (near Weston)OR 11 @ OR 204 (near Weston) US 97 @ Colorado Ave. (Bend)US 97 @ Colorado Ave. (Bend) OR 62 @ Biddle Rd. (Medford)OR 62 @ Biddle Rd. (Medford) OR 214 @ N. Front St. (Woodburn)OR 214 @ N. Front St. (Woodburn)

Grade Separated Grade Separated RoundaboutsRoundabouts

Uncommon in US – Ubiquitous in UKUncommon in US – Ubiquitous in UK

Intersection Grade Intersection Grade SeparationSeparation

Echelon InterchangeEchelon Interchange

Only known example – Only known example – US 1 @ Biscayne Blvd.US 1 @ Biscayne Blvd.in Aventura, Florida – near Miamiin Aventura, Florida – near Miami

Frontage Road SystemsFrontage Road Systems

Fairly common in Texas & some major Fairly common in Texas & some major Midwest cities – mostly on freeways – Midwest cities – mostly on freeways – both rural and urbanboth rural and urban

ODOT stuff tends to be connections or ODOT stuff tends to be connections or extensions of cut-off roadways, not extensions of cut-off roadways, not directly integrated to the mainline, directly integrated to the mainline, except for a few spots in Portlandexcept for a few spots in Portland

AASHTO Chapters 7 & 8 (Arterials & AASHTO Chapters 7 & 8 (Arterials & Freeways) have some discussions on Freeways) have some discussions on frontage systemsfrontage systems

Frontage ExamplesFrontage ExamplesI-35 in San Marcos, TXI-35 in San Marcos, TX

Frontage ExamplesFrontage Examples

Detroit, MI Detroit, MI Freeways – Incl. a Freeways – Incl. a wide variety of U-wide variety of U-turn provisionsturn provisions

Many Texas Many Texas Rural FreewaysRural Freeways

““Texas Texas Turnarounds” Turnarounds” another U-turn another U-turn variation.variation.

And Now Here’s Something And Now Here’s Something We Hope You’ll Really We Hope You’ll Really

Like… Like… The Diverging DiamondThe Diverging Diamond

Watch me pull a rabbit out of my hat.Watch me pull a rabbit out of my hat.

Fern Valley Interchange – I-Fern Valley Interchange – I-5 Exit 245 Exit 24

Image Stolen From Bob Branch’s Design – March 2010

I-44 @ SR 13 – I-44 @ SR 13 – Springfield, MOSpringfield, MO

Photos Courtesy of Don Saiko, MoDOT

First Completed DDI in the US – Opened to Traffic in Late June 2009 First Completed DDI in the US – Opened to Traffic in Late June 2009 (Before Construction was completed in July)(Before Construction was completed in July)

I-15 @ Main – American I-15 @ Main – American Fork, UTFork, UT

Photos from UDOT Project Website

Rendering of Final Product February 2010 Const. Photo

Currently Under Construction – North of OgdenCurrently Under Construction – North of Ogden

Diverging Diamond – The Diverging Diamond – The TradeoffsTradeoffs

Advantages include:Advantages include: Very effective in moving heavy LT demands - esp. compared to Very effective in moving heavy LT demands - esp. compared to

other diamond types – Two phase signals at intersections – Less other diamond types – Two phase signals at intersections – Less vehicle queuing.vehicle queuing.

Usually has a narrower X-Section on X-Road – extra LT lanes, Usually has a narrower X-Section on X-Road – extra LT lanes, etc. not needed – but the median area may be fairly wide anyway etc. not needed – but the median area may be fairly wide anyway (for other reasons).(for other reasons).

Probably will work for either Freeways or Arterials – assuming Probably will work for either Freeways or Arterials – assuming that downstream intersections don’t back up to the ramps.that downstream intersections don’t back up to the ramps.

DisadvantagesDisadvantages No “up and over” movement is possible at the ramp No “up and over” movement is possible at the ramp

intersections – U-turns necessary on X-Road.intersections – U-turns necessary on X-Road. When LT and Opposing thru movements are both very heavy, When LT and Opposing thru movements are both very heavy,

TPAU analysis has shown some operational issues that crop up.TPAU analysis has shown some operational issues that crop up. Extensive channelization, signing, markings are required for Extensive channelization, signing, markings are required for

the ramp intersections – the intersection geometry can be the ramp intersections – the intersection geometry can be tricky, esp. when the underlying roadway is in a horizontal tricky, esp. when the underlying roadway is in a horizontal curve. curve.

Access Management is just as necessary as with any other idea Access Management is just as necessary as with any other idea - Don’t overlook it!- Don’t overlook it!

QQ && aa

We’re ready for grilling.