I-49 Lafayette Connector Refinement Concept Plan Illustrations

8/18/2019 I-49 Lafayette Connector Refinement Concept Plan Illustrations

1/13

Key Features

Single Point Urban Interchanges (SPUI) at Johnston and 2nd/3rd Streets RR Crossing Grade Separations at Johnston, Jefferson, and 2nd/3rd Streets 2nd and 3rd Streets realigned to come together at single interchange

Johnston Street realigned to straighten curve and accommodate interchange ramps Portion of mainline I-49 on embankment between Johnston and 2nd/3rd Street interchanges

XAMPLES OF SIMILAR TRANSPORTATION FEATURES

levated Freeway Structure Single Point Urban Interchange(SPUI)

Urban Freeway on Embankme

REFINEMENT CONCEPT - 1ABase Case (I-49 Lafayette Connector Concept, preliminary engineering conceptrepresentation of FEIS Selected Alternative and ROD, 2003-2004)


2/13

Key Features

Replace Johnston and 2nd/3rd Street Downtown Single Point Urban Interchanges (SPUI) with TightUrban Diamond Interchanges (TUDI)

Maintain RR Crossing Grade Separations at Johnston and 2nd/3rd Streets

Maintain Jefferson Street RR Crossing Grade Separation 2nd and 3rd Streets realigned to come together at single interchange Johnston Street realigned to straighten curve and accomodate interchange ramps Portion of mainline I-49 on embankment between Johnston and 2nd/3rd Street interchanges

REFINEMENT CONCEPT - 1BBase Case (I-49 Lafayette Connector, 2003-2004) Modified


Tight Urban DiamondInterchange (TUDI)

Urban Freeway on Embankmentlevated Freeway Structure


3/13

Key Features

Remove 2nd/3rd Streets Downtown Interchange Change Johnston Street Downtown Interchange to Tight Urban Diamond Interchange (TUDI) Remove RR Crossing Grade Separation at 2nd/3rd Street

Maintain Jefferson Street RR Crossing Grade Separation Evangeline Thruway remains connected to overall frontage road system Portion of mainline I-49 on embankment between Johnston and 2nd/3rd Street interchanges


reeway on Embankment

REFINEMENT CONCEPT - 2ABase Case with Core Area Single Interchange – Johnston Street

Elevated Freeway Structure Tight Urban Diamond

Interchange (TUDI)


4/13

Key Features

Remove Johnston Street Downtown Interchange Change 2nd/3rd Street Downtown Interchange to Tight Urban Diamond Interchange (TUDI) Remove RR Crossing Grade Separation at Johnston Street/Louisiana Avenue

Maintain Jefferson Street RR Crossing Grade Separation Evangeline Thruway remains connected to overall frontage road system Portion of mainline I-49 on embankment between Johnston and 2nd/3rd Street interchanges

REFINEMENT CONCEPT - 2BBase Case with Core Area Single Interchange – 2nd/3rd Street


reeway on Embankment Elevated Freeway Structure Tight Urban Diamond

Interchange (TUDI)


5/13

Key Features

Change Johnston and 2nd/3rd Street Downtown Interchanges to function as a split diamondinterchange with connecting road system between half-diamonds:

– Johnston/Louisiana will be half-diamond to/from the south

– 2nd/3rd Streets will be half-diamond to/from the north Connecting roads between interchanges are at-grade and access controlled Maintain freeway on structure between Jefferson and Johnston Streets


plit Diamond Interchange with Connector Roads At-Grade Connector Road

REFINEMENT CONCEPT - 3ASplit Diamond Interchange with At-Grade Connector Roads

Elevated Freeway

Remove RR Crossing Grade Separations atJohnston and 2nd/3rd Streets

Maintain Jefferson Street RR CrossingGrade Separation

Evangeline Thruway remains connected tooverall frontage road system


6/13

Key Features



– 2nd/3rd Streets will be half-diamond to/from the north Connecting roads between interchanges are depressed in open trench Maintain freeway on structure between Jefferson and Johnston Streets


REFINEMENT CONCEPT - 3BSplit Diamond Interchange with Depressed Open Connector Roads

Maintain two (2nd/3rd and JohnstonStreets) RR Crossing Grade Separations

Elevate existing Jefferson Street RRCrossing Grade Separation (convert to at-grade) with Jefferson Street spanning overconnecting roads in trench


Elevated Freeway

plit Diamond Interchange with Connector Roads Connector Road in Open Trench


7/13

Key Features



– 2nd/3rd Streets will be half-diamond to/from the north Connecting roads between interchanges are depressed, in tunnel section Maintain freeway on structure between Jefferson and Johnston Streets


REFINEMENT CONCEPT - 3CSplit Diamond Interchange with Depressed Closed Connector Roads

Elevate existing Jefferson Street RRCrossing Grade Separation (convert to at-grade) with Jefferson Street spanning overconnecting roads in trench

Maintain two (2nd/3rd and JohnstonStreets) RR Crossing Grade Separations


plit Diamond Interchange with Connector Roads Connector Road in Tunnel

Elevated Freeway


8/13

Key Features

Remove Johnston and 2nd/3rd Street Downtown Interchanges Maintain 2nd and 3rd Streets (split) as part of Downtown Grid System Evangeline Thruway remains connected to overall frontage road system with ramp pairs to I-49

Lafayette Connector: – Maintains one-way couplet arterials between ramp pairs – Overall one-way couplet arterials, Johnston Street, 2nd Street and 3rd Street, developed as “Gra

Boulevard” concept with significant landscape and urban design improvements – Enhanced intersection treatments between Evangeline Thruway and Johnston, 2nd and 3rd

Streets (e.g., roundabouts) to create “gateway” entries to Downtown – Potential associated land acquisition program to create redevelopment area between and

adjacent to one-way couplet arterials Maintain freeway on structure between Jefferson and Johnston Streets Provide two additional (2nd and Johnston Streets) RR Crossing Grade Separations Maintain Jefferson Street RR Crossing Grade Separation


andscaped Arterial Parkway Ramp Pairs Multi-lane Roundabout

REFINEMENT CONCEPT - 4AEvangeline Thruway Connectivity System (with additional RR grade separation


9/13


10/13

Key Features

Remove Johnston and 2nd/3rd Street Downtown Interchanges Maintain 2nd and 3rd Streets (split) as part of Downtown Grid System Evangeline Thruway remains connected to overall frontage road system with ramp pairs to I-49

Lafayette Connector: – Becomes a paired two-way arterial connectivity system (4 lanes each) between ramp pairs – Overall Evangeline Thruway, Johnston Street, 2nd Street and 3rd Street, developed as “Grand

Boulevard” concept with significant landscape and urban design improvements – Enhanced intersection treatments between Evangeline Thruway and Johnston, 2nd and 3rd

Streets (e.g., roundabouts) to create “gateway” entries to Downtown – Potential associated land acquisition program to create redevelopment area between and

adjacent to paired arterials Maintain freeway on structure between Jefferson and Johnston Streets Remove RR Crossing Grade Separations at Johnston and 2nd Streets Maintain Jefferson Street RR Crossing Grade Separation

REFINEMENT CONCEPT - 4CEvangeline Thruway Paired Two-Way Connectivity System(without additional RR grade separations)


wo-Way Urban Arterial Ramp Pairs Urban Roundabout


11/13

Key Features

Remove Johnston and 2nd/3rd Street Downtown Interchanges Maintain 2nd and 3rd Streets (split) as part of Downtown Grid System Existing SB Evangeline Thruway becomes a two-way major arterial (4 or 6 lanes) connected to the

frontage road/ramp pair system from I-49 Existing SB Evangeline Thruway is developed as an “Urban Parkway” with median, and extensivelandscape and urban design improvements

Existing NB Evangeline Thruway is rebuilt as local street and is re-absorbed into neighborhood gridstreet system

Enhanced intersection treatments between Evangeline Parkway and Johnston, 2nd and 3rd Streets(e.g., roundabouts) to create “gateway” entries to Downtown

Maintain freeway on structure between Jefferson and Johnston Streets Remove RR Crossing Grade Separations at Johnston and 2nd Streets Maintain Jefferson Street RR Crossing Grade Separation

REFINEMENT CONCEPT - 4DEvangeline Parkway Connectivity System


wo-Way Urban Arterial Urban RoundaboutRamp Pairs


12/13

Key Features

Remove 2nd/3rd Street Downtown Interchange Change Johnston Street Downtown Interchange to Tight Urban Diamond Interchange (TUDI) Maintain 2nd and 3rd Streets (split) as part of Downtown Grid System

Return Evangeline Thruway to local street system, and develop parallel frontage roads throughoutDowntown area along I-49 Connector Enhanced intersection treatments between frontage roads and Johnston, 2nd and 3rd Street (e.g.,

roundabouts) to create “gateway” entries to Downtown Portion of mainline I-49 on embankment between Johnston and 2nd/3rd

Street interchanges Remove RR Crossing Grade Separation 2nd Street Maintain Jefferson Street and Johnston Street RR Crossing Grade Separations

REFINEMENT CONCEPT - 5AEvangeline Corridor Local Street System


levated Freeway Structure withontinuous Frontage Road

Tight Urban Diamond

Interchange (TUDI)

Urban Roundabout


13/13

KEY DESIGN FEATURESAPPLICABLE TO ALL REFINEMENT CONCEPTS

LEVATED FREEWAY STRUCTURE

IGNATURE BRIDGE

SES UNDER FREEWAY STRUCTURE

I-49 Lafayette Connector Refinement Concept Plan Illustrations

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