Innovative Transportation Solutions Melanie B. Young, P.E. District Transportation Operations Engineer Dallas District

Innovative Traffic Solutions

• Single Point Urban Interchange (SPUI)

• Median Lefts (Modified Michigan Lefts)

What is a SPUI?

• An intersection design that allows opposing left turns to proceed simultaneously by compressing the two intersections of a diamond into one single intersection over or under the free-flowing bypass road.

Advantages of a SPUI

• Improved operation, efficiency and safety.

• Reduced right-of-way.

• Allows for wider turns making it easier for larger vehicles to travel through the intersection.

• Allows simultaneous turning for the opposite left-turns.

SPUI Project Information

• US 75 at Parker Road in the City of Plano

• City of Plano submitted project for funding

• City managed Consultant PS&E design

• TxDOT let the project in April 2008

• Opened to traffic in December 2010

Interchange Characteristics

Pre-Construction

Four -jug handles with two way traffic and free right turns Heavy queues backing up on ramp and sometimes to frontage road In middle of coordinated signal system along Parker Rd. Queue from adjacent traffic signal extends past jug handles Frontage Road used as alternate to main lanes, 3 miles without signals, x ramp configuration with jug handles

Post Construction

Added traffic signal Separated out three frontage road movements Eliminated jug handles and yield conditions on 4 movements Added U-turn lanes for US 75 NB and SB Frontage road bypass for through movement underneath the SPUI structure Heavy frontage road through movement in the PM peak Significant overall reduction in delay

Pre-Construction

Simulation

Conceptual Drawing

Traffic Signal Phasing

• vsim

Bridge Layout

Opposing Left Turn Movements

Simultaneous Left Turn Movements

Parker Road Thru Traffic

Signing on frontage road approach

• http://www.youtube.com/v\8ZMKSlFrFDQ

Design Changes

Added chevrons to delineate island on up ramp from US 75 to SPUI.

Added lane assignment signs on Parker Road due to confusion on lane assignments.

Ramp from SPUI down to frontage road has limited sight distance. Frontage road lanes were reduced lanes to create a lane addition rather than a merge from the ramp.

Added one set of pedestrian signals.

Project Performance Increased traffic volumes for most of the turning

movements and through movements.

Significantly reduced delay, estimated at 50-75% reduction.

Improved safety.

Maintained existing signal cycle length for corridor.

Allows continuous flow of traffic along Parker Road.

Additional SPUI Project

US 75 at Eldorado Parkway in McKinney, let with freeway reconstruction project (let 3/11)

Currently a jug handle design.

Frontage Road bypass lane on the inside.

I

Median Left Turns (Modified Michigan Lefts)

What are Median Lefts?

• A design configuration to eliminate left turning vehicles from within the intersection with the intent to improve safety and improve traffic flow through the intersection.

Advantages of Median Lefts

Improved operation efficiency

Improved safety

Median Lefts Project Information

SH 289 (Preston Road) at Legacy in the City of Plano

Plano submitted project for funding

City managed Consultant PS&E design

Plano let the project in July 2009

Opened to traffic July 27, 2010

Interchange Characteristics

Pre- Construction

o Two -6 lane roadways

o Diamond interchange layout –designed for a grade separation

o Long traffic back-ups

o High traffic congestion and multiple cycle delay

o Existing Texas U’s on Preston Road

Post- Construction o Prohibits left turns from Legacy o Left turns allowed from Preston

Road o Built and signalized two U-turn

lanes on Preston Road o Increased green time for

through movements o Common that the queue will

clear in one cycle length

Advance Signing on Legacy

Signing at U turns

Design Changes

Reduced the number of lanes on the north U turn from 2 lanes to 1 lane.

Removed the restriction of NO TURN ON RED.

Project Performance • Reduced Back-up by 60%

• Reduced driver delay by 35 sec/veh

• Increasing drivers acceptance

• Working to increase compliance

• Increased citations

• Increased volumes

• Reduced turning traffic – alternate routes?

• City Council continuing to evaluate prior to proceeding with a similar design at two additional locations.

Safe Travels

Questions?