I-17 and Happy Valley Road Diverging Diamond Interchange (DDI) Bharat Kandel (ADOT) and Jeremy Neuman (HDR) February 28, 2018
Project Purpose and Overview New interchange will accommodate current and future traffic projections and improve regional traffic flow and safety Construction Manager at Risk (CMAR) delivery method Contractor selected for pre-construction services (during design) Construction scheduled to begin in fall 2018 Current design and delivery schedule Approximately 20 months for construction
Happy Valley Road Existing Condition Spread diamond interchange 2-lane roundabouts with 1-lane in each direction within interchange area. Bridge is narrow and cannot accommodate future I-17 (5+1 lanes) expansion Does not accommodate bicyclist and pedestrians
Happy Valley Road New Construction Studied several interchange configurations DDI selected based on higher level of service, no design exceptions, fewer conflict points, pedestrian and bicycle treatment best value Remove Roundabouts 3 through lanes in each direction within Interchange area
New Construction New interchange accommodate future I-17 expansion (5+1 Lanes) DDI alignment improved construction phasing Constructing two TIs, both for design and construction (phasing), aesthetics and landscaping included, get in get out as a complete product CMAR so that the phasing and construction is seamless Construction Expertise CMAR delivery a good fit Contractor during the DDI design process
Design / Pre-construction Coordination with the City of Phoenix on: Aesthetics Crossroad impacts and restrictions Construction duration Project team collaboration on DDI as it is being designed Ensuring everyone is on the same page Fitting design elements in the design sidewalk, bicycle lanes, roadway signage Public Outreach, Communications ADOT Communications along with the design team Stakeholders, Residents, Businesses
Happy Valley Project History 30% Design 5 concepts evaluated Parclo selected as best performing Cost Risk Assessment Top Risks
Conventional DDI Benefits 2-phase signals Free flow lefts Fewer conflict points Difficult wrong way entry to ramps Shorter ped crossings BUT... not compatible with at-grade frontage roads
Rethinking the DDI as a Solution Happy Valley frontage roads volumes very low Spread diamond footprint provided ample space Developed a Modified DDI: Enhances Capacity Preserves 2-phase signal operation/progression Accommodates frontage roads Reduces cost and construction schedule Eliminates major ParClo risks
Modified DDI at Happy Valley Peak Traffic Patterns AM PM
Modified DDI at Happy Valley Frontage Roads
Modified DDI at Happy Valley MOT and Phasing
Happy Valley Signal Progression PH 1
Happy Valley Signal Progression PH 2
DDI - Signals & Signing
DDI Proven Performance with High Volume Traffic Generators
DDI - Safety Benefits Conflict Points 26 14 Points 102 Crossing
DDI - Safety Benefits Angled Crossings Decrease Severity of Crashes
DDI - Safety Benefits Wrong Way Movement Prevention
DDI - Safety Benefits Reduced Conflict Points Restrict Wrong Way Movement Ability Reduced Speed Through Intersections FHWA Study Results 50% Overall Collision Reduction / 60% Reduction in Fatal Collisions
DDI - Pedestrians Happy Valley Pedestrian Travel Route
DDI - Pedestrians Center Running in Median Protected Crossings Shorter Crossings
DDI - Cyclists Happy Valley Cyclist Travel Route
DDI - Cyclists Right Side of Vehicles Crossing at Intersections Shorter
Survey and Community Input Public meeting in July 2017 with 300+ attendees
Survey and Community Input Online survey in October 2017 Gather input on how ADOT could reduce impacts during construction More than 600 responses from residents, businesses, service providers One-on-one interviews with local businesses, service providers and large employers
Survey Results Were Positive Overall positive response for project by community members Primary concern: Maintain traffic flow during construction Maintain access to businesses, schools, shopping Minimize delays, especially during peak travel times
Construction Preference Fewer Impact/Longer Schedule More Impacts/Shorter Schedule No Opinion
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DDI - History & Existing Locations
DDI - Travel Patterns