2015 MDOT / ACEC Partnering Workshop Diverging Diamond Interchanges in Michigan Lori Swanson MDOT Oakland TSC John Katers OHM Advisors Chris Van Norwick MDOT Grand Region Rob Leppala TranSystems
Topics National Trends, Advantages and Challenges Missouri DOT and MDOT Collaboration I-75 / University Drive DDI I-96 / Cascade Road DDI
DDI Features Traffic crosses to opposite side over the bridge No opposing left turns or loop ramps 2-phase signal Free-flow onramps
DDIs in the U.S. France: 1970s Missouri: 2009 >40 in US: 2010-14 2 in MI: 2015-16
2014 FHWA DDI Guide Planning and design guidance Some safety research data Observed trends and design principles
Design Principles Clear guidance and vehicle path alignment Reduced and consistent speeds Accommodate trucks
DDI Advantages and Challenges
Safety Advantages Reduced # of conflict points Low speeds No left turns
Safety Challenges Wrong-way maneuvers: more likely at off-peak times and lower ADTs Sight distance at exit ramps: No Turn on Red Unfamiliarity: Signal compliance and lane changing
Operational Advantages 2-Phase signals improve traffic flow Left turn movement pass thru 1 signal Reduced delay
Operational Challenges Nearby signalized intersections Signal coordination in both directions Lower capacity where RTOR is not allowed
Non-Motorized Advantages Cross onedirection at a time Short crossing distances Low speeds
Non-Motorized Challenges Peds might need to cross un-signalized intersection Peds unaware where traffic is coming from
Other Advantages Reduced ROW costs Retrofit existing interchanges Traffic calming
Other Challenges Does not allow exit to entrance ramp movement Lighting and overhead signing Dramatic speed reduction for some arterials
Lessons Learned The Missouri Experience Operations Before and After Traffic Models Reflect Actual Conditions Pedestrians Adapting Crash Analysis Before and After Public Involvement Signs, Signals and Pavement Markings
Operation Before and After MoDOT had favorable results Safety Improved Capacity Improved Traffic Models Reflect Actual Conditions Models were Calibrated to Local Conditions Actual Conditions were Being Reflected Phasing Design was Difficult Due to Pedestrian Interruptions
Pedestrian Use Difficulties with Pedestrians Having to Look in Contrary Direction Pedestrians Crossing Free Flow Ramps Sight Distance Pedestrian Fencing and Alignment of Walkway
Crash Analysis for DDI MoDOT Experience Average of 40% Reduction in Crashes 80% Reduction in Injury Crashes Due to Less Conflict Points Increased Capacity and Less Queuing
Public Involvement Meetings with Key Stakeholders Press Coverage YouTube Videos Public Meetings
Signs and Signals Signs: Sign Schemes with Directional Diagrams Overhead Signs Rather Than Ground Mounts Signals: Timings are Critical MoDOT Recommends Using Half Cycle Lengths to Accommodate Random Nature of Freeway Traffic Left Turns on Red are Restricted by MoDOT
Pavement Markings Pavement Markings: Unique Pavement Markings Such as Route Shields and Pedestrian Markings Look Right Directional Arrows
Changes Considered in MDOT Design Wide Shoulder Width Safety; Easier to Achieve Proper Crossing Angle Simplify Future Maintenance of Traffic Balance Driver Information; Avoid Information Overload Avoid Queue Spillback at Nearby Intersections Nearby Intersections Being Flooded by DDI Traffic
I-75 at University Drive Location: Auburn Hills, Oakland County, MI Owners: Preliminary Design: OHM Advisors Final Design: Design-Builder
I-75 / University Drive OAKLAND UNIVERSITY PALACE OF AUBURN HILLS DDI CHRYSLER WORLD HQ
I-75 / University Drive 1960s
I-75 / University Drive 90s-2000s: Chrysler interchange and more!
I-75 / University Drive Chrysler interchange < 1 mile from University Dr NB C-D ROAD ENDS
I-75 / University Drive Proposed Parclo Upgrade (1998-2004): Cost ROW Impacts
I-75 / University Drive Parclo upgrade cancelled -Auburn Hills frustrated Operational issues remain Poor physical condition Front door is dilapidated
I-75 / University Drive
I-75 / University Drive
I-75 / University Drive
I-75 / University Drive Auburn Hills authorized study of interchange alternatives - 2008 Parclo Roundabouts SPUI DDI ted DDI to MDOT in late 2008
I-75 / University Drive 2009-2013: 5 unsuccessful TIGER Grant applications 2013: University Dr rehabilitation design Jan 2014: beams fractured; bridge shut down Jan / Feb 2014: funding started coming together March 2014: Preliminary design on DDI begins
Operations and Geometric Design Traffic Counts & Growth Projections Utilities Right-of-Way Soils, Wetlands, and Drainage Maintenance of Traffic Stakeholder / Public Concerns Preliminary Geometry
Operations and Geometric Design
Operations and Geometric Design Synchro: Model the Signal Network LOS C or better (2040) at crossings Opdyke Rd & Pontiac Rd HCS: Ramp Weave/Merge/Diverge Analysis LOS D or better (2040) Chrysler Interchange
Operations and Geometric Design Geometrics: Speed reduction Vehicle path alignment Trucks
Operations and Geometric Design
Operations and Geometric Design Crossover location critical Vehicle path Trucks Pedestrians Ramp geometry
Operations and Geometric Design
Operations and Geometric Design 2-thru lanes exist: 4-thru lanes proposed:
Operations and Geometric Design
Operations and Geometric Design Existing (looking north): C-D NOT CONNECTED TO I-75 Proposed: CONNECT C-D TO I-75
Operations and Geometric Design Crossover location critical Vehicle path Trucks Pedestrians Ramp geometry
Operations and Geometric Design Operational issues & trucks Wetland ROW: only 2 parcels total, 1 permanent!
Non-Motorized OLD: SIDEWALK GAP NEW: CONNECTIVITY!
Non-Motorized Crossing locations Center of bridge?!?! Barrier and lights
An iconic gateway Economic growth Aesthetics
Aesthetics An Identity Beyond an Exit Number
Project Status Design (by Design-Build Team): Now Begin Construction: Early 2015 Complete Construction / Open to Traffic: Late 2015
I-96 at Cascade Road Diverging Diamond Interchange Chris Van Norwick, PE Rob Leppala, PE
Agenda Existing Conditions The DDI Two-Bridge Concept and Critical Geometrics Design and Operational Features Operational Performance DDI Benefits Questions
Existing Parclo Interchange
Existing bridge constructed in 1961 Deteriorated deck and substructure Existing bridge on spread footings Deck carries 4 lanes plus ramp tapers On horizontal curve with super Existing Bridge
Existing Loop Ramp Geometrics Substandard ramp deceleration length from I-96 Substandard ramp acceleration length onto Cascade Rd 230 ft radii (30 mph Design Speed)
Existing Traffic Patterns (AM-Peak)
Existing Traffic Patterns (AM-Peak) Left-turn queue at East Paris Ave spills back into the interchange; limited dual left turn storage Cascade Road (looking west)
Existing Traffic Patterns (AM-Peak) Unbalanced Lane Use EB I-96 Exit Ramp to WB Cascade Road (looking east)
Existing Traffic Patterns (PM-Peak)
Existing Traffic Patterns (PM-Peak) WB I-96 Mainline Congestion (PM-Peak) Domino Effect WB I-96 Entrance Ramp Congestion Spillover onto Cascade Road Spillback into East Paris Avenue Westbound I-96 (looking west)
Existing Traffic Patterns (PM-Peak) Left-turn queue to enter WB I-96 spills back to East Paris Avenue Cascade Road (looking east)
Summary of Existing Interchange Concerns Existing Bridge Condition Loop Ramp Geometrics Traffic Congestion WB I-96 Mainline WB Entrance Ramp (Lack of gaps) East Paris Avenue Unbalanced Lane Use Lack of Pedestrian Accommodations
Alternatives Analysis Due to bridge and traffic operational issues a study was undertaken to investigate interchange modifications The study analyzed the following options: No Build Parclo interchange Diverging Diamond Interchange Initial DDI Concept was developed DDI geometry was refined through iterative process of traffic and geometric analysis
DDI Two-Bridge Concept
DDI Two-Bridge Concept
NO LEFT TURNS DDI Two-Bridge Concept
DDI Two-Bridge Concept NO LEFT TURNS LANE BALANCE AND CONTINUITY
DDI Two-Bridge Concept LANE BALANCE NO LEFT TURNS LANE BALANCE AND CONTINUITY
DDI Two-Bridge Concept LANE BALANCE NO LEFT TURNS LANE BALANCE AND CONTINUITY PEDESTRIAN FACILITIES
DDI Two-Bridge Concept LANE BALANCE NO LEFT TURNS LANE BALANCE AND CONTINUITY PEDESTRIAN FACILITIES SHOULDERS
DDI Two-Bridge Concept LANE BALANCE NO LEFT TURNS LANE BALANCE AND CONTINUITY PEDESTRIAN FACILITIES SHOULDERS LIGHTING
DDI Crossover Geometrics FEATURE MoDOT RECOMMENDED I-96 / CASCADE Skew Angle CROSSOVER SKEW ANGLE 40 o TO 50 o 45 o APPROACH TANGENTS 15 20 FT 12 38 FT DEPARTING TANGENTS 10 15 FT 12 36 FT INNER CURVE RADII 150 300 FT 150 625 FT LANE WIDTHS 15 FT 15 FT
Design and Operational Features 2-phase signals at crossovers and ramps 90-second cycle length Eastbound Cascade Road Phase
Design and Operational Features 2-phase signals at crossovers and ramps 90-second cycle length Westbound Cascade Road Phase
Other Design and Operational Features All Interchange Turning movements designed for WB-67 EB I-96 exit ramp upgraded to two-lane exit with option lane per MDOT GEO-140-B Case II Minor ROW impacts in NW and SE Quadrants for sidewalk and grading Utility Relocations including AT&T conduit bank, DTE gas main, and Consumers Energy overhead electric
Design and Operational Features Overhead Signing Concept with Lane Assignments Arrows
Video Animation of Proposed Design
Future-Year (2035) Level-of-Service Comparison VISSIM Modeling Results Movement Cascade W Pkwy SB Left East Paris Ave NB Right East Paris Ave WB Left I-96 EB Exit Ramp SB Right I-96 WB Ent Ramp EB Left I-96 WB Exit Ramp NB Right Peak Hr No Build DDI Delay (sec) LOS Delay (sec) LOS PM 92.7 F 44.1 D PM 75.8 E 14.1 B AM 27.5 C 17.7 B AM 58.0 E 21.9 C PM 49.8 E N/A Free flow AM 57.6 F 25.8 C
Cascade Road DDI Benefits Eliminates slow-speed exit loop ramps Provides improved lane balance on EB I-96 exit ramp and westbound Cascade Rd Improved LOS/delay reduction in Cascade Rd peak hour left turn movements to fwy entrance ramps Construction staging benefits (southern bridge offline from existing; no part-width bridge construction)
Project Schedule and Cost Project Schedule Final Plans: Spring 2015 Letting: July 2015 Construct Southern Bridge: Fall 2015 Complete Interchange: 2016 Project Cost Prelim Construction Cost Estimate = $12.6 M
Questions