“First In the Nation” Diverging Diamond Interchange IS 44 and MO 13 - Springfield, MO Joseph C Rickman, PE, ACTAR District Traffic Engineer MoDOT – Springfield Region

Kansas & I-44, 2008

Norton Rd. 681 ft’ Evergreen 296 ft’

Basic Interchange Problems  Congestion 15-30% left turns 10-15% HGV Closely spaced signals  Crashes  Pedestrian Accommodations

Congestion

Concept Design of the DDI

VISSIM Model

inVISION Studios Simulation

Opening Day – June 21 st, 2009

Opening Day Signal Timing  Interchange still under construction  Norton Rd Autoscope System failed  No Evergreen Rd signals due to construction  Time Travels run each plan throughout the day

Signal Timing  First in the nation  1 controller, dual ring configuration  Semi-compatible with Synchro  Offsets produced from travel times and VISSIM  Mostly seen as a 2 phase interchange  Timing set as a 4 phase operation Phase 2 Phase 4 Phase 6 Phase 8 Phase 6

Phase 1 - Northbound Phase 2 Phase 4 Phase 6 Phase 8 Phase

Phase 2 - Clear Phase 2 Phase 4 Phase 6 Phase 8 Phase

Phase 3 - Southbound Phase 2 Phase 4 Phase 6 Phase 8 Phase

Phase 4 - Clear Phase 2 Phase 4 Phase 6 Phase 8 Phase

Finishing the DDI  Islands installed  Pedestrian buttons added  Temporary signals moved from gores  Permanent advanced signals added in islands

July 7 th, 2009

Pedestrian Access

Project Timeline  Construction began: January 16 th, 2009  Lane restrictions on bridge: March 4 th, 2009  Traffic moved to DDI: June 21 st, 2009  Construction completed: July 7 th, 2009  Last modification: August 25 th, 2009  Final cost: $3.2 million

Operational Effects Superload on March 3, 2010

Operational Effects  Accidents Total Reduction 24% (50% between ramps) Injury Reduction 50%  Congestion removed on the bridge  Consultant Performance Evaluation (HDR)

Future Designs  Already planned for future interchanges Springfield, MO Kansas City, MO St. Louis, MO American Fork, Utah  Not the right choice for every problem High left turn volumes Modeling failed for Campbell & JRF Modeling is highly recommended

Public Perception  MoDOT survey of 8 zip codes  400 sent, 75 returned The Right Solution – 89.4% More Convenient – 95.1% Less Congested – 95.2% Safer – 96.7%

National Media “Looks pretty strange, but if it improves traffic flow, and safety, how can anyone complain?” “Kudos to MODOT for such a simple and elegant solution”

Questions? Joseph C Rickman, PE, ACTAR District Traffic Engineer