Calibration of HSM Freeways in Missouri Kyoungmin (Andrew) Nam, Mengyuan Zhang, Carlos Sun, Praveen Edara, and Henry Brown University of Missouri August 19, 2015 (Google, 2015)
Acknowledgements Mike Curtit, John Miller, Myrna Tucker, Drew Williford, Jen Harper, Bill Stone, and Ashley Reinkemeyer (MoDOT) US DOT University Transportation Centers Program Undergraduate and Graduate Research Assistants 2
HSM Freeways Overview 3 NCHRP 17-45 HSM Appendices Data from 3 states Washington California Maine Data sources Highway Safety Information System (HSIS) Aerial Photographs
4 HSM Predictive Method Number of Crashes = Number of Crashes for Base Conditions x Crash Modification Factors (CMFs) x Calibration Factor
5 Why Calibrate the HSM? Account for local conditions Driver behavior Topography Climate Crash reporting thresholds
6 How Do We Calculate Calibration Factor? Calibration Factor = OOOOOOOOOOOOOOOO CCCCCCCCCCCCC PPPPPPPPPPPPPPPPPP CCCCCCCCCCCCC
HSM Calibration Process Selection of Facility Types for Calibration Sampling Data Collection Review of Crash Reports Calibration 7
Freeway Facility Types 8
Selection of Freeway Segment Facility Types Rural/Urban No. of Freeway Lanes Rural 4 Urban 4 Urban 6 (Google, 2015) 9
10 Selection of Speed Change Lane Facility Types Rural/Urban Entrance/Exit No. of Freeway Lanes Rural Entrance 4 Urban Entrance 4 Urban Entrance 6 Rural Exit 4 Urban Exit 4 Urban Exit 6
11 Selection of Ramp Segment Facility Types Rural/Urban Entrance/Exit No. of Ramp Lanes Rural Entrance 1 Rural Exit 1 Urban Entrance 1 Urban Exit 1 Urban Entrance 2 Urban Exit 2
Example Interchange Configurations Parclo Diamond (Google, 2015) 12
13 Selection of Ramp Terminal Facility Types Configuration Traffic Control Rural/Urban No. of Crossroad Lanes Two Quadrant Parclo A (A2) Diamond 4-Leg (D4) Stop Rural n/a Stop Urban n/a Signalized Both 4 Stop Rural n/a Stop Urban n/a Signalized Both 2 Signalized Both 4 Signalized Urban 6 Cloverleaf n/a Both n/a
Sampling HSM Guidance Minimum 30 to 50 sites Total of at least 100 crashes/yr Approach Create database of interchange types Random sampling from each MoDOT District 14
Sampling 15
16 Calibration Scope Interchange Type Number of Interchanges Interchange Crashes Ramp Terminal Crashes A2 Stop - R 7 52 13 A2 Stop - U 9 205 33 D4 Stop - R 16 298 67 D4 Stop - U 15 447 109 D4 Signal -2 18 780 411 D4 Signal -4 18 1569 850 Totals 83 3351 1483
AADT Data Requirements Crash data (severity, number of vehicles) Distance to exit and entrance ramps Geometric data Horizontal curves Barrier lengths and offsets Lane and shoulder width Number of lanes Number of driveways and public road approaches (crossroad) Type of left turn phasing (crossroad) 17
Data Sources MoDOT Transportation Management Systems (TMS) Database Viewer for MoDOT Automated Road Analyzer (ARAN) Aerial and street view photographs CAD (horizontal curve data) Other MoDOT sources 18
Review of Crash Reports Errors found in coded crash location, such as: Unassigned crashes at ramp terminals Ramp terminal crashes incorrectly assigned to freeway Assign crash to correct facility type Exclusion of rare events Tutorial developed 19
Unassigned Crashes at Ramp Terminals (MoDOT) 20
21 Ramp Terminal Crashes Due to Queuing (MoDOT)
22 Physical vs. Functional Classification of Crashes: HSM Freeway segments, speed change lanes, and ramp segments: based on physical location
23 Physical vs. Functional Classification of Crashes: HSM Ramp terminals: based on both location and circumstances
24 Physical vs. Functional Classification of Crashes: Example 1
25 Physical vs. Functional Classification of Crashes: Example 2
26 Physical vs. Functional Classification of Crashes: Example 3
Calibration Tools IHSDM 27
Calibration Tools 28 ISATe spreadsheets
29 Calibration Results (Freeway Segments) Model Rural 4-Lane Urban 4-Lane Urban 6-Lane PDO Single Vehicle 1.51 1.62 0.88 PDO Multiple Vehicle 1.98 3.59 1.63 Fatal/Injury Single Vehicle 0.77 0.70 1.01 Fatal/Injury Multiple Vehicle 0.91 1.40 1.20
Conclusion Created database of interchange classification in Missouri Need for variety of data sources Use of CAD to estimate curve data Review of crash reports in progress Results obtained for freeway segments 30
31 Questions? E2509 Lafferre Hall Columbia, MO 65211 573-882-0832 brownhen@missouri.edu