HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 HW 7: US 52 from Sageville to Holy Cross – Prediction of Safety Performance and Comparison to Actual Safety Performance Session #3 – Exercise I – US 52 in Iowa (west of DuBuque and the Mississippi River) – Prediction of Safety Peformance and Comparison to Substantive Safety Performance Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Learning Outcomes: Identify Crashes by type Apply models for safety performance to Level and On-Grade Tangent Segments Compare predicted crash frequency performance to actual safety performance Identify crash patterns that are over-represented Learning Objectives for Session #1 Introduction and Background for Intersection Safety Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 1996 - 2000 Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Crashes by severity Fatalities 2 Injuries – Major 3 Injuries – Minor 29 Injuries – Possible Injury 22 PDO 66 Total 122 Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop Collision Types HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Total: 122 Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop Segments/Grade/Curves August 2010 LOCATION NUMBER On Roadway Segments 63 Within Intersection 16 Intersection Related 1 On-Grades 3 On Curves 39 Total 122 Crashes by location Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 US 52 Geometric Plan information Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Geometric Information: Length: 13.0 miles AADT: 2,500 Lane Width: 11 feet Shoulders: Paved 0 feet Gravel 4 feet Hazard Rating: 5 Driveways: 91(on level tangent sections) Total Length of Curves = 4,826 ft or 0.914 mi Total Length of Grades = 13,400 ft or 2.54 mi US 52 Geometric Plan information Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Grade Section # % Grade Length in ft 1 5.6% 200 2 3.95 450 3 3.875 300 4 6 3200 5 5.2 7 700 8 5.4 350 9 3.05 400 10 900 11 5.9 1950 12 1700 13 1050 14 3.9 1150 15 4.8 150 Geometric Information: Grades: Total Length = 13,400 feet or 2.54 miles US 52 Geometric Plan information 3%< All Grades <6% Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 From the US 52 corridor crash information, perform the following: 1a: Identify crashes by type (Segment, Intersection, Curves) 1b: Compute the Severity Index (SI) for the 13 miles of US 52? SI = Fatal + Injury Crashes Total Crashes 1c: Is the Severity Index higher or lower than normal? Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Predict the Crash Performance for the following: SPF Base Model for US 52 Segment (level alignment), excludes grades and curves) SPF Base Model for US 52 Segment (on-grade segments only) Determine CMFs for Level Tangent and On-Grade Tangent Segments and apply the CMFs to the SPF Base Model Lane Width, Shoulders, Driveway Density, and Roadside Design Determine the Total Predicted Crashes for Level and On-Grade Segments Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Compare the predicted number of crashes per year for Level and On-Grade Tangent Segments with the Actual Safety Record and answer the following Question: “Is the actual crash frequency performance for the geometrics for US 52 for existing conditions less than the Predicted Crash Frequency?” Session 2 – Exercise I

HSM Practicitioner's Guide for Two-Lane Rural Highways Workshop August 2010 Identify crashes by type & Compute S.I. Compute Predicted Crashes for: Discussion SPF Base Model (Level Tangent Segments) SPF Base Model for On-Grade Tangent Segments SPF Base Model x CMF’s for both Segment above Total Predicted Crashes for both segments above Pause at this slide; continue on when participants have worked on the exercise. Is actual Safety performance better than predicted? Use Worksheet Exercise I Session 2 – Exercise I