Calibration of SPFs in the HSM, IHSDM, and SafetyAnalyst - PowerPoint PPT Presentation

Loading...

PPT – Calibration of SPFs in the HSM, IHSDM, and SafetyAnalyst PowerPoint presentation | free to download - id: 6d3c08-NmViM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Calibration of SPFs in the HSM, IHSDM, and SafetyAnalyst

Description:

Calibration of SPFs in the HSM, IHSDM, and SafetyAnalyst Doug Harwood Midwest Research Institute Purpose of Calibration To enable SPFs or safety prediction methods ... – PowerPoint PPT presentation

Number of Views:0
Avg rating:3.0/5.0
Date added: 11 June 2019
Slides: 15
Provided by: Geni150
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Calibration of SPFs in the HSM, IHSDM, and SafetyAnalyst


1
Calibration of SPFs in the HSM, IHSDM, and
SafetyAnalyst
  • Doug Harwood
  • Midwest Research Institute

2
Purpose of Calibration
  • To enable SPFs or safety prediction methods
    developed with data from one jurisdiction to be
    applied in another jurisdiction

3
What Differences Between Jurisdictions Does
Calibration Account For?
  • Climate
  • Driver behavior
  • Animal populations
  • Crash reporting thresholds
  • Crash reporting system procedures

4
How is the Calibration Factor Used?
  • Typical SPF with Calibration Factor
  • N exp(a b x ln( AADT)) C

5
How is the Value of the Calibration Factor
Determined?
  • Steps in Calibration
  • Select facility types and SPFs
  • Select calibration sites
  • Obtain data
  • site characteristics
  • observed crash data
  • Apply SPF or predictive method to each site
  • Compute calibration factor

6
How is the Value of the Calibration Factor
Determined?
  • C Sum of observed crashes
  • Sum of predicted crashes

7
Calibration in SafetyAnalyst
  • The SPF for each individual facility type (i.e.,
    site subtype) is calibrated separately for each
    calendar year
  • All available sites for each site subtype of
    interest are used
  • Calibration is done automatically by the software
    whenever new data are loaded no user
    intervention is required

8
How is the Calibration Factor Used?
  • SafetyAnalyst SPF with calibration factor
  • N exp(a b x ln( AADT)) C

9
Data Needs for Calibration of SafetyAnalyst
  • Site characteristics
  • Crash frequencies
  • All needed data are mandatory variables in the
    SafetyAnalyst data set

10
Calibration in HSM Part C
  • The entire predictive method for a given facility
    type is calibrated, rather than individual SPFs

11
Calibration in HSM Part C
  • Calibration procedures are presented in the
    Appendix to Part C
  • Guidance is provided on
  • data elements needed for calibration (listed in
    Exhibit A-2 in Appendix to HSM Part C)
  • All input variables to HSM Part C methods are
    either required or desirable data
  • minimum samples sizes

12
Calibration in HSM Part C
  • A calibration data set must be assembled for each
    facility type
  • Minimum sample size for calibration
  • 30 to 50 sites that collectively experience at
    least 100 crashes per year
  • The same calibration sites can be used with new
    crash data (and updated traffic volumes) to
    calibrate for future years

13
Calibration in IHSDM
  • There is no formal calibration method built into
    the software
  • Calibration factors determined outside the
    software may be entered by the user
  • Calibration factors developed for the HSM or
    SafetyAnalyst can be used in IHSDM

14
Questions?
About PowerShow.com