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Use and Modification of Default SPFs in the IHSDM

Use and Modification of Default SPFs in the IHSDM. Mike Dimaiuta LENDIS Corporation. Options for using SPFs in IHSDM. Use Default SPFs “as is” Calibrate models, including SPFs Enter and use “your own” SPFs. Use Default SPFs “as is”.

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Use and Modification of Default SPFs in the IHSDM

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  1. Use and Modification of Default SPFs in the IHSDM Mike Dimaiuta LENDIS Corporation

  2. Options for using SPFs in IHSDM Use Default SPFs “as is” Calibrate models, including SPFs Enter and use “your own” SPFs

  3. Use Default SPFs “as is” Run IHSDM Crash Prediction Module (CPM) without calibrating (i.e. with calibration factors = 1.0)

  4. Use Default SPFs

  5. Use Default SPFs “as is”

  6. Calibrate Models / SPFs Follow HSM Part C calibration procedure and enter factors via IHSDM Administration Tool

  7. Calibrate Models / SPFs

  8. Calibrate Models / SPFs

  9. Calibrate model / SPFs

  10. Calibrate model / SPFs

  11. Enter and use “your own” SPFs Via the IHSDM Administration Tool: “Crash Prediction” > “Model Data Sets”

  12. Enter and use “your own” SPFs Capabilities: For all SPFs, can change: Regression coefficients Overdispersion parameters Limitation: Can not change SPF functional form

  13. Enter and use “your own” SPFs After editing data, save as a new Model Data Set “configuration” and select when running CPM

  14. Enter and use “your own” SPFs Example: Multilane Rural H’way Estimate crashes using defaults Enter “My State’s SPFs” into Administration Tool Run CPM with modified SPFs to generate and compare results

  15. Estimate crashes using default SPFs

  16. Enter “My State’s” SPFs into Administration Tool

  17. Enter “My State’s” SPFs into Administration Tool

  18. Enter “My State’s” SPFs into Administration Tool

  19. Run CPM with modified SPFs

  20. Compare Results Estimated Total crashes using default SPFs: 27.84 Estimated Total crashes using “My State’s” SPFs: 27.62

  21. Summary No requirement for agencies to develop their own SPFs for IHSDM, but… IHSDM provides a mechanism for agencies to edit all default SPFs (coefficients and overdispersion parameters only) Either way can produce good results!

  22. Questions? For additional information: www.tfhrc.gov/safety/ihsdm/ihsdm.htm IHSDM Technical Support: IHSDM.Support@fhwa.dot.gov; (202)-493-3407 To download IHSDM software: www.ihsdm.org Shyuan-Ren (Clayton) Chen Clayton.Chen@fhwa.dot.gov; (202)-493-3054

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