Frequently Asked Questions

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This document is a list of frequently asked questions related to the IHSDM software. The document is applicable to the IHSDM 2019 Release software.



I'm new to IHSDM. How do I get started?

IHSDM is a suite of software analysis tools for evaluating safety and operational effects of geometric design on highways. The IHSDM - HSM Predictive Method 2019 Release includes six evaluation modules: Crash Prediction, Policy Review, Design Consistency, Intersection Review, Traffic Analysis and Driver/Vehicle Modules. The Crash Prediction Module (CPM) serves as a faithful implementation of Part C (Predictive Method) of the Highway Safety Manual (HSM) for rural two-lane highways (HSM Chapter 10), multilane rural highways (HSM Chapter 11), urban and suburban arterials (HSM Chapter 12), freeways (HSM Chapter 18) and ramps/interchanges (HSM Chapter 19). The Policy Review Module (PRM) is applicable to rural 2-lane and rural multilane highways. The other IHSDM evaluation modules are applicable to rural two-lane highways.

In addition, IHSDM includes an Economic Analyses Tool (EA Tool), which allows users to conduct economic analyses within IHSDM, using Crash Prediction Module evaluation results (crash frequencies and severities). IHSDM Economic Analyses Tool Help and an IHSDM Economic Analyses Tool Tutorial Lesson are available to help you get started.

For a general overview of IHSDM, the best starting point is the main IHSDM web site,

I have the IHSDM 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010 or 2008 Public Release and/or the IHSDM 2009 CPM Beta Release. Can I install the IHSDM-HSM Predictive Method 2019 Release over my old installation?

You can install the IHSDM 2019 Release (version 15.0.0; October 2019) over 2011 and later versions of IHSDM. You should not install the IHSDM 2019 Release over versions from before 2011. To access your 2010/2009/2008 Release Projects, first Archive the Projects in the old Release, and then Un-Archive the Projects in the 2019 Release.

I've downloaded IHSDM, now what?

IHSDM is packaged as a Windows installer archive. Start the installation process by launching the distribution package application, e.g., the downloaded file named ihsdm_15_0_0_full.exe. After the installation process is completed, a series of dialogs will ask a series of questions related to the installation.

I've installed the IHSDM-HSM Predictive Method 2019 Release. As a new user how should I start?

After successfully installing the IHSDM we suggest that you start by reviewing the IHSDM Tutorial (under "Help" in the main menu).

I've installed the IHSDM-HSM Predictive Method 2019 Release. As a previous user of the IHSDM how should I start?

Start IHSDM, open the Help Browser (from the main menu "Help/ Help Browser") and read through the "Release Notes for 2019 Public Release."

You may install the 2019 Release over the 2018 Release Update, 2018 Release, 2017 Release Update, 2017 Release, 2016 Release Update, 2016 Release, 2015 Release Update, 2015 Release, 2014 Release Update, 2014 Release, 2013 Release, 2012 Release or 2011 Release. You can archive your 2010/2009/2008 Release projects individually (via Project Operations > Archive Project), then un-archive them in the 2019 Release (via User Operations > Un-archive Project).

I have the IHSDM 2006 or 2004 Release. Can I install the 2019 Release over my old installation?

If you wish to upgrade from the 2006 or 2004 Release to the 2019 Release, we suggest that you contact IHSDM Support for assistance at or (202)-493-3407.

When is the next version of IHSDM anticipated?

The next Public Release of IHSDM (2019 Release Update) is likely to be in the spring of 2020.

How do I get technical support for IHSDM?

The technical support email address is:

The technical support phone number is: (202) 493-3407.

Is formal training available for IHSDM?

Yes, as noted here.

Is IHSDM available for the (insert your favorite) operating system?

Currently, IHSDM is available for the recent various flavors of the Microsoft Windows operating system. The supported versions of Windows Intel IA32 include:

  • Windows 10
  • Windows 7

Supported versions of Windows x64 include

  • Windows 10
  • Windows 7

Most IHSDM development and testing is done in a x64 and IA32 Windows 10 environments.

Note: The software development team has not tested IHSDM version 15.0.0 on Windows 8, but our expectation is that it will run successfully.

IHSDM is implemented in the Java programming language, and in theory, is portable to operating systems supporting a Java 8 virtual machine (for example). Some testing of IHSDM has been done on Linux using the Sun Linux Java Runtime Environment, however we are not packaging a distribution of IHSDM for Linux or any other operating system because of a lack of demand. For more information, see this.

Is there a way to interface my highway design software to IHSDM?

IHSDM can import LandXML format data (Schema 1.0). Many civil engineering design software packages also support LandXML and can export data into this format. A list of such software packages is available on the LandXML web site ( In addition, the GEOPAK-to-IHSDM Data Extraction tool (an MDL application) is distributed with IHSDM; the tool works with GEOPAK 98, 2000, and 2001.

IHSDM and the Highway Safety Manual

What is the relationship between the IHSDM - HSM Predictive Method 2019 Release and AASHTO's Highway Safety Manual?

The Highway Safety Manual (HSM) was developed by the Transportation Research Board and AASHTO, with AASHTO publishing the 1st Edition HSM in June 2010. The HSM contains four parts (A, B, C and D). Part C (Predictive Method) documents Crash Prediction Methodologies for three types of highways: rural two-lane highways, multilane rural highways and urban/suburban arterials. In addition, the HSM 2014 Supplement contains Predictive Methods for Freeways and Ramps (HSM Chapters 18 and 19, respectively). The IHSDM Crash Prediction Module (CPM) is intended to be - to the extent possible - a faithful software implementation of the crash prediction methods documented in Part C of the HSM.

The 2016 Release expanded the IHSDM Crash Prediction Module (CPM) by implementing draft Highway Safety Manual (HSM) crash predictive methods for 6+ lane and 1-way urban/suburban arterials, developed under NCHRP Project 17-58. The 2019 Release expanded the CPM further by implementing crash prediction methods for roundabouts, based on methods developed under NCHRP Project 17-70 and documented in NCHRP Research Report 888 (Development of Roundabout Crash Prediction Models and Methods). These new predictive methods are expected to be incorporated into the future 2nd Edition HSM.

For more information on the Highway Safety Manual, visit the HSM public website at

Why use IHSDM to apply HSM Part C Predictive Methods?

IHSDM offers many advantages for users wishing to implement HSM Part C methods, including:

  • IHSDM can evaluate many highway segments, intersections and interchanges over a number of years
  • “Location-Based” Data Input, which automatically segments the highway into homogeneous segments as per HSM Part C. Data can be entered in stations or mileposts.
  • “Site-Based” Data Input, which is especially useful for projects where detailed, location-based geometry is not available
  • The IHSDM CPM is intended as a faithful implementation of the entire HSM Part C. So… For Freeway / Interchange projects that impact non-freeway highways, users can apply HSM Part C methods to other network components (e.g., cross-roads, connectors, local roads & intersections)
  • IHSDM can handle complex (and simple) alignments
  • IHSDM seamlessly evaluates a highway that changes facility type (e.g., rural 2-lane to rural multilane)
  • IHSDM implements the Empirical-Bayes (EB) procedure
  • The IHSDM “Navigation tree” helps users to organize projects, highways, evaluations, etc.
  • IHSDM Evaluation Reports and Graphs provide extensive documentation of results / output
  • The IHSDM Highway Viewer provides graphical representation of the design
  • Extensive documentation is available via the IHSDM “Help Browser”
  • A Tutorial provides step-by-step “soup to nuts” guidance
  • The IHSDM System Administration Tool (AdminTool) includes a Calibration Utility to help agencies implement HSM Calibration Procedures

In addition, IHSDM now includes an Economic Analyses Tool, which allows users to conduct economic analyses within IHSDM, using Crash Prediction Module evaluation results (crash frequencies and severities). IHSDM Economic Analyses Tool Help and an IHSDM Economic Analyses Tool Tutorial Lesson are available to help you get started.

My agency wants to calibrate Highway Safety Manual Part C crash prediction models. Can IHSDM assist this effort?

Yes! A Calibration Utility is in the IHSDM Administration Tool (Admin Tool), to assist agencies in implementing the calibration procedures described in the Appendix to Part C of AASHTO’s Highway Safety Manual (HSM).

The Crash Prediction panel of the Administration Tool contains three sections:

  • Calibration Data Sets
  • Crash Distribution Data Sets
  • Model Data Sets

The Calibration Data Sets interface provides a mechanism for users to enter, edit and organize the site data to be used to calculate the calibration factors for the various crash prediction models available in the IHSDM Crash Prediction Module (and, thus, in HSM Part C). In addition to containing the user-entered site data, each Calibration Data Set is also linked to a Crash Distribution Data Set and a Model Data Set.

Within the Calibration Data Set interface, the user can choose to either Calibrate Using Site Data or Manually Specify a Calibration Factor for each of 57 crash prediction models covering rural two-lane highways, rural multilane highways, urban/suburban arterials, freeway segments, and freeway ramps/interchanges (ramps, C-D roads and ramp terminals).

When running a Crash Prediction Module (CPM) evaluation, the user indicates which Calibration Data Set to use in that particular evaluation. The CPM then applies the appropriate calibration factors from the user-selected Calibration Data Set.

Tutorial Lesson 10 (CPM Calibration) provides step-by-step instructions and hands-on exercises related to the calibration process.

IHSDM Policy Review Module

Which AASHTO policies are available for IHSDM?

The IHSDM Policy Review Module references the 1990, 1994, 2001, 2004 and 2011 editions of AASHTO's A Policy on Geometric Design of Highways and Streets, for policy checks on rural two-lane highways; and the 2004 and 2011 editions for policy checks on rural multilane highways.

Is there a way to add my organization's design policies to IHSDM?

Yes. The IHSDM Administration Tool (admintool.exe) includes the capability to edit values in currently available AASHTO policy tables to reflect other organizations' design policies. A limitation is that it is not possible to alter the column structure of the policy tables.

IHSDM Data Structure

Where can I find information on how projects, highways, intersections, Site Sets and evaluations are related?

For detailed information on how projects, highways, intersections, Site Sets and evaluations are related, refer to the "IHSDM Interface and Data Organization" section of the IHSDM documentation (Help > Help Browser).

Are sample projects provided with the IHSDM software?

The Tutorial folder of the IHSDM software contains over 20 sample archived Projects. These Projects are referenced in various Tutorial exercises, but can also be used apart from the Tutorial for users to become familiar with aspects of IHSDM Projects. Sample Projects include:

  • IHSDM Pike: three projects related to the 2.7 mile long IHSDM Pike are available – one with IHSDM Pike as a rural 2-lane highway (IHSDM Pike Project), one as a rural multilane highway (IHSDM Pike-Rural Multilane), and one as an urban arterial (IHSDM Pike-Urban Arterial).
  • Example Project 1 – Tutorial Lesson 9: a version of IHSDM Pike used in Tutorial Lesson 9 on Output / Reporting.
  • Example Freeway: An "Example Freeway" highway network that contains a 6-lane freeway segment with 2 crossroads and 2 interchanges, including C-D roads, ramps and ramp terminals.
  • Example Freeway-Economic Analysis: A version of the "Example Freeway" project (see above), containing an existing highway network and two alternative cases. IHSDM Tutorial Lesson 11 (Economic Analyses Tool) uses this project as a case study.
  • HSM Chapter 18 Sample Problems: 5 Projects related to HSM Chapter 18 Sample Problems (SP) 1-5 for Freeway Segments (HSM Ch 18 SP1, HSM Ch 18 SP2, HSM Ch 18 SP3, HSM Ch 18 SP4, and HSM Ch 18 SP5).
  • HSM Chapter 19 Sample Problems: 6 Projects related to HSM Chapter 19 Sample Problems (SP) 1-6 for Freeway Ramps/Interchanges (HSM Ch19 SP1, HSM Ch 19 – Sample Problem 2, Entrance Ramp - HSM Ch 19 SP3, Ramp Terminals-Ch19 SP4, A4 Ramp Terminal 1-Way_Stop HSM Ch 19 SP5, and B2 Ramp Terminal AWSC_HSM Ch 19 SP6).
  • Siteset-Rural Multilane: a sample Site Set, containing data for Four-Lane Undivided Segments, Four-Lane Divided Segments, Three-Legged Minor-Road Stop Control Intersections, Four-Legged Minor-Road Stop Control Intersections, and Four-Legged Signalized Intersections. This Site Set is used in Tutorial Lesson 4 (Crash Prediction Module).
  • Pennsylvania I-70 Case Study: three projects related to an interchange alternatives analysis case study, including projects for the two alternatives evaluated (Alternatives 2A and 3), and a "training" version of the Alternative 2A project. These projects are used in Tutorial Lesson 4, Exercise 4.9.
  • Roundabout Exercises: two projects are used in Tutorial exercises related to the roundabout crash prediction method.

Graphical User Interface

Is there an alternative to using edit dialogs for list boxes?

The user can customize how list boxes function by setting the options found on the Review/Edit GUI Preferences accessed through the Edit/Preferences Controls menu item.

Is there a way to use the Firefox/Mozilla/Netscape/Internet Explorer HTML browser?

The user can select any installed HTML browser by using the HTML browser file chooser on the Ancillary Programs tab of the Review/Edit GUI Preferences dialog accessed through the Edit/Preferences main menu item.

Installation Options

Are there options for a "silent" installation of IHSDM or for a target directory installation?

Yes. There are installation switches for silent and target directory installations. Text is provided on the installer page and in the Help to provide details of using the following switches:

  • /S runs the installer silently
  • /D= sets the default installation directory. It must be the last parameter used in the command line and must not contain any quotes, even if the path contains spaces. Only absolute paths are supported.

For example, a command line similar to the following should install IHSDM to the designated path without prompting: C:\>ihsdm_15_0_0_full.exe /S /D=c:\IHSDM2019