AASHTOWare Safety Alternative Design enables designers, planners, and safety engineers to run Part C calculations found in the Highway Safety Manual.

Alternative Design calculates the safety improvements made by designers, planners, and safety engineers through changes made to roadway characteristics including lighting, shoulder size, lane width, etc. The AASHTOWare Safety Alternative Design application produces reports that compare multiple proposals on metrics such as crash reductions and benefit-cost ratios.

The Alternative Design application includes four modules and includes Empirical Bayes calculations for each of the modules:

Alternative Design will receive ongoing updates for newly developed calculations, including the forthcoming Highway Safety Manual Version 2 Part C, which includes bike and pedestrian modules.

For more information regarding Alternative Design, including key terms used in this article, see the Alternative Design - Key Terms article.

Alternative Design is broken into multiple sections, each of which is discussed in more detail below:

The Project Selection section is where you select the segment, or intersection, that will be the focus of your project. To help select routes, users can use map features such as asset layers, which allow users to overlay various characteristics on the map.

(Asset layer displaying city boundaries on the map)

By clicking the +Add Segment button, you can add a segment to the project. After clicking the button, you will be prompted to select the endpoints on the desired segment from the map.

(Selecting a Segment to include in the project)

After selecting the segment, it will be added to the current project and displayed in the segment summary on the right side of the screen.

Users can also add a related segment. When this option is selected, the “Add Related Segment” pop-up box appears with four available options:

(Add Related Segment pop-up box)

Intersections are defined by the user for each project and can be added by clicking the +Add Intersection button. Begin selecting one of the legs of the intersection by clicking on the two endpoints for the first leg of the intersection. After selecting the first leg, you can add each additional leg of the intersection by clicking the +Add Intersection Leg button under the indicated intersection. The intersection leg limit is eight legs.

(Adding a leg to the intersection)

After all Segments and Intersections have been added to the project, click the blue Continue button to proceed to the Current Condition tab of the design project.

Users can create a road segment within an Alternative Design project. Select “New Proposed Segment” and draw at least two points on the map to generate the new road.

Once the points are selected, click “Done,” and the new segment will appear as a dashed line on the map. Users can adjust the length of proposed segments by clicking into the length textbox and entering a new value.

(The newly created segment is displayed as a dashed line on the map.)

To differentiate between segments and intersections on the map, users can add labels and shapes. Use the “Draw Rectangle” or “Draw Circle” feature from the map toolbar to draw shapes on the map.

To add labels for segments and intersections, click the stacked dots to the right of the added segment/intersection and select “Add map label.” Once you click “Add map label,” choose the point on the map where you’d like the label to be added. The label will automatically use the name assigned to that segment or intersection. If users keep the default names (e.g., “Segment 1”), those default names will appear in the map labels. To edit the label's placement, repeat this process and select a different placement point on the map.

(Add Map Label option)

Click continue or select “Current Condition” from the top menu bar to input additional information about the segment.

The current condition tab is where you define the current state of the roadways involved in your project. You will need to populate the roadway information and details for each Segment and Intersection included in your project. This is done by filling out each field listed under each Segment or Intersection listed in the left sidebar of the screen.

Under the Segment or Intersection Information section, you can name each Segment or Intersection and define the Roadway Type, and volume information for the selected roadway. Note that the AADT information will be populated automatically for the selected Segment/Intersection.

(The Segment Information Tab for the selected segment, with the Roadway Type, and AADT fields populated)

(The Intersection Information Tab for the selected Intersection with the roadway type, intersection type, and AADT fields populated)

The Roadway Details section will require you to populate roadway characteristics for each of the Segments and Intersections selected. The fields will change depending on the selected roadway or intersection type.

(The Roadway Details section of a given Segment)

On this page, users can input a custom CMF using the + Custom CMF button. This enables users to enter a custom CMF or, for those with the Safety Analysis application, choose a state-provided CMF from a drop-down list.

(The +Add CMF button)

(Customers with Safety Analysis have the option to add state-provided CMFs in Alternative Design)

At the bottom of the Roadway Details page, users can use the copy option to duplicate the roadway details to other segments or intersections in the project.

The Bike and Pedestrian Details sections will require you to select any relevant roadway characteristics for each of the Segments and Intersections selected. The fields will change depending on the selected roadway or intersection type. (Note: This section is currently undergoing changes to align with the upcoming release of the Highway Safety Manual Second Edition.)

The Crashes section summarizes historical crash data populated from the selected segment(s) and intersection(s). To explore the crashes in a location, click the Open in Crash Query button; a new tab will open to display the selected location and all associated crashes.

(The Crashes section of a given Segment)

The No-Build tab contains several variables that must be defined to complete your project. This includes AADT growth, cost of the no-build project, and any notes associated with the no-build scenario.

(The No-Build section of a given project)

Users can enter notes about the no-build proposal in this section with a 5,000-character maximum limit.

The Analysis Method section allows users to choose which analysis method (Expected or Predicted) to apply to the segment(s) and/or intersection(s) proposals in the project. The selected analysis method will be used to generate the calculations displayed in the Summary and Comparison Summary sections.

Users can apply the chosen analysis method to all segments/intersections in the project, or choose different analysis methods for each segment and intersection.

The “Crashes by Analysis Method” chart shows the observed, predicted, and expected number of crashes for each segment or intersection. The selected analysis method is highlighted on the chart with a black outline. The table below the chart presents the same information in tabular form.

Under the Options section of the No-Build tab, users can input the following information: growth rate and cost.

The Summary section under the No Build tab shows the total number of crashes (either expected or predicted, depending on the selected analysis method), calculated over a 10-year period for the No-Build scenario. These results are generated using the segment and intersection details defined earlier in the Current Condition tab.

(The Summary section for a project)

The Proposals tab allows you to add multiple proposed changes to each location in your project. These projects will be compared to the current condition and are required in order to complete a comparison summary. While at least one proposal should be included for each project, multiple proposals can be added. Each additional proposal will be included in the Comparison Summary section of the project.

To add a new proposal to a project, click the +Add Proposal button in the top right corner of the project screen. You can populate your new proposal with current roadway conditions by choosing “Fill Roadway Details with Current Conditions,” or populate fields with current design standards by selecting “Fill Roadway Details with the Design Standards.”

Once “Add” is selected, a new tab will be added as a proposal in the top navigation bar titled.

(Add proposal pop-up)

Click the desired Proposal in the project navigation bar, and begin to enter the new proposed state for the project.

If your project involves removing an existing roadway, select “remove roadway” under the Roadway Type dropdown in your project proposal.

Each Proposal will display the Segment and Intersection characteristics for the project. Here, you can enter proposed changes to any existing roadway characteristics and determine their safety impact. As a change is made to the current conditions, the Adjustment Factor, and any changes to the Adjustment Factor are highlighted to the right of the proposed change.

(The Roadway Details section under “Current Condition tab” compared to the Roadway Details of Proposal 1, which was generated by selecting “Fill Roadway Details with Current Conditions.” Selecting this proposal option automatically populates these fields with the values input in the Current Conditions tab.)

(The Roadway Details tab of a proposal, when the “Fill Roadway Details with the Design Standards” option is selected; note how each field is auto-populated with the base condition.)

Changes can be made to the Roadway Details, Bike Details, and Pedestrian Details sections for each roadway in your project. By default, the current condition is populated in each field, so only the changed conditions need to be specified in a proposal.

Before completing a proposal, ensure the Cost section is complete. This indicates the cost associated with any proposed changes. You will need to enter the Construction Cost, Maintenance Cost, and Service Life of the proposed improvements. These values can be entered for each individual treatment for each Segment or Intersection or as a single total value.

(The Cost section for the Segment changes proposal)

The Summary section will illustrate any changes associated with the selected improvements.

(The summary page for the selected proposal)

The Comparison Summary tab summarizes the metrics and calculations for each proposed project and the no-build scenario.

From this screen, the various projects can be compared to each other, and the design with the greatest impact, and benefit-cost ratio can be easily identified.

(The Comparison Summary screen, comparing a proposed project, with the no-build scenario)

The Reference Table section displays the tables from the Highway Safety Manual that are used in the project. These tables are based on roadway type.

(The Reference Table)

An Alternative Design report can be downloaded for any saved Alternative Design. To download the report, click the Download icon located in the menu bar at the top of the screen (Note: if the Download icon is not displayed, it is likely because the project has not yet been saved).

A report preview will open, displaying the formatted report. To download the PDF of the report, click the Save & Download button located in the top right corner of the screen.

(The report preview screen of the selected project)

To save a project, select the “Save” button in the top right corner of your screen.

Name your project and indicate which category (or create a new one) to save it into. Saved projects without assigned categories are saved to the "Uncategorized" category by default. New categories can be added from within the Save Alternative Design pop-up menu.

Once a project has been saved, new menu options appear in the top-right corner of the screen.

The menu options from within a saved project are:

Delete: Delete the project.

To access your saved queries, select the home button in the top-left corner of the screen in the Alternative Design application.

This will take you to a page that displays the projects you’ve saved, as well as those that have been shared with you.

To share a project, select the three dots next to a project from within the library. Select “Share” and then “Add a user” and enter the emails of the users you’d like to share the project with in the pop-up box.

(Click the three dots next to a saved project to share the project, edit its name or category, or delete it)

Indicate the level of access you want shared users to have to the project: edit or view. Select "Done" when you’re finished.

(Use the drop-down menu next to shared user emails to choose if they have edit or view access)