New to Alternative Design? This quick start covers the essentials: how the screen is laid out, how a project moves from step to step, what to have ready, and the few rules that keep a project on track. Each section links to the full article when you're ready for more detail.
ℹ️ Note: Numetric and AASHTOWare Safety are the same software. Agencies that license it through AASHTO know it as AASHTOWare Safety.
What Alternative Design Does
Alternative Design predicts crashes on the segments and intersections you choose, using the Highway Safety Manual (HSM) predictive method. You describe the road as it is today, set a No-Build baseline, and add proposals, such as new lighting or a road diet. Then you compare the proposals on expected crashes, safety benefit, and benefit-cost ratio.
Getting Around
Every tab after Project Selection has the same layout.
(The five areas of the Alternative Design screen)
Header: The project name, the crash date range, and the project buttons.
Tabs: One tab for each step, plus a tab for each proposal.
Sidebar: The pages for the current tab.
Work area: The fields and results for the selected page.
Map: Click View Map to show it beside your work.
How a Project Moves
A project moves left to right through the tabs. On Current Condition, No-Build, and each proposal, the sidebar also lists pages. Work down the pages, clicking Continue on each one. Continue on the last page takes you to the next tab.
(The six tabs of a project)
Project Selection: Add the segments and intersections to study.
Current Condition: Describe each location as it is today.
No-Build: Set the analysis period, AADT growth, and analysis method.
Proposals: Model a design and enter its cost.
Comparison Summary: Compare the No-Build and every proposal side by side.
Reference Table: See the HSM tables behind the calculations.
⚠️ Warning: Move through a project with the Continue button at the bottom of each page, not by clicking the tabs. Continue is what saves your entries and carries them forward.
(The Continue button at the bottom of each page)
Before You Start
Have these ready to make the first project go quickly:
Your locations: The segments and intersections you want to study, and where each one starts and ends.
Roadway characteristics: Details such as lane configuration, lighting, parking, and turn lanes. Some fill in automatically if your organization has set up asset data.
Traffic volumes: AADT fills in automatically when data is available. Otherwise, have your counts on hand.
Analysis period: How many years to analyze and the expected annual AADT growth.
Costs: Construction cost, maintenance cost, and service life for each proposal.
Describe the Current Condition
For each location, fill out the Information, Roadway Details, Bike Details, Pedestrian Details, and Crashes pages. Required fields display a warning until you fill them in.
(Each value you enter updates the location's adjustment factor)
Roadway Type: Choose it first. It decides which fields you fill in, which HSM calculations are used, and which adjustment factors apply.
Current AF: Shows how each characteristic affects the prediction. A value of 1.00 matches the HSM base condition.
Observed crashes: The Crashes page pulls them in for the project's date range.
ℹ️ Note: Proposals stay locked until every Current Condition page is filled out.
Set the No-Build
The No-Build is the baseline: what happens if nothing changes. Every proposal is compared with it.
(No-Build Options set to 20 years with 1.5% annual AADT growth)
Years: The years you enter on the Options page set the analysis period for the whole project. Proposals use them too.
Analysis Method: Alternative Design recommends a method. Expected (Empirical Bayes) combines the prediction with the observed crashes.
Add Proposals
A proposal is one design you want to test. You can add up to 10, and each one gets its own tab.
Click + Add Proposal in the top-right corner, choose a starting point, and click Add.
Change only what the design changes. Changed values turn blue.
On the Cost page, enter the construction cost, maintenance cost, and service life.
(A green down arrow means the change lowers predicted crashes)
Compare and Share Results
The Comparison Summary tab puts the No-Build and every proposal side by side.
(The Comparison Summary for two proposals)
Benefit Cost Ratio: The safety benefit for each dollar spent. A ratio above 1 means the benefit is greater than the cost.
Expected Crashes: Predicted crashes over the analysis period, by severity.
Summary Settings: Choose which locations and proposals to show. The report uses the same choices.
Save and Download
Click Save in the top-right corner to save the project. After the first save, the header adds buttons to favorite, copy, share, download, and delete it. Click the Download icon to create a PDF report of the Comparison Summary.
(The Download icon in the header of a saved project)