A plain-English guide for traffic engineers, planners, and grant writers. No code, no database talk — just how to use the tool to build a defensible case for a safety project. Fact-checked against the live app 2026-08-28.
You can always get back to this guide from inside the app — click the Help link at the top right of any screen.
You have a project you think will save lives — a roundabout, a signal, a rumble strip, a road diet. Someone (a council, a state DOT, a federal grant reviewer) is going to ask: is it worth the money?
BC Cost Calculator answers that question using your agency's own real historical crash data, real federal safety-performance research, and a real statistical simulation — not a guess. It produces a Benefit-Cost Ratio (BCR), a formal report you can hand to a reviewer, and the underlying math to back it up if anyone asks to see it.
Every formula behind these results — crash costs, safety performance functions, the Empirical Bayes adjustment, the Monte Carlo simulation — has been independently checked against real federal and academic sources (FHWA, the Highway Safety Manual, NCHRP), not assumed correct. Where a number is a judgment call rather than a fixed federal standard (like a discount rate), the app tells you so and cites the source instead of quietly picking one for you.
The app opens directly into Guided Setup, a four-step wizard. There's no separate home screen to find — you're always one click from step 1.
At the top of this screen is a quick status strip showing when your agency's Weather, MIRE Roadway, and Crash data were each last refreshed — with a one-click Update link that jumps straight to where you'd refresh any of them (hover the crash-count icon for a year-by-year crash count). Worth a glance before starting a new study, so you're not building on stale data without realizing it.
Tell the app where you're evaluating and how far back to look:
Set a start and end date, then click Run Crash Query. The app pulls every matching crash from your agency's real crash records and lists them — key, date, distance, severity, and the first harmful event. You can:
Crash Density Heatmap — the checkbox above the map turns on a color-graded heatmap of real crash locations, so you can see where activity clusters before you even narrow in on a site. Choose Statewide (every crash in your agency's data, for a date range you set) or Study Area (just the crashes within your current search). Filter by severity with the K/A/B/C/O checkboxes, or use the one-click K+A Only preset to see just the fatal/serious-injury crashes. Statewide loads require a date range first — this keeps the query from trying to pull years of crashes across an entire state at once.
This is where you pick what you're actually proposing to build. The app gives you a searchable library of real countermeasures pulled straight from the FHWA/CMF Clearinghouse's own database — thousands of entries across roughly 19 categories (intersection traffic control, roadway, shoulder treatments, signing, lighting, and so on).
Filter by category, keyword, road type, or intersection type. Two checkboxes narrow things fast:
Each entry shows its Crash Modification Factor (CMF), a star rating for study quality, and a direct citation link back to the original study — so if a reviewer asks "where did that number come from," you can show them. Click + Add to select one or more; you'll see them collected in a "Selected" panel at the bottom.
Enter the economics of the project:
A live preview panel shows your Total Present Value of Costs, Equivalent Uniform Annual Cost, and Capital Recovery Factor as you type — no need to click anything to see the effect of a change.
This is where the crash-reduction math happens, and where you actually run the analysis.
First, you set the baseline — how many crashes would this location be expected to have without your project. Three ways to do that:
Once the baseline is set, review the Observed vs. SPF-Predicted Crashes table (auto-filled from your Step 1 search), optionally adjust the Overdispersion Parameter, and leave Monte Carlo Iterations at its default of 2,000 unless you have a reason to change it. Then click Run Analysis.
After you run the analysis, the app switches to an Executive Dashboard view with the numbers a reviewer actually cares about:
| What you'll see | What it means |
|---|---|
| Mean BCR | The average Benefit-Cost Ratio across 2,000 simulated scenarios — your headline number. A BCR above 1.0 means the crash-cost savings outweigh what the project costs to build; the higher above 1.0, the stronger the case. |
| Median / 5th–95th range | Shown right under the Mean BCR — this is your honest range of outcomes, not a single guess. A tight range means high confidence; a wide range means real uncertainty in the inputs. |
| Expected NPV | The dollar value of net benefit over the project's service life, with its own range. |
| Threshold Status (Pass/Fail) | The app compares your Mean BCR against your own agency's configured BCR threshold (set on the Configuration page — this is not a fixed number baked into the software, so check what your agency has it set to). You'll see a plain ✓ Pass or a Fail, plus how many of the 2,000 simulated trials cleared the bar. |
| Monte Carlo BCR Distribution (histogram) | A visual of where all 2,000 simulated outcomes landed. Bars at or above your threshold are highlighted — a good gut-check for how comfortably a project clears the bar versus scraping by. |
One thing to know: the Mean BCR for a saved study is stable — reopening it later, or viewing it from the LRSP report, Compare Studies, or What-If Analysis, always shows the same number. The app caches the simulation result per study rather than re-sampling fresh every time you look at it, so it only changes if something about the study's real inputs actually changes (a corrected crash, a recalibrated CMF, an updated cost) — never just from revisiting it.
Want to show your work? Click View Detailed Calculation Proof on the results screen. It opens the full crash-type-by-crash-type Empirical Bayes table — observed crashes, SPF-predicted crashes, EB weight, and the final adjusted estimate for every severity and crash type — so a technical reviewer can redo the math by hand if they want to. Nothing about the result is a black box.
Already built a study and want to see how a different price tag or a shorter service life would change the outcome — without touching the original saved study? Go to Analysis → What-If Analysis.
Pick any completed study from the list and click Open Sandbox. Three sliders appear — Project Cost, Discount Rate, Service Life — and the BCR and NPV update live as you drag them, with no page reload and no risk of overwriting your saved numbers. It's a genuine "what if we spent $200K less" sandbox.
Need to change something beyond those three (a different countermeasure, a wider search radius, a new date range)? Click Edit full study in Guided Setup to jump back into the real wizard.
Once you've got one or more completed studies, the app can assemble them into two federally-recognized document formats.
An LRSP is itself an FHWA-recognized Proven Safety Countermeasure — a structured framework agencies use to document how they identify and prioritize safety projects. This page automatically pulls together every saved study into one report: an executive scorecard (sites analyzed, crashes reviewed, how many studies pass your BCR threshold, total project cost), an auto-generated narrative summary, a Passed/Failed line for every site, and an appendix of real crash-trend charts (day-of-week and weather conditions, pulled from NOAA's actual historical weather data for each crash's date and location — not just an officer's field notes).
Click Print LRSP Report, then use your browser's print dialog and choose Save as PDF. Tip: if your browser adds its own header/footer (a URL and date stamped on every page), open "More settings" in the print dialog and turn off "Headers and footers" first — that produces the cleanest document.
This assembles the full 8-component structure USDOT's Safe Streets and Roads for All (SS4A) program requires of a Comprehensive Safety Action Plan:
Components 3 (Safety Analysis) and 7 (Strategy Selections) are generated automatically from your real saved studies — the same underlying data as the LRSP report. The other six are narrative sections only your agency can supply; fill in the fields provided (leadership commitment language, target dates, equity considerations, etc.), click Save Progress as you go, and click Export SS4A PDF when it's ready to submit.
The remaining menu group, Data & Config, is initial setup and administration (importing crash data, mapping data fields, configuring your agency's CEAs and BCR threshold) — worth knowing it exists, but not something you'll touch on a day-to-day project evaluation. One part of it deserves its own explanation, because it's easy to get the order wrong with no error message telling you so:
This trips people up, so here it is plainly: there are two different screens, and the second one does nothing useful until the first one is done.
If you do Step 2 before Step 1, you'll see something like "Enriched 0 segment(s); 0 skipped" and nothing will happen — no error, just nothing. That's not broken. It means Step 1 hasn't been done yet, so there's nothing for Step 2 to attach data to. Go back and do Step 1 first.
Systemic Screening (above) only strictly needs Step 1 — your roads have to exist for it to find anything at all. Step 2 isn't required, but the more detail your roads carry, the more risk factors screening actually has to work with, so it's worth doing if your state publishes that data.