SpeedImpact — one study

Roads with data · current limit
≤50 60–70 80–90 100+ km/h unknown
treatment comparison

Search a place or pan the map, then Load roads here. Click roads to add them to the treatment corridor; switch to comparison to pick control roads.

1 · Place

2 · Roads

Treatment: the roads where the intervention applied. Comparison: similar nearby roads it did not affect.

Treatment

none yet

Comparison

none yet

3 · Intervention

Type

Date it took effect

Date certainty

Limit before

Limit after

Washout after (days)

Limits are as you declare them: the data only knows today's limit.

Months before

Months after

Evidence for the date (gazette, media release, works record) Study title

4 · Comparison roads

I confirm the comparison roads were not affected by the intervention, diverted traffic or concurrent works.

5 · Method

Descriptive before/after Comparison-adjusted (DiD) Gated comparison

All three rows are computed and reported; this choice sets the headline. None of them is a measured effect of the intervention on journeys: the gated row adds pre-registered diagnostic gates and returns no number unless every gate passes. Interrupted time series is not offered until it has been validated.

Sealing fixes the question (roads, dates, windows, method) with a SHA-256 hash before any after-period number exists.