Published 14 October 2026 · Source-linked research prepared with AI assistance. Proposed services require an agreed scope and qualified delivery team.
Define the visibility question
An operator may need to understand recurrent fog at a valley entrance, smoke affecting an evacuation route or reduced visibility near a bridge. Define the location, direction, season, operating period and physical threshold. Fog and smoke can both reduce optical visibility, but they may require different observations, response procedures and specialist interpretation.
Check representativeness
Review terrain, elevation, sight lines, road geometry, nearby water and possible local sources. A sensor near an interchange can miss a fog bank several miles away. Use field observations and the authority’s records to choose comparison locations. Document the area each measurement can reasonably describe rather than drawing an unjustified corridor-wide safe zone.
Align observations with the operating record
Normalize timestamps and units, preserve missing intervals and identify changes in instruments or reporting frequency. Separate a restriction, a warning, a traffic queue and a crash. Extra reports during bad conditions can bias simple counts. Historical associations can identify questions for investigation without proving that weather caused a particular incident.
Use the first study to specify the pilot
The output should identify observation locations, reference measurements, sampling interval, quality flags, maintenance access and data acceptance criteria. The road authority defines operational thresholds and response. A Weatherhill study does not remove fog, certify a route as safe or authorize a warning system to control traffic.
Sources & further reading
- FHWA EDC News: Weather-Responsive Management Strategies ↗I-77 roughly $7.5M, 12 miles, nearly 75% fewer low-visibility crashes; 2013–2022 fatal-crash weather context.
- USDOT FHWA Weather Data Environment catalog ↗Existing road-weather data collection, quality checks and archive.