Anyone who uses surface transportation has been affected by delays caused by various forms of weather. Whether it is rain or snow, ice or fog, the result is usually the same. Travel delay rises as traffic congestion increases.

The Federal Highway Administration’s (FHWA) Road Weather Management Program (RWMP) has been sponsoring research into the impacts of weather on surface transportation. One specific research task involved attempting to quantify the amount of travel delay imposed upon drivers due to the effects of inclement weather.

This paper will describe two different methods used to approximate travel delay impacts of weather along specific roadway segments around metropolitan Washington, D.C. Each method will use meteorological data sets of differing temporal and special resolutions in conjunction with travel time data.

The travel time data used in both models will first be described. Then, the two methods of analysis will be detailed along with their respective weather data. Results and conclusions from both analyses are then presented.