Thermal Mapping for MDSS Leon Shneider and Andy McDonald Vaisala Road Weather Systems

Thermal Mapping Across a highway network in winter some sections will be warmer or colder than others Thermal Mapping identifies where these warm and cold sections are going to occur Road pavement temperature data are collected automatically every 5 under a range of different weather types

Benefits of Thermal Mapping to MDSS MDSS provides point forecasts of expected road pavement temperature at a limited number of points Thermal Mapping provides a series of relative temperature maps to show how much warmer or colder the rest of the highway will be in relation to the forecast points Together - Thermal Mapping and point forecasts provide a complete highway network forecast of road pavement temperature Thermal Mapping is especially useful as a tool in the prediction of likely areas for ICE and FROST During February 2003 a series of Thermal Mapping surveys were undertaken on the MDSS trial area around Des Moines with the support of Iowa DoT……the results follow

Thermal Mapping – Des Moines NETWORK DETAILS Iowa DoT selected 15 winter maintenance routes to be used in the MDSS demonstration. Thermal Mapping was carried out along the entirety of the MDSS Winter Maintenance Routes. The MDSS Routes total approximately 192 miles. The Thermal Mapping surveys totalled c. 260 miles (inc. dead/free running etc). SURVEY DETAILS Feb 03Extreme Weather Conditions Feb 03Extreme Weather Conditions Feb 03Intermediate Weather Conditions Feb 03Damped Weather Conditions

ESS Location, I35: Variable pavement temperature profile

US Route 30 West onto I35 South Thermal Fingerprint Example Cold Bridge

Extreme Thermal Map

Intermediate Thermal Map

Damped Thermal Map

Des Moines Thermal Mapping Summary Winter road pavement temperatures varied by more than 14°F (including bridge decks) Large decreases in pavement temperature of 5°F or more can be seen when driving off the Interstate onto smaller, less trafficked State roads The positions of existing RWIS sites in the trial area are generally confined to warm sections of highway. There are much colder sections on the road network Combining point forecasts with Thermal Maps would provide a complete picture of road pavement temperature An example Thermal Mapping case study follows……..

Case Study

A82 Invergarry A82 Altnafeadh A85 Glen Ogle A9 Drumochter A889 Catlodge A86 Tullochroam A86 Roybridge A82 Spean Bridge A9 Calvine A9 Dunkeld A9 Inveralmond A82 Tyndrum

Analysis of Data (Forecast) – 21/22 March 2003 Note: Data from A85 Toft and A85 McAras Brae unavailable

Analysis of Data (Results) – 21/22 March 2003 Note: Data from A85 Toft and A85 McAras Brae unavailable

Thermal Maps How Accurate? Within 3°F provided the weather station forecast used is within 3°F of the actual How Do I Use the Information? Traditionally used to identify: Will any part of the network fall below zero? What will the minimum network temperature be? Used as a critical element in determining if treatment action required

TimeStep Maps

TimeStep Maps - Forecast 1.Are a new evolution of Thermal Mapping 2.Provide hourly time steps of forecast network surface temperature from 2200hrs to 0800hrs 3.Identify not only the minimum temperature BUT which roads will fall below freezing first and when 4.Facilitate fine tuning of treatment decisions – when should the treatment start to ensure roads are treated BEFORE the freezing point is reached

Questions?