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How should I model TNM roadways when considering grade adjustments?

April 26, 2017adjustments considering grade model roadways TNM

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How should I model TNM roadways when considering grade adjustments?

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Each mainline should be modeled as a continuous TNM Roadway (not several, strung together end to end) especially when dealing with grade adjustments. When importing STAMINA files that have several roadways and grades in each segment, be sure to combine these roadways into one long TNM roadway, since TNM does not link speeds between roadways. You should not start a mainline roadway in the middle of a road with an upgrade. If you have to start a new TNM roadway some distance on an existing roadway with an upward grade, you may want to manually input a lower speed for heavy trucks. You may calculate this speed using Figure 46 on Page 57 of the TNM Technical Manual. Heavy trucks will already be slowed down from the point where the grade meets the new roadway. Be sure to model a separate truck lane, if one exists.