1. 9/23/2009Michael Dixon1 CE 578 Highway Traffic Operations Crawl Regions and Specific Grades HCM 2000

2. 2/11/2006Michael Dixon2 Objectives Model vehicle operations on grades using the HCM 2000 two-lane highway directional analysis procedure Evaluate need for climbing lanes

3. 2/11/2006Michael Dixon3 When to Use HCM 2000 Specific Grades Procedure: Upgrades NO –Level Terrain: –Rolling Terrain: MAYBE – MUST –

4. 2/11/2006Michael Dixon4 % Grade –Upgrade same as downgrade –Composite grade  Total elevation change / length

5. Length 2/11/2006Michael Dixon5

6. Length (composite grade) 2/11/2006Michael Dixon6

7. 2/11/2006Michael Dixon7 How to Use the HCM 2000 Specific Grades Procedure: Upgrades Use the modified directional analysis procedure making the following replacements Average Travel Speeds –fG: –ET and ER: PTSF –fG: –ET and ER: Everything else is the same

8. 2/11/2006Michael Dixon8 Criteria for Evaluating the Need for Climbing Lanes (AASHTO) 1.Upgrade traffic flow rate in excess of 200 vehicles per hour 2.Upgrade truck flow rate in excess of 20 vehicles per hour 3.One of the following conditions exists: a)A 10 mph or greater reduction is expected for typical heavy truck b)Level of service E or F exists on the grade c)A reduction of two or more levels of service is experienced when moving from the approach segment to the grade

9. 2/11/2006Michael Dixon9 When to Use HCM 2000 Specific Grades Procedure: Downgrades Opposing direction of any upgrade

10. 2/11/2006Michael Dixon10 How to Use the HCM 2000 Specific Grades Procedure: Downgrades Use the modified directional analysis procedure making the following replacements Average Travel Speeds (no trucks at crawl speeds) –f G : –E T and E R :

11. 2/11/2006Michael Dixon11 How to Use the HCM 2000 Specific Grades Procedure: Downgrades (cont.) Average Travel Speeds (trucks at crawl speeds) –f HV : –f G : –E T and E R : –E TC : Extra data: percentage of trucks operating at crawl speeds

12. How to Use the HCM 2000 Specific Grades Procedure: Downgrades (cont.) 2/11/2006Michael Dixon12

13. 2/11/2006Michael Dixon13 How to Use the HCM 2000 Specific Grades Procedure: Downgrades (cont.) PTSF –fG: –ET and ER: Everything else is the same