1. 3/6/06Michael Dixon1 CE 578 Highway Traffic Operations Freeways Ramps and Ramp Junctions Examples and Special Applications for Merge Areas

2. 3/6/06Michael Dixon2 Objectives Analysis for six-lane freeways Analysis for eight-lane freeways Analysis of special cases

3. 3/6/06Michael Dixon3 Special Cases Ten-lane freeways Two-lane on-ramp Major merge areas Lane additions Left-hand on-ramp

4. 3/6/06Michael Dixon4 Special Cases: Ten-Lane Freeways Same as eight lane analysis Use Exhibit 25-11 Use Equation 25-7 Use v F4eff in Eight-lane equation for P FM

5. 3/6/06Michael Dixon5 Special Cases: Two-Lane On- Ramp

6. 3/6/06Michael Dixon6 Special Cases: Two-Lane On- Ramp Densities Relative operations Two changes to basic methodology –Calculation of P FM –Length of acceleration lane for calculation of density  Capacity values are unaffected for v FO and v R12.

7. 3/6/06Michael Dixon7 Special Cases: Major Merge Areas

8. 3/6/06Michael Dixon8 Special Cases: Major Merge Areas Each entering roadways is at or near freeway design standards No acceleration lanes involved Analyze as if the two entering and the one exiting legs are basic freeway sections, using Exhibit 25-7

9. 3/6/06Michael Dixon9 Special Cases: Lane Additions One lane addition –ramp roadway capacity governs –analyze downstream leg as basic freeway section Two lane addition: analyze as major merge area Lane dropped within 2500 ft: analyze as weaving area

10. 3/6/06Michael Dixon10 Special Cases: Left-Hand On- Ramp Influence area same length  left two lanes Calculate P FM for left two lanes Capacity Density Speed