Download presentation
Presentation is loading. Please wait.
1
3/3/06Michael Dixon1 CE 578 Highway Traffic Operations Freeways Merge Influence Areas
2
3/3/06Michael Dixon2 Objectives Estimate flow entering influence area Estimate capacity and determining LOS Special cases (next class)
3
3/3/06Michael Dixon3 Flow Entering Influence Area (V 12 ) V 12 = P FM * V F 4-lane freeways (P FM = 1.0) 6-lane freeways more complex 8-lane and 10-lane freeways
4
3/3/06Michael Dixon4 Flow Entering Influence Area (V 12 ): Choosing the P FM Equation four-lane: P FM = 1.0 eight-lane: only one choice ten-lane: only one choice six-lane: See Exhibit 25-6
5
Flow Entering Influence Area (V 12 ): Choosing the P FM Equation 3/3/06Michael Dixon5
6
3/3/06Michael Dixon6 Flow Entering Influence Area (V 12 ): Choosing the P FM Equation (cont.) Only an issue for six-lane freeway sections On-ramps do not affect V 12 If only on-ramps are involved Eq. 1 If an off-ramp is involved calculate L EQ if L EQ < L up and/or L down then use Eq. 1
7
3/3/06Michael Dixon7 Steps for Evaluating a Merge Area Calculate the adjusted volumes (V R, V F, V D ) Step 1: Evaluate the equilibrium distance Step 2: Calculate P FM Step 3: Calculate V 12 Step 4: Calculate total flow entering merge area (V R12 )
8
3/3/06Michael Dixon8 Steps for Evaluating a Merge Area (cont.) Step 5: Capacity for downstream freeway segment (c 1 ) Step 6: Capacity for merge influence area (only if v/c for step 5 is less than 1)(Exhibit 25-7) Step 7: Determine the LOS of the influence area (only if v/c for step 5 is less than 1)
9
3/3/06Michael Dixon9
10
3/3/06Michael Dixon10 Six-Lane Example: Conditions
11
3/3/06Michael Dixon11 Six-Lane Example: Step 1
12
3/3/06Michael Dixon12 Six-Lane Example: Step 2 and 3
13
3/3/06Michael Dixon13 Six-Lane Example: Step 4 and 5
14
3/3/06Michael Dixon14 Six-Lane Example: Step 6 and 7
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.