Sub-problem 1b - Page 6 of 9

ID# C201B06

Sub-problem 1b: Maxwell Drive PM Peak Hour - With Conditions

Critical Movement Technique
A sequence of specific movements (in specific lanes), one for each phase, determines the minimum cycle length. In a dual ring controller, configured as shown in Exhibit 2-11, some sequence of the four movements - either 1,2,3,4; 1,2,7,8; 5,6,3,4; or 5,6,7,8 - will define the minimum cycle length.

Exhibit 2-16 shows the results that were obtained using the critical lane analysis for eight different scenarios. We have assumed that the saturation flow rates for the various lane groups are as indicated by the note below the table and that the lost time per phase is as shown in the second column.

Exhibit 2-16. Maxwell Drive Critical Movement Analysis Results

Scenario

Lost Time (sec)

Number of Lanes

Cycle Length

Notes

Eastbound

Westbound

Northbound

Southbound

LT

TH

RT

LT

TH

RT

LT

TH

RT

LT

TH

RT

C-1

3

1

2

1

2

1

1

1

1

1

1

139.4

N & S RT lanes dominate N & S TH and RT timings

C-2

4

1

2

1

2

1

1

1

1

1

1

175.5

Scenario 1 except 4 sec lost time per movement

C-3

3

1

2

1

2

1

2

1

2

93.5

N & S TH & RT incorrectly grouped together

C-4

3

1

2

1

2

1

1

1

1

1

1

114.9

N & S Right turns allowed concurrent with E & W LT's

C-5

3

1

2

1

2
1
1

1

1

1

1

1

87.2

Scenario 2 with new WB RT lane

C-6

3

1

2

1

2

1

1

1

1

204.9

N & S TH/RT in single lanes

C-7

3

1

2

1

2

2

1

2

1

106.7

Scenario 6, except simultaneous double LT's N& S

C-8

3

1

2

1

2

3

3

84.4

Separate N & S Phases

Note: Saturation flow rates: 1,800 for throughs, 1,700 for rights, 1,500 for lefts, 1,700 for double lefts, 1,800 for 3-lane group

From the table, we see the following: in Scenario C-1, the cycle length we obtain is shorter than that in the planning analysis. (This scenario is the same as the first scenario we studied in the planning model analysis.) This is because we used 3 seconds of lost time per phase instead of 4. If we use 4 seconds, as is the case with Scenario C-2, we get a cycle length very similar to the one we obtained in the planning analysis (175.5 seconds versus 171.4). This means the two methods are very similar for that condition.

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