Capacity Analysis of Interchange Ramp Terminals Final Report (1997) / Chapter Skim
Currently Skimming:
APPENDIX E Arterial Weaving Speed Models
APPENDIX E Arterial Weaving Speed Models
Pages 315-332
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 315... ...
Freeway weaving sections operate under uninterrupted flow conditions while arterial weaving sections operate under interrupted flow due to upstream and downstream traffic signals. Another difference is that a freeway weaving section has a fixed length that is based on the distance between its entry and exit points while an arterial weaving section has a varying length as a result of downstream queues.
|
From page 316... ...
. 4 - "Yes" indicates we paw is present in arterial weaving sections in interchange areas.
|
From page 317... ...
. Movement type describes how a vehicle enters or exits the weaving section (e.g., left, through, right)
|
From page 318... ...
He collected width, length, angle of approach, alignment deflection angle, speed, and volume data at twenty arsenal weaving sections and used this data to calibrate weave and non-weave speed models similar to those in HCM. He demonstrated how his models yielded better estimates ofthe weave and non-weave speeds than did He Leeway models provided In the HCM, even after he calibrated the HCM models wad his data.
|
From page 319... ...
In theory, He weaving maneuver arid arterial entry speeds would be similar when the weaving flow rate is negligible. However, the weaving speed would decrease as the weaving flow rate increases or when the arterial flow rate increases such Hat crossing opportunities decrease.
|
From page 320... ...
(E-2) Like the rationale for the weaving maneuver speed model, the arterial maneuver speed mode} is based on the assumption Mat weaving speed should equal the arterial entry speed when the weaving flow rate is negligible.
|
From page 321... ...
A distinction is made in the computation of Pu based on the length of the weaving section. Specifically, weaving sections are referred to as "short" or "Ion"" depending on the nature of the weaving maneuver.
|
From page 322... ...
ot course, me queue would continue to grow as other weaving vehicles joined it. For practical applications of Equation Em, [q w cart be conservatively estimated as Me average maximum queue length per cycle at the downstream intersection based on the arsenal flow rate entenug the weaving section Va.
|
From page 323... ...
| Lw Length of the weaving _ | U., Average arterial entry ~ reed | rn/s | 8.9 | 21.8 | | Va Avg. arterialflow rate Itering the weaving section | vph | 640 | 1,924 | V`,/N, Average arterial flow rate per lane vphpl 320 676 Weaving | Iq,, w Queue length joined b' _ 60.0 ~ | Pu Probability of a weaving ~[ | Vw Average weaving flow ate | vph | 88 | 270 |[ | dm w Maneuver distance for .
|
From page 324... ...
As these statistics suggest, Me weaving maneuver speed model (i.e., Equation E-6) accounts for 16 percent of Me variability in Me maneuver speed data Likewise, Me arterial maneuver speed mode!
|
From page 325... ...
This omission has a larger impact on the weaving maneuver speed model because many weaving vehicles accelerate from the off-ramp (i.e., they arrive on the red indication or have to yield) while others enter at speed.
|
From page 326... ...
Predicted versus measured arterial maneuver speed. E.~.6 Sensitivity Analysis The effects of arterial flow rate, weaving flow rate, arterial traffic lanes, and weaving section length on maneuver speed are examined In this section.
|
From page 327... ...
This trend is reasonable and suggests that the capacity of the weaving section is dependent on the combined arsenal and weaving flow rates.
|
From page 328... ...
Weaving Maneuver Speed, m/s 8 7 6 1600 1800 Ua= 13.4m/s Nt = 2 lL=o 600 800 1000 1200 1400 1600 1800 Average Arterial Flow Rate, vph Figure E-S. Effect of weaving flow rate on weaving maneuver speed.
|
From page 329... ...
This trend is reasonable since a vehicle can attain a higher speed when it has a longer distance In which to maneuver. Weaving Maneuver Speed, m/s ~ t~n9~, an 9 8 6 Ua = 13.4 m/s No = 2 Vw= 170vph 1 - 90~_ 600 800 1000 1200 1400 1600 1800 Average Arterial Flow Rate, vph Figure E-6.
|
From page 330... ...
The mode} calibration also indicated that weaving maneuver speed is dependent on the weaving flow rate, weaving section length, and the probability of Me weaving vehicles being blocked. Separately, both models show strong correlations with the measured maneuver speeds and can be used to estimate the mean maneuver speed with a precision of less than +0.2 m/s.
|
From page 331... ...
42-48. Vermijs, R., and Schuu~man, H., "Evaluating Capacity of Freeway Weaving Sections and OnRamps using the Microscopic Simulation Mode} FOSIM." In Proceedings of the Second International Symposium on Highway Capacity, Volume 2, (Ed: Akcelik, R.)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.