 |
Significant queues occurring on a two-lane highway
(violates assumption that the flow is uninterrupted). |
|
Backup from one intersection affecting the movement of
traffic from another intersection. |
|
Overflow of a storage bay that inhibits the movement of
through traffic. |
|
Short sections of a longer facility that have a
different cross section than the main facility. |
|
Control features that are not covered by the HCM
procedures (e.g., three-way stop at a four–legged intersection. |
| Conditions that would suggest the use of traffic models
that are more complex than the HCM to accommodate phenomena that
are not envisioned by the HCM (e.g., signal preemption,
platoon
propagation and dispersion, advanced traffic control strategies, etc.). |
It is important therefore to examine all points in a
facility to identify any abnormal conditions that could affect the
procedures or the results.
A specific condition could require a modification in the
way a procedure is implemented to achieve more valid results. Another approach is to make a simplifying assumption
in order to proceed with the analysis, followed by some post processing of
the results for reasonableness. In some cases,
especially those in which the demand volumes exceed the capacity, it could
be preferable to eliminate the condition by, for example, assuming an improvement that increases
the
capacity. The objective of this sub-problem is simply to identify such
conditions and not to prescribe the measures by which they should be
accommodated. The accommodation of abnormal conditions will be dealt with
under the site-specific sub-problems to be presented later.
[
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] with Sub-Problem 1c
