Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
amount of precipitation that falls. Therefore, the more geographically precise the collected
weather data can be, the better it is.
Work Zones/Construction
The key construction variables that affect reliability are as follows:
• Location of the construction event
• Time and duration of lane/shoulder closures by extent of closure
• Time, duration, and nature of lane modifications/shifts made during construction activity
These variables would ideally be reported in real time by staff working at the construction site.
The data would then be posted to traveler information sites and broadcast to the traveling public.
This rarely occurs, but construction traffic mitigation plans and construction schedules are
usually available. These documents outline the planned modifications to the subject travel lanes
during the scheduled construction activity. There will be a clear picture if they describe both the
times of day and the calendar days during which the lane closures will be put in place. Because
actual construction activities will differ from these plans as a result of a variety of factors
(weather, changes in construction plans, etc.), these data have limitations but are useful when the
relative effectiveness of traffic management plans is assessed.
Special Events
The key special event variables are the following:
• Location of the event
• Attendance at the event (vehicle demand)
• Duration of the event.
Special events impact the performance of roadways in two ways: 1) they significantly increase
traffic volumes prior to and after the event and 2) they change the origin/destination travel
pattern of trips using roadways associated with those events. As a result, they change the vehicle
volume on roadways in the vicinity of the event venue and the parking lots that serve that venue.
The above variables allow estimation of those traffic volume changes. The difficulty is in
identifying special events. Some events are easy to identify (e.g., large college football games or
traditional Fourth of July fireworks displays); but other events (e.g., large company gatherings
occurring on weekdays at urban conference centers or stadia) can be difficult to identify and
collect data on. Similarly, attendance at smaller venues may have significant impacts near the
venue itself, but go unnoticed on the freeways that serve the larger geographic area surrounding
that venue. This makes it somewhat challenging to determine which event data to collect.
Traffic Control/Signal Timing
Data on traffic-control plans are needed to understand the level of roadway capacity that
roadway agencies are providing. At a minimum, data desirable to maintain includes the
following:
• The location of all traffic-control mechanisms
• The time that specific control plans or actions take effect
• Descriptions of all signal-timing phases (as planned, and if possible, where executed)
• Location, description, and timing of all non-signal control actions taken (e.g., what
messages are placed on which dynamic message signs during which time periods, or what
rates are charged on HOT or managed roadway lanes at specific times of the day).
GOALS AND PERFORMANCE TARGETS Page 30