Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Appendices
Transponder systems are equipped with identification tags on the vehicle and a roadside reader.
When a vehicle is within the detection range of the reader, the tag communicates information
about the vehicle’s speed, position, and direction to the roadway central office through a dedicated
data link such as a wireless network. A radio frequency identification (RFID) system is an example
of a transponder system. Bluetooth Mobile Access Code (MAC) readers have similar
architecture—detecting and logging a Bluetooth wireless device’s addresses, and matching the
presence and times of detection of these addresses at successive receivers allow for the calculation
of travel time and assessment of travel routes (origins and destinations). Unlike speed detectors
that record speed at a single location, Bluetooth technology directly samples travel time through a
corridor. Transponder systems (antennas, readers and checkpoint stations) tend to have a higher
cost than video detection and radars (point detection)—one disadvantage of this system.
2.3. Pre-trip Information
Providing information on planned disruptions in advance, whether it is for construction zones or
special events can greatly increase reliable travel since travelers can better plan for their trip and
adapt in terms of route and timing. Event transportation management systems can help control the
impact of congestion at stadiums or convention centers. In areas with frequent events, large
changeable destination signs or other lane control equipment can be installed. In areas with
occasional or one-time events, portable equipment can help smooth traffic flow. The key strategies
for this subcategory relate to the preparation and dissemination of pre-trip information.
National Traffic and Road Closure Information. The FHWA National Traffic and Road
Closure information website (12) provides real-time information regarding weather, road, and
traffic conditions for travelers and freight shippers nationwide. Pre-trip information is available for
all 50 states and a collection of local websites is also provided by state as well.
Planned Special Events Management. Special events cause congestion and unexpected delays to
travelers by increasing traffic demand or reducing roadway capacity (e.g., street closures for
parades). Advanced planning and coordination of events allow agencies to develop and deploy the
operational strategies, traffic control plans, protocols, procedures, and technologies needed to
control traffic and share real-time information with other stakeholders on the day of the event.
These capabilities allow agencies to proactively manage and control traffic to accommodate the
increased travel demand generated by the event and use the available roadway capacity in the most
efficient and effective manner (6).
2.4. Real-time Information
Advanced communications have improved the dissemination of information to the traveling
public. Motorists are now able to receive relevant information on location-specific traffic
conditions in a number of ways, including mobile and web services, highway advisory radio
(HAR), and 511 systems. In the future, “in-vehicle signing” would include static sign information
(e.g., stop, curve warning, guide signs, service signs, and directional signs) and dynamic
information (e.g., current signal status including highway intersection and highway-rail
intersection status and local conditions warnings identified by local environmental sensors). It
would include short-range communications between field equipment and the vehicle and
connections to the Traffic Management Subsystem for monitoring and control. This would also
include the capability for maintenance and construction, transit, and emergency vehicles to
transmit sign information to vehicles in the vicinity so that in-vehicle signing can be used without
fixed infrastructure in work zones, around incidents, and in areas where transit operations impacts
traffic. The information that drivers obtain in “real-time” as they travel is highly valued by drivers
ADDITIONAL DESCRIPTION AND QUANTITATIVE BENEFITS OF TRAVEL-TIME RELIABILITY STRATEGIES Page F-3