The large volume of private vehicles on the road today.
The age and capacity of the roads and highways.
Accidents and road construction.
The management, integration and presentation of real-time traffic information.
The costs of constructing new roads.
Reliable construction updates.
Real-time transportation system information.
Sufficient Federal funding.
Mature cellular networks.
Inductive loop detection devices
They could not accurately measure a driver's speed.
They could not distinguish between traffic slowdowns and deliberate stops on the part of the driver.
People would not consent to participate in the test.
Most people turn their cell phones off in the car.
Reflections and obstructions prevented a good measurement of drivers' locations.
Not every driver carries a cell phone.
Cell phones cannot provide precise location information.
Cell coverage is not uniform in a metropolitan area.
Cell phone companies may not be willing to cooperate with the study.
From driver registration data.
Toll tag readers measure the travel time of tag holders between readers.
Driver data is entered into the system when drivers pass a toll booth.
Driver data is logged when drivers enter and exit the system.
Drivers are located using RFID tags.
The TRANSMIT system can measure travel time of particular drivers.
A large number of drivers can be tracked.
The TRANSMIT system comes with a "ready-made" set of participants.
Drivers can report real-time traffic conditions.
TRANSMIT tags can be tracked from aerial surveillance patrols.
The probes can be placed in areas where other data collection methods fail.
Probes can be moved from place to place.
Probes are less expensive than other types of traffic counting devices.
Probes provide a wider range of information than other traffic counting devices.
Information can be captured over multiple links or over various time periods.