GNSS Markets and Applications - Understanding GPS: Principles and Applications - page 647

systems (ITS). These systems are meant to modify traffic flow according to demand
and other factors. One way to do this involves the monitoring of the progress of
vehicles that are transmitting their position to a central location. Traffic signals or
rerouting signs can then be used to respond to situations where a particular probe
vehicle is not progressing as it should under optimum conditions. Another aspect of
ITS involves the automatic collection of highway and other tolls and tariffs. This
eliminates the need for vehicles to stop at state lines or at toll booths on toll roads
and bridges if their position is being reported and appropriate accounting arrange-
ments are made between the tariff-collecting authority and the vehicle's operator.
This is most appropriate for commercial operations, but it is not inconceivable that
private automobiles could be subject to the same kind of system. It would be possi-
ble in early implementation to provide a through lane at toll booths for appropri-
ately equipped vehicles. GPS is not central to this kind of technology. Since the
location of the required toll payment is always known, the vehicle's passing of a
local code reader would initiate toll billing. Yet there are other potential tariff sys-
tems where total road usage could be tracked and taxed rather than just on given
roadways, as is done now. While the United States is unlikely to adopt such a reve-
nue collection system, the EU may be more apt to do so in order to raise revenue
from the use of GALILEO.
In the United States, the Americans with Disabilities Act requires that municipal
transport facilities announce and display location information to passengers with
sight and hearing disabilities. This requires that both audible and visual presenta-
tions be provided. Many transit systems do not fully comply with this requirement.
Systems to provide this information automatically are attractive and low cost. GPS
enables them.
Land navigation opportunities for GPS are enormous. The incorporation of
moving maps and databases into private passenger vehicles will generate more
demand for GPS products than all other vehicle markets combined. Early
land-based adapters of the technology, of course, are the fleet operators, who can
gain significant benefits from more efficient tracking and dispatch operations with
integrated navigation and communications facilities. One concept employed is
called geofencing , where a vehicle's GPS is programmed with a fixed geographical
area and alerts the fleet operator whenever the vehicle violates the prescribed
“fence.”
The largest operator of a GPS-based land navigation service is OnStar, a Gen-
eral Motors subsidiary. In 2004, over 4 million vehicles were equipped with GPS
receivers that communicate with OnStar operators via cell phone to provide either
voice commands or map guidance to the driver.
12.3 GNSS in Surveying, Mapping, and Geographical Information
Systems
For several reasons, GPS receiver technology owes much to its early application in
the business of land surveying. The production of maps and charts and the
georeferencing of data using GPS are natural outgrowths of the accurate and reli-
able techniques developed for the land-survey market.