Scaling the Technology

The technology needed to support broader use of targeted tolling and pricing, and even to implement comprehensive pricing, is largely available today. In fact, the demands of modern toll roads have led to the development of new tolling technologies in recent years that facilitate dynamic pricing and open road tolling with no toll booths and declining collection costs. In addition, the cost and functionality of on-board GPS units have evolved to the point where they could facilitate the implementation of comprehensive pricing. The major limitation is that current commercial-grade systems cannot reliably determine which lane a vehicle is in, which places constraint on a concept with variable lane pricing (e.g., for HOT lanes) that does not also include some additional infrastructure. Next generation GPS satellite systems, however, could solve this problem. A second issue is that GPS reception can be lost or can produce "multi-path" effects in urban areas with high-rise buildings. Further research is needed to understand the extent of these problems and possible solutions.

Today's electronic toll collection systems largely rely on in-vehicle transponders, which are "interrogated" by antennas mounted on overhead gantries. Since their introduction, the cost of toll-related transponders has declined consistently, to the point where $6-10 "sticker tags" are now being increasingly adopted to replace older $20 battery-powered tags.87 A few toll systems, beginning with Toronto's Highway 407, offer the option of video tolling, in which the license plate number is videotaped and automatically read. To provide universal access (meaning a user does not have to subscribe to a system), the video tolling system must have access to relevant motor vehicle databases to create a bill. Most video tolling systems, however, require prior registration (or timely after-the-fact notification by the user, to avoid a fine). These systems have a low in-vehicle cost but relatively high roadway costs, especially in systems that charge per mile, in which case every entry point and every exit point must be equipped with gantries for the transponder antennas and for video enforcement (and possibly tolling) equipment.

It is generally agreed that equipping all roads everywhere with the types of equipment used in current electronic toll collection application would be far too costly. Instead, most concepts for comprehensive pricing assume the use of an on-board unit consisting of a GPS receiver, software, and a wireless communications capability. Such a transition would be easier and cheaper if the functional elements of such OBUs were mandated by the federal government prior to a decision about replacing fuel taxes with VMT charging, perhaps under the auspices of the Vehicle Infrastructure Integration effort, which has been under way for a number of years among the FHWA, various state DOTs, major auto companies, and equipment vendors. For example, pricing technology could be implemented in conjunction with a program such as lntelliDriveSM (formerly known as the vehicle infrastructure integration program). IntelliDrive, as envisioned, will support secure communication between the vehicle and roadside to support mobility, traffic management, and traveler safety.88