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Back To Basics - The Next Step

In our previous "Tolling - Back to Basics" feature we looked at what makes up the lane infrastructure and how to gather vehicle data and information so that the correct toll fee may be collected. In this feature we'll look at what happens to that information and the process trail from initial vehicle detection to the "green light for go".

By installing electronic toll collection (ETC) systems, government agencies believe that traffic will move faster thereby reducing traffic congestion and emission fumes from queuing traffic - all good news for the environment and the road user. The idea is that even if commuters have to slow down for the toll booths, they can pass through faster using ETC. In several European countries and states across the USA where the most technologically advanced ETC systems have been installed, motorists no longer have to worry about stopping to deposit or hand over the toll and there is certainly no searching the car for loose change that's slipped down the back of the seat! As long as they have a transponder and an account in credit, motorists just have to rely on the lane antenna to read the signals from their transponder to see them on their way.

Here are the basic components that make up the ETC system:

  • Automatic Vehicle Classification system (AVC):
  • The system that detects & determines the type of vehicle passing through the plaza.
  • In-lane antenna:
  • To read the vehicle account data.
  • Vehicle transponder :
  • Containing the vehicle account data.
  • Lane controller:
  • The computer that monitors the lane equipment and updates system operations.
  • Violation Enforcement System (VES):
  • Captures the images of vehicles in violation of payment.
  • Host and Plaza Computer:
  • The Host is a repository for all the lane information. The Plaza consolidates all the transaction information from all systems.
  • Central Administration Computer (CAC):
  • The CAC handles all the customer operations such as enquiries and accounts.


How the system works

  1. As a car approaches a toll plaza, if there is a transponder on board it is activated by the radio-frequency (RF) field emitted from the antenna.
  2. The transponder broadcasts a signal back to the lane antenna with some basic information.
  3. The vehicle passes through the classification zone where vehicle data is collected by the AVC.
  4. Transponder & vehicle data information is transferred from the lane antenna & AVC to the lane controller for processing to determine validation. The transponder information is matched with the vehicle classification information. The transaction is either valid or invalid.
  5. If it is valid (the classification and transponder information match) then the lane controller authorises the transaction for processing.
  6. The customer account, if in credit, is then debited.
  7. The new balance for the account is passed to all plaza computers to ensure accounts are kept up to date.
  8. An invalid response generates a violation process. This is a separate process altogether. All lanes are monitored using video cameras for violation purposes. If you try to go through a plaza without a transponder, paying the appropriate fee or by evasion using the hard shoulder, the camera records you and takes a picture of your license plate. The transaction is then processed and the vehicle owner receives a violation notice in the mail.
  9. Once the transaction is complete the customer may proceed on their way. In most ETC systems the driver is informed to proceed by a green light, raising of a barrier or message signs.


So the entire transaction process takes a matter of seconds to complete. The electronic system has recorded each toll transaction, including the time, date, plaza and toll charge of each vehicle.

ETC has certainly increased the traffic flow at plazas and has been proven to reduce vehicle congestion, a prime example is the USA's New Jersey Turnpike Authority's Exit 1 in Carneys Point Township where previously common place 30 mile queues at holiday times are now a thing of the past due to open road tolling (ORT) and ETC. In fact with modern day ORT it is possible to pass through a plaza at highway speeds. However, the rules regarding how fast you can travel through an ETC plaza differ from system to system, speeds varying from anything as slow as 5mph (8kph) up to 55mph 86kph).

Lane Controllers

When a vehicle passes through the classification zone data relating to that vehicle is generated by the lane infrastructure. This vehicle data then requires collecting and processing. Most early ETC solutions employ a lane controller computer for each toll lane to handle these processes. At the same time the lane controller accepts inputs from operator consoles and displays, performs calculations, records data and communicates with plaza computers. It is this complex messaging that is so vital to the smooth operation of a toll system. Modern day lane controllers have simplified many of the lane processes and forwarding of information. They are now more ''user friendly'' and may be used in a variety of toll lane types from manual to ORT. In some cases systems designed for multi-lane tolling have developed multi-lane lane controllers, reducing the need for one lane controller per lane. A good example of this is E470, Denver Colorado, where Diamond Consulting Services Ltd implemented the Idris® technology into the tolling system to enable the same architecture to be used across all lanes types.

With the progression of lane controllers has come an increase in functionality and capability.

Lane controllers now provide extensive support for Automatic Vehicle Identification (AVI) lanes used by vehicles with on board transponders, and all payment modes (electronic, cash, manual/ attended, and equipment combinations). Transaction records are kept on the lane controller for 30 days, so if any equipment fails the transaction record isn't lost. This collated data from the lane controller is then passed to the plaza computer.

On Board Transponders

Where vehicles with on board transponders pass through the toll plaza the lane controller searches its database to make sure that the vehicle identification number is for a valid account and that there is enough money in the account to pay the toll. The system must also ensure that the tag read is for a valid vehicle. ETC systems using the Idris technology are able to correlate the tag read and the automatic vehicle classification information to confirm that a tag read for a car is actually situated within a car and not within a heavy goods vehicle. If everything is OK the lane controller in effect waves the car through, in the case of ETC, a green light flashes or a barrier is raised.

The lane controller then updates a computer at the toll plaza, which in turn updates the systems main customer administration computer with all relevant transactions. If the lane controller doesn't find enough money in an account or simply does not receive any data because the car doesn't have a transponder, it immediately issues a command to save the images taken by 2 cameras of the license plates of the vehicle. (All vehicle license plates are photographed but the images are only saved if there is a problem.) The digitised video images are sent electronically to the customer administration centre and a toll violation notice is issued.

Legal and Technical Criteria for Payment Enforcement

The payment enforcement system must meet legal and technical criteria specific to each country and region. The legal criteria would include all legal procedural and record keeping requirements as well as those related to admissibility of evidence in court (i.e. in case vehicle violation tickets are contested). The technical requirements are related to the accuracy of the violation detection, capture and notice issuance system.

Plaza & Host Computer

This is where all lane data is consolidated. All plaza computers are networked using a Local Area Network (LAN) and the data information is transferred from location to location via this high speed communication method. Plaza computers may have to deal with a network of 200 or more lanes, that's 200 physical lines of communication.

The plaza computer, in an ETC system, provides information to the plaza supervisor and allows the supervisor to monitor the activity of the toll plaza. The plaza computer is linked to each lane controller computer at the toll plaza and also linked to a central administration computer.

Central Administration Computer (CAC)

The CAC receives information from the plaza computer. All of the toll plaza LANs are connected to the CAC via a Wide Area Network (WAN). The plaza computer will normally be connected to the CAC at all times in order to maintain current information from each plaza and thus enabling continuous monitoring of all the plazas. Should CAC be disconnected from the plaza computer, the plaza computer stores the information until the connection is re-established.

The CAC can be located in the toll road operators office for access to the data on both a "real time" and "record and view" basis. This allows road operators to cross-reference traffic volumes and classification data against collected toll revenue. These measures pro actively discourage any conspiracy to defraud by means of data manipulation before reporting the results through conventional channels, thereby maximising revenue.

Environmental Issues

It is essential that these computers are "fail safe", they may be handling over 1 million transactions per day, this doesn't leave room for error or power failure! The systems need to operate without interruption. This is why USA based company's like Electronic Transaction Consultants (ETC) who developed the innovative RITE® Solution and ACS State & Local Solutions that operate Vector Express have tolling solutions that offer the complete package. Both systems offer full system redundancy, immediate change overs, UPS on all plazas and generator back up in case the power is out for several days. Tolling system computers require clean power without surges or voltage spikes and this is where the system integrators have developed both their hardware and software solutions into a unique environment.

User Privacy

One of the most frequently voiced concerns over ETC systems is the user privacy issue. Initially planners were concerned that the general public would reject ETC for fear of having their movements recorded by the government. By and large, in the USA and other European countries, this appears to not be a problem for existing systems. In fact, it has been noted in road user surveys that several motorists prefer methods of payment that are not anonymous, such as credit cards. However, this should not be construed as meaning that patrons are indifferent to having information about their travel released. Toll agencies find that they must protect themselves, and their patrons, against unauthorised use of account information. Besides ensuring the security of all data transfers, toll agencies find it useful to draft legislation prohibiting the use of patron travel information for purposes other than toll collection and enforcement.

Interoperability

Interoperability is becoming more important as ITS technologies develop. There are, in general, two areas, technical interoperability and an administrative component. Technical interoperability means that different types of transponders should be able to communicate with the same roadside reader and that a single transponder could be used across multiple ETC systems. This is especially relevant in Europe with traffic passing through many different countries on a single journey. In addition, different lane architecture should be compatible with other supplier components, thereby enabling a "plug & play" nature and System Designers the freedom to select the most appropriate solution for their system. Administrative interoperability (also called procedural and contractual interoperability) means that charges made on one system can be deducted on another system's account, regardless of state, country or location. The use of smart-card based ETC systems in particular requires coordination not only among toll agencies, but also among vehicle rental operators, public service vehicles, parking providers, and even communication companies.

So the development of ETC has brought with it improvement for the environment, reduced congestion and gives back to the road user "time"! However, in a fast paced world, technology moves at open road speeds and it would seem that many road operators are looking at this form of road user charging as the future of tolling. ORT is the next logical step from ETC, but with it comes a whole new bundle of technical challenges - and we'll keep those for the next article!