Measuring Border Delay and Crossing Times at the U.S.–Mexico Border—Part II
Step-by-Step Guidelines for Implementing a Radio Frequency Identification (RFID) System to Measure Border Crossing and Wait Times
SYSTEM DESIGN
Key Steps for Designing the System
A general design concept of the RFID-based border crossing time and wait time measurement system is that during its trip across the border at the POE, a truck passes under two or more RFID reader stations, which include antennae. The RFID reader station detects the truck’s tag identification number and makes a time stamp of the record. By calculating the difference in time stamps, a truck’s crossing and wait times are recorded. Based on this simplistic concept, preliminary designs and detailed designs need to be prepared and need to include a description of subsystems and their functions. The detailed design includes the low-level hardware and software design for individual subsystems. The detailed cost estimate depends on the detailed design of the system. A detailed design document is also required to obtain necessary construction permits from concerned agencies, such as CBP and GSA. Key steps for designing the system are illustrated in Figure 6.
Developing Preliminary Designs
A preliminary design document needs to identify specific details of the RFID-based border crossing time and wait time measurement system that is to be deployed at the border crossing. This document needs to include maps of the POE along with flow lines, key points, and locations at the crossing where RFID reader stations are to be installed. Drawing from stakeholder meetings, the needs of the stakeholders who are to use the system should be incorporated into this document. The preliminary design document needs to address high-level capabilities defined for the system. Once the preliminary design document is prepared, it needs to be reviewed by project coordinators to assess the feasibility of successfully implementing the system. The final element of this document is a subsystem level design in which the system is broken down into its core elements and each element is described in detail.
Subsystems of the RFID-based border crossing time and wait time measurement system typically consist of a field subsystem, central subsystem, and the user subsystem. Each subsystem is functionally and technology independent of the others.
The field subsystem consists of all the deployed field RFID reader stations. The field subsystem is comprised of the RFID reader stations including the communication equipment. These stations are responsible for accurately identifying and logging the passage of commercial vehicles past a point. The field subsystem relays vehicle passage information via a telecommunication network to the central subsystem. The central subsystem logs the incoming tag information, matches the identification, determines individual crossing and wait times of trucks, and archives the data. The user subsystem interacts with the central subsystem to provide an Internet Web portal for data users (e.g., stakeholders or the public) to access current border crossing times and, if given proper credentials, to access archived crossing time data.
Subsystems for a typical RFID-based border crossing time and wait time measurement system are illustrated in Figure 7.
Developing a Detailed Design
The detailed design document builds on the preliminary design document. While the preliminary design document lays out the subsystem and conceptual design of the system, the detailed design document specifies the equipment that is needed in order to actually build the proposed system in a real-world setting. Equipment specifications for system hardware (i.e., measuring sites) and software need to be provided in this report, along with detailed diagrams of equipment that is to be installed onsite. Other considerations such as how to power the equipment need to be incorporated into this document as well.
It is important to note that before completing the detailed design document, it is essential to confirm whether the physical layout of the POE has been modified or whether there are plans to modify it. Stakeholder intent and commitments need to be reaffirmed at this point in the project, which is probably best accomplished via another stakeholder meeting. At that meeting, the interfaces between the implementation and the regional architecture (from the detailed design document) can also be validated.
Once a detailed final design document is prepared, it needs to be reviewed by project coordinators to assess whether all elements required to successfully implement the system have been identified and documented and all risks updated and addressed.
A detailed design of the RFID-based border crossing time and wait time measurement system needs to describe in hardware and software terms each subsystem identified in the preliminary design document. An example detailed design from the BOTA system included the following description about hardware assembly and installation.
Northbound commercial vehicles (trucks in Mexico destined to cross the border into the United States) pass an RFID tag reader installed at a point sufficiently ahead of the end of any queue on the Mexican export lot. The RFID tags on the trucks are read as they pass the reader station. The tag query process recovers a unique identifier for each vehicle similar to a serial number. The reader station applies a time stamp to the tag read and forwards the resulting data record to a central location for further processing via a data communication link. This reader station also time stamps tag reads and forwards the data record to the central facility. There are several options for a communication link including public and private wireless and wireline. The data bandwidth requirements for each station are not excessive and could easily be met by each of these alternatives.
Figure 8 illustrates the configuration.
Each RFID reader station has an antenna located over each lane at the location. The location of each reader needs to be chosen to limit the number of antennae required for site coverage. The antenna connects with a traditional tolling-quality RFID tag reader that can reliably read the protocol of a variety of tags carried by trucks crossing the border. The tag reader continually scans for a passing tag. It is important for the tag to be correctly positioned and under the windshield’s glass for best readability results. As a tag passes the reader’s antenna, a unique code is recovered from the tag via an exchange of radio frequency energy. The code is converted into a digital message and forwarded to the RFID reader station’s onsite data logging component. The reader’s data communication protocol needs to be such that few or no “handshakes” and additional transactions are required during normal operation (tag read mode).
The onsite logger is used to capture, time stamp, and store all tag messages (tag reads with vehicle identification code) from the reader and can also be accessed either remotely or locally if a problem in communication interrupts data flow from the site. The logger can be considered a backup to secure the vital data needed to accomplish the main goals of the project in the event of communication failure. The logger then passes data moving both from the RFID reader and toward the reader. All data coming from the reader (tag data) are time stamped and logged.
A communication solution needs to be implemented for each field location. The communication setup needs to include data transmission between the RFID reader station and the central server via cellular data.
RFID readers send data to the fixed Internet protocol (IP) address on a fixed user datagram protocol (UDP) port number using a cell modem. The UDP listener on the central server monitors the UDP port for any incoming data packets. When the UDP listener detects any data packets on the incoming port, it reads the data packets, associates a time stamp with the data read, and invokes a stored procedure on the database.
The central facility receives data from all RFID reader stations. The raw crossing and wait time data are processed by matching tag identification of individual trucks at the entrance point on the Mexican side and the exit point on the U.S. side. The difference in time stamps yields a single truck’s progression as a function of time through the POE. If more reader stations are incorporated, producing trip segmentation, a better picture of the progression can be obtained using the same technique. The tag matching process is executed periodically to obtain a reasonable sample of trucks to produce an average. The current crossing and wait time data can be made available via Internet and mobile devices.
The central facility stores all inbound raw reader station data and subsequent processed data in an archive for future access and use by regional transportation agencies and other authorized stakeholders. In essence, the central facility acts as a data center for the project and therefore needs to be located in a reasonably secure building with reliable electric service and with personnel available to provide technical support as needed.
Developing Data Dissemination Techniques
The RFID-based border crossing time and wait time measurement system works by reading unique identification numbers assigned to individual transponders. These unique identification numbers can be made anonymous by encrypting them using industry standard algorithms. Encrypting a transponder identification number before it leaves the wireless modem or other transmission devices that sends data to the central subsystem provides the highest level of security. This method also satisfies the need to make the transponder identification number anonymous before sending the data to the central subsystem. To achieve this, either a separate encrypting device has to be installed inside the cabinet or the readers themselves need to have a function to encrypt transponder identification numbers.
If ensuring data security and making the transponder identification anonymous are mandatory requirements, then the system design needs to explore these techniques. Also, appropriate steps need to be taken to safeguard the data once they have reached the central subsystem (server). This includes regular data backups to external media such as compact disks, magnetic tapes, or virtual storage facilities.
As part of the system design, techniques to provide access to raw data, aggregated data, and other charts and graphs to stakeholder agencies and the public need to be included. For example, access to near-real-time crossing and wait time data could be made available to motorists and the public in general through the Internet. Real-time information can be relayed using RSS technology, which essentially provides updated data in an extensible markup language (XML) format. Because of the open nature of the format, Web browsers and standalone applications can easily read the data. External agencies can obtain the information from the RSS site and add to their information Web sites. Similarly, regional traffic management centers or whoever else maintains the RFID-based border crossing time and wait time measurement system can use the RSS feed and display the crossing and wait time information to their field ITS devices.
Preparing a Test and Evaluation Master Plan
A test and evaluation master plan (TEMP) that describes various subsystem level and hardware/software-level tests to be performed to verify the proper operation of the RFID-based border crossing time and wait time measurement system and its components needs to be developed. These tests are intended to establish the high-level working nature of the system and also to test individual system components for specification compliance. Tests need to be performed for each subsystem and its hardware and software components. The TEMP also needs to describe techniques that are to be used to test individual devices and subsystems and the key parameters that are to be used to test against. The TEMP also needs to include how the system as a whole is to be evaluated. These key test and evaluation parameters need to be agreed upon by the stakeholders early on while preparing the concept of operations.
Identifying Operations and Maintenance Tasks
O&M of the system includes tasks required to run the system continuously to accomplish goals and objectives for which it was designed and implemented. O&M of the system needs to include tasks performed (a) daily, such as real-time monitoring of the system and data dissemination; (b) as needed, due to unexpected device failures; and (c) periodically, to repair and replace equipment.
Day-to-day tasks for operating the system include the following:
- Monitoring collection of raw data from RFID field devices and processing, aggregating, and disseminating real-time crossing and wait time data.
- Monitoring information relayed to end users through the Internet.
- Monitoring performance of the system components and troubleshooting critical system failures.
Periodic tasks to operate and maintain the system include the following:
- Repairing, replacing, and upgrading equipment, components, and modules.
- Diagnosing and resolving data inconsistencies and software glitches.
- Responding to requests from the users regarding information such as data accuracy and data query.
- Preparing reports related to information such as performance of the system and summary results.
- Performing preventive tasks such as backing up the data archive.
Maintenance tasks due to unexpected events include the following:
- Repairing and replacing field devices due to extreme weather conditions.
- Recovering archived data in the event of hardware failure and rebooting the system after power failures.
Developing a Business Model
It is important to develop a business model for the operation of the system after the implementation. During the stakeholder input phase of the project, is important to analyze willingness to develop a long-term commitment from stakeholders.
The operation of the system to provide close to real-time information needs to have staff dedicated to regularly monitor the system and make sure that it is working properly. The analysis of archived data and report development also requires staff dedicated to these activities.
It seems that the best alternative for the operation of the system is to have an independent third party dedicated to running the system. Some stakeholders from the private sector have expressed their interest in operating the system. However, most of the private-sector stakeholders are interested in one particular POE and not in the overall system. Therefore, a better option is to have a group that has no particular interests and that could independently monitor and further develop the system.
Funding for the operation could come from the border States, Federal agencies involved in cross-border transportation, and even private-sector stakeholders that use the information generated on a near-real-time basis, as well as the archived information.
Data usage and access policies and procedures along with cost of data access need to be defined in order to identify the amount of funds that are required to operate and maintain the system. Funding for system expansion is another parameter that needs to be budgeted in the business model.
Evaluation Questionnaire
The implementing agency should prepare a list of questionnaire that should be considered prior to deploying the system and ensure that the system is deployable. A recommended list of evaluation questionnaire is as following:
- Have you collected and documented current state of operation at the border crossings? This includes criteria such as physical layout and operation times.
- Have you collected baseline data, which may include total crossing times for different types of vehicles, shipments, and daily volumes?
- Will the design meet all the requirements of the system?
- Have you estimated the detailed cost of the system and the components?
- Have you prepared a detailed T&E plan? Have the stakeholders agreed to it?
- Has a budget for ongoing operations been defined and funding sources identified?
