Radio-frequency identification, or RFID, has found widespread application in the business of logistics, helping to track and regulate the complex movements of both cargo and humans. RFID in the transportation sector has succeeded because of, in part, cooperation among stakeholders in setting protocol standards.
(RFID) has found many applications within the transportation sector, from trucking to airports, and from rail to shipping. As is true for an early-stage technology, once it works in one application, clever engineers start to identify other applications to develop, thereby leveraging the investment of the first application. Following is the state-of-the-industry of RFID in transportation.
One of the earliest implementations of RFID in the trucking industry was the experimental CRESCENT program on the West Coast. CRESCENT was a trial application to allow trucks to bypass weigh stations. The goal was that, as a truck approached a weigh station, it would be weighed via a weigh-in-motion system. The vehicle's RFID tag would be read and the pertinent data reviewed (safety, taxes, weight, etc). If the vehicle met all the standards required, a signal was sent to the vehicle allowing the station to be bypassed.
The savings to the trucking companies was significant because vehicles did not have to slow down and then accelerate again to highway speeds. While only a few minutes were saved for each bypass, the accumulated savings were significant. States also saved manpower by concentrating their inspections on carriers that did not meet the more stringent standards. The program was highly successful and has since been implemented in more than 30 states. A common RFID tag was developed so that vehicles didn't have to have separate tags on their windshields for different weigh systems.
The CRESCENT program got trucking companies thinking about other business needs that could be addressed with RFID. One application was gate operation. Before RFID, a driver had to stop at the inbound/outbound gate to be identified and to submit certain information such as mileage, fuel levels, and vehicle and trailer ID. RFID tags were developed that allowed data to pass from the vehicle via a J-bus protocol. When coupled with tags on the trailer, all of the required data could be automatically captured and transferred to the corporate database.
Other gate operations that could be accomplished were capture of the arrival/departure time and verification that the tractor/trailer combinations were correct. Some companies went on to include readers at fueling depots, allowing the authorization and tracking of fuel consumption on a vehicle-by-vehicle basis.
Air travelers are all familiar with the congestion problems at the curbs of airport arrival/departure areas. The drop-off/pick-up areas are shared by passenger cars, taxis, buses, and courtesy vans. Some airports have implemented control of vehicle traffic by tagging taxis, buses, and vans and then checking the amount of time or number of trips each vehicle makes. By charging a fee for excess trips or wait time, airports have been able to free up curb space and reduce congestion.
While studying the congestion problem, some airports noticed that there were lots of local toll tags on vehicles that came to the airport. In many cases, a tagged vehicle stayed in the parking facility for the duration of the traveler's trip. This discovery led to airport parking authorities reading the RFID toll tags to reduce staffing at the exit booths and improved service for travelers.
The Association of American Railroads (AAR) has a major logistical problem: knowing where the cars belonging to any particular rail company are at any given time.
A train assembled in upstate New York may pass through several yards while progressing from East to West. In each yard, the train makeup can change as cars are dropped and added. Once a car enters the system, the owner may not see it again for months or even years, but it will be in use by other railroads.
The first solution to the asset identification and tracking problem was the use of bar codes painted on the sides of the railcars. Bar code readers were placed at strategic locations in an attempt to read car IDs as they passed the reader. That led to two major problems. First, the cars collected dirt that obscured their bar codes and second, snow proved to be just as opaque as dirt.
In the early 1980s AAR decided to move to RFID as a possible solution. Each asset was tagged with two tags, one on either side of the asset (to not have to worry about the orientation of the rail car). All rail companies were given a period of time to tag their assets, after which if an asset was found not tagged, it was tagged by the local rail company and the cost was billed to the car owner.
Some special tags were needed, such as a high-temperature tag for coal carriers. There are instances where a coal carrier has been exposed to the elements to the point of becoming a frozen-solid chunk of ice, snow, and coal. When this happens the entire rail car has to be heated to melt the contents prior to unloading.
Other applications were investigated, such as trailer tracking and container tracking, but they were never implemented due to the inconsistencies in tag protocol and placement on the various units being hauled.
The shipping industry has been the slowest part of the transportation sector to implement RFID technology. While the U.S. military has required some use of the technology to identify high-value containers within a storage facility, RFID in shipping has a number of obstacles that have to be overcome before a general implementation can take place.
For example, on a container ship with containers stacked five high, six across, and two dozen end to end, where do you put the tag to be read? Similarly, when loading and unloading, most frequently the container is handled by an overhead crane but moved within the dock facility by a straddle carrier. Again, where do you tag the container such that all of these handling devices have RF access?
The railroad industry faced a similar set of questions when looking at the possibility of tracking container shipments on rail cars: where to place tags in relation to the track reader locations? These questions have to be answered before the shipping industry can take a general approach to the use of the technology, and then there has to be a consensus among shippers for it to be successful.
The acceptance of RFID within the toll industry has been a major factor in the success of the technology. Built upon early success stories on a bridge in San Diego, another in New Orleans, and a toll road in Dallas, RFID has become widely accepted where toll roads have been implemented.
One of the most challenging initial problems for acceptance of the technology was the multitude of tag protocols, with each vendor guarding its implementation secrets. With different systems in San Diego, New Orleans, and Dallas, the problem was not viewed as particularly significant since common users were not that high. Even when Oklahoma designed its six new toll roads, the requirement that the tag have a common protocol was non-existent -- again, there were too few common users. The only common requirements for the tags and readers were that the read speed had to be high enough to allow high-speed bypasses, the read had to be accurate, and multiple tag reads had to be minimized.
The multiple protocol problem came to a head when the consortium of toll departments in the Northeast began to consider RFID as a possible solution for the congestion drivers were suffering at the various bridges, tunnels, and toll roads. In this case, there were thousands of daily commuters crossing state lines, different toll authorities, etc.
A common protocol was a primary concern for the system's acceptance (along with the development of data inter-change protocols between the authorities). With normal RFID vendor reluctance to divulge proprietary information, the implementation in the Northeast gained acceptance slowly. In some cases, vendors licensed their protocols to other vendors. In other cases, a vendor developed dual protocol tags to enable its product to be used in multiple applications. The problems were solved eventually, and today there are tens of thousands of RFID transactions in the Northeast corridor using a common tag protocol.
In general, the transportation sector is a success story in the implementation of RFID technology across the board. While trucking and tolls have been the major players in that success, other facets of the sector are making inroads, as well.
This article was originally published on Engineering.com and is adapted with permission. For more stories like this please visit Engineering.com.