Evaluating the Use of Electronic Door Seals (E-Seals) on Shipping Containers

E-Seal Overview

E-seals are transponders that can be used by shippers and enforcement agencies desiring to track shipments and that can also help determine shipment status and shipment integrity. E-seals can report their positions and are able to record the time that they were activated, compromised, or removed (Zhang, Liu, Yu, & Zhang, 2007; Kim et al., 2007). E-seals are electronic replacements for common mechanical container door seals (Figure 1) and use the locking bar on the container’s back door. The European Conference of Ministers of Transport, in a review of container security, noted that E-seals were an “appealing solution” for both security and processing concerns but also called for more technical standards and operational experience before the technology is mandated and concluded that a complicated hardware and software infrastructure must be developed for E-seals to be effective (2005, p. 54).

Figure 1.

Common mechanical container door seal

Different E-seal designs have been developed over the last decade and include devices that communicate by using RFID, infrared, direct contact, long-range cellular, or satellite transmissions. While each seal has its own characteristics, RFID E-seals were selected for the State of Washington test because they were a relatively mature product that showed promise for both increasing container security and reducing processing delays for cargo inspections. The RFID E-seal design involved relatively simple technology that potentially could be mass-produced at a reasonable cost. The RFID E-seal is the most common type in use today because of its reliability and ease of integration with current infrastructure (Wolfe, 2002; Le-Pong & Wu, 2004).