Continuous vs. Choke-point Tracking of Assets and Loads

Which Approach to Using RFID to Track Mobile Assets is Right for You?

Abstract

The article discusses the use of RFID for tracking mobile assets and loads in the supply chain, comparing two alternative approaches: continuous tracking and choke-point tracking. It highlights the attributes, advantages, and disadvantages of each method, providing insights for companies to make informed decisions when selecting the appropriate tracking approach for their specific needs.

Article

The use of RFID for tracking mobile assets and loads, such as semi-trailers, shipping containers, and tankers can provide visibility into delays much earlier in the process, giving a company many more options in how to respond. In addition, tracking containers and loads with RFID can reduce shrinkage and demurrage charges, and increase utilization of these expensive assets.

There are two quite different alternative approaches available to track assets across the supply chain with RFID:

  • Continuous Tracking – Typically a GPS device attached to the asset, periodically transmitting its location via a satellite or cellular link. These are often coupled with a conventional RFID device. However, even if it does not contain a conventional RFID device, it is a form of RFID because the device transmits an ID over the satellite or cellular RFID link and the receiving software uses the ID to distinguish one asset from another.
  • Choke-point Tracking – An RFID tag on the asset is read when the asset passes through “chokepoints”, such as when entering or leaving a container yard, loading or unloading from a ship, entering or leaving a DC, going from the back of the store to the front of the store, etc.

Either of these may include various sensors (temperature, shock, etc.) that record environmental conditions. Each approach has its advantages and disadvantages and differences, which should be considered when selecting the optimum approach:

Attribute

Continuous Tracking

Chokepoint Tracking

Cost of Device

Higher device cost, because it must include GPS plus Satellite and/or Cellular communications.

Lower device cost, it only needs a tag.

Cost of Infrastructure

Lower because there is no need for a network of readers at thousands of chokepoints throughout the supply chain.

Higher – must have networked readers at all key chokepoints.

Ongoing service costs

Higher – must pay Satellite and/or Cellular link fees.

Lower – must pay network costs, but don’t need satellite link.

Near-real-time location Visibility

Yes – depending on interval of update, you can know within a few minutes accuracy of the current location.

No – You don’t know until arrival at the next chokepoint. However, in reality, virtually all ships and now increasing numbers of overland vehicles allow you to check on their location, so you can have visibility by association of the asset with the vehicle carrying it, provided those systems have been integrated.

Near-real time condition and event monitoring

Possible – If the device includes temperature, shock, intrusion, and other sensors, then an alarm can be generated and corrective action taken.

No – Sensor devices are only read at the choke-points or end-points, so in general only “after-the-fact” notification is possible.

Route flexibility

High – The vehicle/asset can travel virtually anywhere on the planet, on any route, and still be tracked.

Lower – You are constrained to tracking only routes through ports and facilities that are outfitted with readers. Today these are quite limited, but as time goes on more and more chokepoints will be instrumented with RFID readers.

Geofencing*

Yes—provided route monitoring software supports it.

No.

Multi-modal

Yes – Can track a container as it is transferred from trailer to ship to rail.

Only to the extent there is instrumentation of the various modes, with readers at chokepoints.

RTLS (Real Time Locating System) capabilities

Yes – within accuracy limitations of GPS.

Not included – In most cases you will need a separate RTLS system.

Visibility to items, shipment info, and contents of asset

Either the tag must have enough memory to hold information about the contents (e.g. some active tags for use on containers hold the entire manifest) or the software must be sophisticated enough to associate the contents with the asset ID.

Same as Continuous.

Federated software model

The mindset of continuous asset tracking providers tends to be “we’ve got you covered, end-to-end”, so they are less likely to see a need for a federated software model supporting hand-offs between independent domains.

My its nature, choke-point solutions need to be architected to enable multiple instances run by different organizations to be integrated in order to provide end-to-end visibility. For example, Savi is architected like this.

Given the differences between the two approaches, what should you think about when selecting an approach? Here are some things to consider:

  • Real-time Tracking: How critical is near real-time tracking for you? Do you need to know up to the minute what’s happening with each load? Perhaps you have a problem with theft of vehicle loads … in that case you may want to implement geofencing. Or you may have a problem with spoilage of high value goods due to temperature excursions and want alerting when the problem is occurring, not afterwards.

However, you must also ask yourself what you would do with that data if you had it. Do you have the infrastructure to filter that “fire hose” of data and just pull out the important exceptions? Then do you have the ability to make sense of and respond to those alerts? Can you act on the information? For example, if you get an alarm that one of your in-transit refrigerated units is above the allowed temperature range, do you have the ability to correct it?

  • Nesting: If you need real-time tracking, you may be able to get it if you are receiving vehicle location data from your carriers. You will need nested-visibility capabilities that integrate that data with the tracking of loads and containers being carried.
  • Choke-point Reader Network: If you are considering the choke-point tracking approach, ask the provider about their current and future reader network. Does it cover the chokepoints that are critical to you now and in the future? If you are a large customer, you may be able to influence the expansion plans of your provider. Some providers are partnering with other networks to provide extended coverage. You may be able to leverage multiple networks.
  • Route Flexibility: How important is route flexibility? Is it essential that you can track into areas where a reader infrastructure is not available? Or is your traffic limited to routes that are covered?
  • RTLS Needs: Do you need RTLS (Real-time Locating System)? For example, do you have a need to find containers in large yards? Is this something your 3PL or carrier partners can leverage? If so, then continuous tracking may provide a double benefit for you.

These two approaches can be combined, as Savi Technologies has done with its Comtech Mobile Datacom partnership. In fact many of the continuous tracking devices also contain conventional RFID capabilities. Ultimately this hybrid approach may provide the best of both worlds, albeit at a higher cost.

Of course there are many other tradeoffs to consider in selecting a vendor and solution, such as total cost, stability of the company, how well they know your industry, etc. Companies that want to track their valuable assets using RFID have a choice to make, and should make it wisely, considering all of their needs and capabilities.


* Geofencing is the ability to draw an imaginary fence around the expected route of the vehicle and then generate an alarm if the vehicle goes outside the “fence”. This can be useful for detecting vehicle theft/piracy as well as keeping drivers from taking the wrong route (intentionally or unintentionally).

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