One runs the building. The other runs the movement between buildings. They meet at the dock door, and that seam is where most of the pain lives.
Key takeaways
A warehouse management system governs what happens inside the four walls: where a pallet is, what work has to happen to move it, and who is directed to do that work. A transportation management system governs what happens between buildings: which carrier, at what rate, on what route, on which load, and whether the freight invoice matches what was agreed.
You need both when the two problems are both expensive at the same time. You need one first when only one of them is.
Strip away the marketing and a WMS is a model of your building plus a rules engine that creates work against it. Microsoft’s own documentation for its warehouse management module describes the layout model directly: you can specify warehouse locations on any level — for example, site, warehouse, aisle, rack, shelf, and bin position — group locations by using physical capacity constraint settings, and control how items are stored and picked based on query-defined rules.
The rules engine sits on top of that model. Work templates define what work is performed, and how the work is done, and each template must include at least one Pick operation and one Put operation, while location directives direct the work transactions to the appropriate location. Capacity is enforced rather than hoped for: location stocking limits help guarantee that work isn’t created to request inventory to be put in a location that doesn’t have the physical capacity to carry the inventory.
Outbound flow is shaped by waves — wave templates help enable the outbound “Release to warehouse” process, and the sequence in which templates are evaluated decides which orders get worked first.
A TMS knows nothing about aisles. Microsoft describes the scope as functionality that lets you use your company’s transportation, and also lets you identify vendor and routing solutions for inbound and outbound orders, so that you can, for example, identify the fastest route or the least expensive rate for a shipment.
It plans in two directions. On the inbound side you can use Supply Chain Management to plan the transportation and receipt of the inbound load; on the outbound side you can plan and process an outbound load to ship specific items from a company’s warehouse to a customer. Consolidation is its own function — a load-building strategy lets you use the maximum values that are specified for height and weight in the load template.
And it closes the loop on money. Where a company uses external carriers and passes charges on, the documentation notes that you can use Transportation management to determine the transportation charges and pass them on to customers — the reconciliation step being the thing that catches a rate applied wrongly.
The cleanest way to tell the two apart is to ask which one holds which regulated record. They are not the same records, and the retention clocks are different.
The WMS side holds the inventory and traceability record. Under the Safe Food for Canadian Regulations, a food business must keep documents that trace the food one step back, by indicating the date on which it was provided to you and the name and address of the person who provided it, and one step forward, by indicating the date you provide it and the name and address of the person to whom you provide it, and those documents are kept for two years after the day on which the food was provided to you and you provided the food to another person. Where the goods are imported and stored under customs control, the record set is longer still: a bonded warehouse licensee must keep records relating to goods received and removed for the period of six years after their removal, including records concerning inventory and the transactions that occur while the commercial goods are in the bonded warehouse.
The TMS side holds the movement record. Under the federal Commercial Vehicle Drivers Hours of Service Regulations, a driver shall, within 20 days after completing a record of duty status, forward the record of duty status and supporting documents relating to that record to the home terminal, and the motor carrier shall deposit the records of duty status and the supporting documents at its principal place of business within 30 days after receiving them and keep them in chronological order for each driver for a period of at least 6 months. Cross-border, the advance commercial information must reach the CBSA no later than one hour before arrival at the first port of arrival.
A quick test
If a rule you are trying to satisfy has a driver, a plate, a border or a fuel litre in it, it is a TMS problem. If it has a lot code, a location, a licence plate pallet or a customs sub-location in it, it is a WMS problem. Very few requirements sit in both.
Take the more expensive error. If your customers are complaining about wrong or short shipments, and your counts do not agree with your customers’ counts, the money is inside the building — the WMS earns first. If your freight spend is unpredictable, your carrier invoices are approved without being checked, and drivers are running compliance on paper, the money is outside the building — the TMS earns first.
A useful intermediate step for a small operation is to keep one commercial system and buy discipline instead of software: fixed pick faces, a scanner, and a single spreadsheet of agreed rates checked against every invoice. It is not glamorous, and it will tell you very quickly which of the two systems you actually need.
The two systems meet at the dock door, and that is where implementations disappoint. Appointment scheduling, the advance shipping notice, the trailer that is on the yard but not in either system, and the difference between “shipped” in the WMS and “departed” in the TMS are all seam problems. Decide before you buy which system is authoritative for the load, and which is authoritative for the pallet. When both claim the same fact, you will spend more time reconciling them than you saved.
A Manitoba 3PL with one building and eleven customers runs a WMS and no TMS. Its inbound is customer-arranged and its outbound is parcel and a handful of less-than-truckload carriers. The WMS is doing real work: locations are modelled down to bin position, capacity is enforced through location stocking limits, and picking is directed rather than paper-driven. Freight is a pass-through billed at cost.
When the same 3PL adds a second building 90 kilometres away and starts running its own straight truck between them, the calculation changes. It now has inter-facility loads to plan, a carrier invoice to check, and a driver whose records of duty status must be kept in chronological order for each driver for a period of at least 6 months. That is the point at which a TMS starts to pay, and not before.
In both systems the same category of work is the candidate: reading documents and reconciling them. Extracting line items from a supplier’s advance shipping notice or a carrier’s invoice PDF so they can be matched against the receipt or the rate on file. Flagging the freight invoices whose accessorial charges do not appear in the agreed schedule. Reconciling the WMS shipment record against the TMS load record and surfacing the ones that disagree. Watching retention clocks — two years on traceability documents, six months on records of duty status, six years on bonded inventory records — and reporting what is about to fall out.
What it does not do is decide. Which carrier gets the load, whether a variance is a count error or a loss, and whether an invoice should be paid remain judgements a person makes and signs.
Sometimes, and the vendors sell them as modules of the same product for exactly that reason — warehouse management and transportation management are separate modules of the same Microsoft platform, with the warehouse module requiring that you create a warehouse and enable it for warehouse management processes. What matters is not whether it is one product but whether the warehouse module actually models locations and directs work.
It may hold them, but the obligation stays with the carrier. The regulations put the duty on the motor carrier to deposit the records of duty status and the supporting documents at its principal place of business within 30 days after receiving them, and no software vendor assumes that duty.
The warehouse side. Where the goods are in a bonded warehouse, the licensee must keep records describing the commercial goods when they are received into or exported from the bonded warehouse, accounting for them when they are removed, and concerning inventory and the transactions that occur while the goods are in the bonded warehouse.
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