A rose is a rose is a rose, Gertrude Stein wrote in one of her many variations on the phrase.
If the sentiment were taken literally (and it was never quite meant to be), rose aficionados would disagree. The variations of the rose are boundless.
So too is it in our business, with the concept of on time. In our annual study of DC metrics, conducted with the Warehousing Education and Research Council, Georgia Southern University, and Supply Chain Visions, the definition of "on-time delivery" has once again proved to be elusive for researchers—and perhaps, too, for the shippers who responded to our survey.
As thorny as the concept of on-time delivery may be, the related concept of on-time shipment poses no such difficulties. Did goods leave the DC when intended? That's a yes-or-no question.
But, oh, what a slippery thing "on-time delivery" continues to be. The difficulty, it seems, is that there may be as many definitions as there are receivers. The scheduled day? Works for some. The agreed-upon day? That works, too, although I'm not sure how it's different from the scheduled day. At or before the scheduled time? Within a certain window of time? Before, but not after, a scheduled time? Up to a specific number of minutes before, but not after, a certain time?
And few are the DCs (except those serving only their own companies) that don't have multiple customers, each of which may have a different definition and each of which may have its own penalties for non-compliance.
What makes matters worse is that whatever the definition, capturing the data needed to establish whether or not shipments arrive on time has proved notoriously difficult. Shippers must rely on their customers or carriers. They may not know goods are late until a complaint arrives, followed by a costly chargeback. But that's starting to change. Carriers have gotten much better at capturing proof-of-delivery information and providing exception reports to their customers even while goods are in transit. Technology can give near-instant confirmation of a delivery in many cases. And transportation management systems are getting better at tracking compliance with the myriad demands of customers.
But still, "on time" remains harder to define and harder to measure than one might at first suspect.
Einstein posited that time slows as an object accelerates. Astronauts age more slowly, supposedly, than those of us on the ground. How that works is beyond me, but I would bet that many a shipper has wished for a way to slow the clock for shipments that head out the door—"put time in a bottle," to borrow a phrase from singer Jim Croce. Of course, too often, shipments leave the shipping dock and run right into a bottleneck on the highways—not exactly what any shipper hopes for, and often putting the goal of on-time delivery, whatever it is, out of reach.
The issue of time has been at the core of logistics from, yes, time immemorial. It's why the Department of Transportation—as opposed to, say, the Department of Commerce or Energy—makes the annual announcements about when daylight savings time will begin and end. Renaissance governments invested in observatories not so much to explore the heavens as to determine ways of accurately gauging time. Knowing the time was essential to deep-water sailors in order to determine longitude, and failure to know the time led to many a shipwreck. One apocryphal story (much disputed, but I like it anyway) suggests that the phrase "on the ball" originated in reference to alert shipboard navigators, who watched for the time ball at the Greenwich Observatory to drop in order to set their chronometers for the outbound voyage.
Time measurement eventually became pretty definitive (at least until Einstein came along) and intimately connected to transport. But on time? Well, what that means is, to borrow one last time from the good physicist, relative.