Sign in

Blog · Board and management reporting · Shipping and logistics

Transit reliability on ten shipments: the whole arithmetic on one page

The complete transit time reliability calculation on ten ocean shipments for one customer on one lane, small enough to check by hand: quoted transit at booking, departure, arrival and delivery milestones, actual door-to-door days, the tolerance, on time per shipment, reliability, the interquartile variability, the delay split into origin dwell, on-water and destination dwell, the shipment with milestones out of sequence, and the assertion that every delivered shipment has a delivery milestone after departure, so a reader can reproduce every figure and then run it on their own milestone data.

By CoviragePublished 17 September 20263 min read
The short answerTen ocean shipments, one customer, one lane, quoted at 28 days door to door with a tolerance of four days late. Actual transit is delivery date less booking pickup date from the milestones. Six of nine measurable shipments arrive within tolerance: reliability 67 percent. The interquartile spread of actual transit is 11 days, from 27 to 38. Of the late days, most sit at destination: the delivery milestone comes long after arrival. One shipment has a delivery date before its departure date, fails the assertion, and is excluded with a count. Every number can be reproduced by hand.

Transit reliability is a comparison per shipment and a spread, and on ten shipments it can be worked by hand, with the delay split and the bad row. This page works actual transit, on time, reliability, variability, the split and the assertion. Quoted transit: 28 days. Tolerance: up to 4 days late.

The milestones

Shipment Pickup Departed Arrived Delivered Actual days Within 32?
1 1 Jun 4 Jun 24 Jun 28 Jun 27 Yes
2 3 Jun 6 Jun 26 Jun 3 Jul 30 Yes
3 5 Jun 9 Jun 30 Jun 13 Jul 38 No
4 8 Jun 11 Jun 1 Jul 6 Jul 28 Yes
5 10 Jun 13 Jun 4 Jul 18 Jul 38 No
6 12 Jun 15 Jun 5 Jul 10 Jul 28 Yes
7 15 Jun 18 Jun 8 Jul 14 Jul 29 Yes
8 17 Jun 20 Jun 10 Jul 18 Jun −1 Assertion fails
9 20 Jun 23 Jun 14 Jul 21 Jul 31 Yes
10 22 Jun 25 Jun 16 Jul 27 Jul 35 No

The assertion

delivered milestone after departed milestone, for every delivered shipment

Shipment 8's delivery date, 18 June, precedes its departure on 20 June. Listed; excluded. Nine measurable shipments.

Reliability

Reliability = shipments within tolerance ÷ measurable shipments = 6 ÷ 9 = 67%

Within 32 days: shipments 1, 2, 4, 6, 7 and 9, six of nine. Reliability 67 percent, against 92 percent on this customer lane last year.

Variability

Actual days sorted: 27, 28, 28, 29, 30, 31, 35, 38, 38.

25th percentile ≈ 28; 75th percentile ≈ 35; interquartile spread = 7 days

Last year's spread on this lane: 3 days.

The delay split

Quoted stage shares: origin 3 days, on water 21, destination 4.

Shipment Origin dwell On water Destination dwell Late days Stage over
3 4 21 13 6 Destination: +9
5 3 21 14 6 Destination: +10
10 3 21 11 3 Destination: +7

All three late shipments ran over at destination. Origin and on-water are on quote. That is one port, one agent, one conversation.

The customer view

Lane Shipments Reliability Last year Spread Last year Delay at
This lane 9 67% 92% 7 days 3 days Destination

The customer is already re-tendering this lane. The forwarder now knows why, and where.

Where it goes wrong, even at ten

Shipment 8 counted. A two-day ocean transit; reliability reads 70 and the mean transit falls.

Mean transit reported. 31.6 days, near the quote; the spread is where the shipper's pain is.

Lane-level reliability. The lane across all customers is at 85; this customer's nine shipments are at 67.

No delay split. The forwarder promises to do better; the destination agent is never called.

From ten to ten thousand

The same milestones per shipment, per customer lane, per quarter, with the assertion first. Covirage runs it on the shipment and milestone exports. The transit reliability guide covers the measure, and the detention and demurrage guide covers what destination dwell also costs.

Questions people ask

Why interquartile and not the mean?

Because the shipper plans inventory around the spread, not the average. Ten shipments averaging 30 days with a range of 24 to 44 need far more safety stock than the same average between 27 and 33. The 25th to 75th percentile is the spread most of the shipments fall in.

How is the delay split?

From the milestones: pickup to departure is origin dwell, departure to arrival is on water, arrival to delivery is destination dwell. Each is compared to its quoted share, and the late days are attributed to the stage that ran over. On this lane it is destination.

What happens to the out-of-sequence shipment?

It is excluded from reliability and listed. A delivery milestone before departure is a data error, usually a wrong date keyed at the destination agent, and the row is fixed at source rather than counted as a two-day transit.

Related reading

Board and management reporting · Shipping and logistics

Booking-to-invoice cycle per customer: the days revenue waits

How a forwarder measures the time from shipment delivery to invoice issued, per customer and per branch, from the shipment milestones and the billing ledger: the median days, the shipments delivered and still unbilled past a stated age, the value waiting, the branches and customers where the cycle is longest and why, disputed accessorials, missing carrier costs, customer billing rules, and the working capital the delay ties up.

16 Sept 20263 min readBoard and management reporting · Shipping and logistics

Customs holds per customer: the entries that stopped, and the data that stopped them

How a forwarder or customs broker measures customs exceptions from its entry data: entries held per customer and per lane, hold rate against the broker's own norm, days held, the reason codes, the share caused by the customer's own data, missing commodity codes, wrong values, incomplete descriptions, against the share caused by the broker or the authority, the cost in storage and delay, and the customer conversation about the fields that stop their freight.

16 Sept 20262 min readBoard and management reporting · Shipping and logistics

Detention and demurrage per customer: the charges that leak and the customers that cause them

How a forwarder or carrier measures detention and demurrage from the container event data and the billing ledger: free time against actual dwell per container, charges incurred from carriers and terminals, charges billed on to customers, the gap between the two per customer, the customers whose containers routinely exceed free time, and the identity that ties charges incurred to charges recovered plus absorbed.

16 Sept 20263 min readBoard and management reporting · Shipping and logistics

Ten questions a forwarding managing director asks, and the table that answers each

The ten questions the managing director of a freight forwarder puts to the branch and trade lane managers, what is lane share per customer and per mode, are TEU and kilograms ever added, which customer lanes lost reliability before the tender, what detention and demurrage did we absorb and for whom, how long does delivered freight wait for an invoice, which customs holds are the customer's own data, which customers are concentrated on one carrier, what is margin per file by branch, which customers went quiet by lane, and what changed, each with the table from the bookings, milestones and billing exports, and the answer to send back.

16 Sept 20262 min read