Introduction

To analyse the efficiency and utilization of the equipment fleet it is essential to know the historical and the current stock levels in the depots and terminals. Furthermore, by knowing the expected demand (i.e. forecast of import and export events) and planned empty container positioning (i.e. OTTs), it is possible to project what the stock will be in the future. This page describes how ROCK calculates and manages stock, including a set challenges and design decisions to handle them.

Types of Stock

There are three types of stock calculations used in ROCK, with different calculations and problems, but at the same time shares a couple of stock principles.

Historical Stock

Equipment planners depend on past stock levels to assess utilization of the equipment fleet, including compliance against target stock levels and analysis of stock trends. One challenge with calculating historical stock, is that equipment moves are sometimes inserted into RKEM, far into the past, or old moves are updated. To ensure that the stock history is always aligned with the latest moves history of every container, the RKEM Processing (CDS) includes measures to ensure a full recalculation is applied when relevant.

Current Stock

The current stock specifies the container count right now, in every depot and terminal. These numbers are particularly important, as they are used as the starting point to project what the stock will be in the future. The current stock is maintained and updated continuously throughout the day, as part of the batch job described in the RKEM Processing (CDS) process. Like the calculation of historical stock, this approach is also in alignment with the full moves history of each container.

Projected Stock

The projected stock specifies the stock of a future day and is calculated based on an extensive logic with multiple data inputs and operational considerations. The primary inputs of the calculation is the current stock, the expected demand forecast (i.e. import/export forecast) and planned OTTs. As inputs to the projected stock calculation is constantly changing, the stock projection formulas are applied on-the-fly in ROCK, as reports are being generated (see for example SPM Port View). The projected stock is explained in greater detail in topic Projected Stock.

Stock In Transit

When a user pulls a ROCK report that includes stock data and if the selected geo level is pool or higher, then ROCK is able to calculate and show stock in transit. The stock in transit defines all the empty equipment at a given time that is not currently gated-in. The stock in transit can be used as an additional perspective to understand the stock level compliance and stock availability.

By default the report will show the historical/current/projected stock level as a SUM of the stock for each depot or terminal. By enabling SIT in a report, the stock level will include any additional units to the stock level, effectively increasing the stock numbers. As an additional step, ROCK calculates the average SIT for each geo, which represents the "typical" SIT situation, and adds this number to the target stock level. This is done to make more fair conclusions on stock compliance, as stock+SIT is compared to target stock+average SIT.

When a users clicks "Include SIT" in a report, such as the Stock Performance Graph, ROCK will add the relevant SIT number on top of the stock levels, and the relevant Average SIT number on top of the target stock levels.

Stock in Transit calculation is described in greater detail in the Calculating Stock in Transit.

Design Principles

The stock calculations have to deal with some challenges that each require a specific design decisions to handle accordingly. Some challenges are cross-cutting over each type of calculation, while some challenges are limited to the stock projection logic. The cross-cutting principles to handle these challenges are described below. Further to below, the stock projection calculation includes additional challenges, and the related calculations are described in another dedicated section.

Stock Challenge	Description and Principles
Opening Stock and Time Zones	As equipment will naturally enter and leave the stock of depots and terminals throughout the day, the stock will constantly increase and decrease. To simplify reporting, stock is understood as the "Opening Stock" and the "Closing Stock" of every day. The "Opening Stock" is captured at 00:01, which simultaneously corresponds to the "Closing Stock" of the previous day. This principle is used in every screen in ROCK, except when showing todays stock. In this case, the current stock is shown instead, as it is more relevant and precise. Furthermore, due to shifting time zones throughout the world, the daily operations start and finish at different times, even within the same country (e.g. US mainland has three different time zones). To make opening stock numbers useful at a local level, the opening stock number to a site is always captured at 00:01 against the local time. Consequently, this introduces some discrepancies in the numbers, when assessing total stock across a geo selection (e.g. global opening stock of a day) spanning multiple time-zones. However, as the historical stock does not impact the the daily tasks of equipment planners, this approach is an accepted compromise.
Container Condition	Containers can be classified as either sound, damaged and total loss, following container condition classification as described in RKEM Mapping. When calculating and showing the historical and current total stock in ROCK, the number shown will disregard containers that are "Total Loss" and include only containers in state "Sound" and "Damaged". The "Total Loss" numbers are kept separately and some screens in ROCK will still show the Sound/Damaged/Total Loss split where relevant (e.g. see SPM Port View). For projected stock (i.e. the future), it is not possible to assess what the distribution will be between sound and damaged. As such, projected stock only includes a "total" stock value.
Stock in Transit	When pulling a report that shows the total stock within a geo selection of multiple sites, it is relevant to also consider any empty equipment that is currently being positioned within the geo selection, i.e. stock in transit or "SIT". This equipment is relevant because it is still ready to be used by customers, despite not being available at a specific depot or terminal yet. Calculation of SIT is done based on the OTTs, and uses a very similar approach to capture SIT for historical stock (past SIT), SIT for current stock (current SIT) and projected stock (future SIT).
VSA containers	VSA containers are not counted in stock. If EquipmentOwnerType in RKEM = VSA, then the container is not counted in current or past stock

A summary of the approach used to handle each of the stock challenges are described in the below table.

Stock Challenge	Historical Stock	Current Stock	Projected Stock
Opening Stock and Time Zones	Opening Stock to a past day is captured in the back-end of ROCK as the opening stock at 00:01 local time.	The stock figure displayed for Today in any screen reflects the current stock of ROCK	Stock to a future day is calculated as the expected opening stock at 00:01 local time. This is calculated based on expected demand and planned positioning. See also the dedicated section for projected stock.
Stock In Transit	Past SIT = Stock yet to reach destination site by local time 00:01 of origin site. See also the dedicated section for projected stock.	Current SIT = Stock yet to reach destination at current time.	Future SIT = Stock yet to reach destination site by local time 00:01 of origin site. See also the dedicated section for projected stock.
Container Status	Total stock includes all containers in Sound and Damaged condition. Containers in state Total Loss are disregarded.	Total stock includes all containers in Sound and Damaged condition. Containers in state Total Loss are disregarded.	Total stock to a future day is calculated on demand and includes only a total number (i.e. sound/damaged split not possible).
VSA containers	Not considered in stock	Not considered in stock	Not considered in stock

ROCK Documentation : Stock