In an automated truck loading terminal, the goal is for every step from the driver's arrival at the gate to the issue of the delivery document to run on verified data, with as little manual entry as possible. Automation is not a single device or software package. It is a layered structure that runs from field instruments through batch controllers and the safety layer up to the terminal automation system (TAS) and the enterprise resource planning (ERP) system. How far each layer is automated depends on terminal throughput, commercial processes and the systems already in place.
Automation layers
Layer | Role | Typical components and functions |
Field | Measurement, flow control and sensing of physical permissives | Meters, temperature and density measurement, control and shutoff valves, arm position switches, ground and overfill sensors |
Batch controller | Delivering the preset quantity correctly | Loading profile, temperature and density correction, additive and blending control, transaction record |
PLC and safety layer | Collecting permissives and maintaining a safe state | Pump and valve interlocks, emergency shutdown (ESD), alarm handling |
Terminal automation system (TAS) | Running the loading process according to business rules | Driver and vehicle identification, order matching, bay allocation, load records, reporting, inventory reconciliation |
ERP | Commercial and accounting processes | Customer orders, invoicing, stock accounting |
The boundary between layers varies by project. In some terminals the batch controllers talk directly to the TAS; in others permissives and pump control run through a PLC. What matters is defining up front where each piece of information is created, which system holds the master record, and what happens when communication is lost.
Levels of automation
· Local control: the operator enters the quantity at the batch controller, permissives are gathered at the bay, and records come from the controller or are kept by hand.
· Bay automation: controllers and permissives are tied to a PLC and SCADA system; pump and valve control is centralized, but order and driver matching is still manual.
· Terminal automation: the TAS receives order data, identifies the driver and vehicle, allocates a bay, downloads the load to the controller and returns the results to ERP.
Moving between levels can be done in stages. The cost of each step is usually driven less by software than by the communication capability of existing controllers, field cabling and the condition of permissive hardware at the bays.
From gate entry to delivery document
1. The driver and truck are identified at the gate with a card or similar credential; the system checks driver authorization and vehicle registration data.
2. The order or load instruction for that truck is matched, fixing product, quantity and compartment split.
3. The truck is directed to a suitable bay.
4. At the bay the driver is verified again and the load data is downloaded to the batch controller.
5. Loading starts once ground, overfill and arm position permissives are present, and stops if any of them is lost.
6. Delivered quantity, measurement conditions and events are recorded for each compartment.
7. A delivery document is produced at exit and the transaction is passed to ERP.
When a transaction becomes commercially final is set by contract and regulation. OIML R 117-1 notes that measuring systems, especially for loading road tankers, may be designed so that the transaction is not settled when the customer leaves the site, subject to prior agreement with the supplier. In that case, the document, record and correction workflow needs to be defined explicitly in the system.
Permissives and safety logic
In an automated terminal, a loading permissive means several conditions are met at once: truck ground, a healthy overfill circuit, an arm connected to the correct adaptor and out of its parked position, vapor hookup where required, a healthy emergency shutdown chain, and a valid load instruction from the TAS. Terminal automation software can be integrated with batch controllers so that loading halts automatically when any permissive input is lost, and some rack monitors add a vehicle identification permissive to overfill and ground checks.
Which functions belong in process control and which in an independent safety instrumented system (SIS) is decided through risk assessment. IEC 61511 sets requirements for the specification, design, installation and operation of safety instrumented systems in the process industry. A basic design principle is that safety functions must not depend on the business software that generates orders and documents.
Records, reporting and inventory reconciliation
The data captured for each load, including gross and corrected quantity, temperature, density, meter and arm identity, start and end time, and alarms, underpins both the commercial document and inventory tracking. Across the terminal, dynamic measurement at the bays is compared with static level measurement in the tanks to reconcile stock. EI HM 32 gives guidance on controlling apparent losses from measurement and accounting errors and physical losses at distribution terminals, on stock control, and on settling measurement disputes. Where loads are the basis for custody transfer, parameter changes and events must also be retained as an audit trail; this is covered in detail on the custody transfer skids page.
Integration decisions to settle early
· Which system holds master data such as customers, products and orders
· Whether bays can keep running in a local mode if communication is lost, and how records are synchronized afterwards
· Which interfaces connect existing batch controllers and PLCs
· User roles and who may change parameters and recipes
· The boundary between the operational technology (OT) network and the corporate network, and rules for remote access
TLY Enerji's contribution
Depending on project scope, TLY Enerji supports automation and control for truck loading operations: selection and supply of field instruments, PLC and SCADA based monitoring and control, PLC and DCS configuration, data collection and reporting, and testing and commissioning. Which party supplies the terminal automation software and ERP integration is agreed through the project interface list.
What we ask for in an initial review
· Current automation level and the batch controllers, PLCs and software in use
· Daily number of loads and the number of bays and arms
· Method used or planned for driver and vehicle identification
· The system that supplies order data and the expected data exchange
· Documents and reports required: delivery document, shift report, inventory report
· Whether loads are the basis for custody transfer and which metrology requirements apply
· Any risk assessment or targets already defined for safety functions
Related pages
· Multi-bay truck loading terminals: Planning the bay and arm arrangement that automation will manage.
· Custody transfer truck loading skids: Billing-grade measurement, proving and audit trail.
· Bottom loading systems: Permissives from ground, overfill and vapor interfaces.
· Fuel terminal automation systems (TAS): Automation requirements specific to fuel commercial processes.
Frequently asked questions
What is the difference between a terminal automation system (TAS) and SCADA?
SCADA mainly monitors process data and supervises equipment: pump status, valve positions, pressures and alarms. A TAS runs the loading process according to business rules: driver and vehicle identification, order matching, bay allocation, load records, documents and inventory reconciliation. A terminal can have both, and the data exchange and responsibility boundary between them should be defined at the design stage.
If the automation system goes down, does loading stop completely?
That depends on a design decision. In some terminals the batch controllers continue in a limited local mode when communication with the upper system is lost, and records are transferred once the link returns. Safety permissives must remain independent of the upper system. Which operations are allowed in local mode, and how those loads are documented, is defined in the operating procedure.
Can an existing terminal be automated in stages?
Yes, in most terminals automation advances in steps. Bay permissive hardware and controller communication are usually addressed first, followed by central monitoring, with driver identification and order integration added last. At each stage the communication capability of existing controllers and field cabling are assessed, and some older devices may need replacement.
Should safety interlocks live in the terminal automation software?
Safety-critical interlocks belong in layers that are not affected by a business software failure: rack monitors in the field, the batch controller, the PLC, or an independent safety instrumented system where required. The TAS can display and record the status of these permissives, but it should not be the sole basis for safety. Which function sits in which layer is decided through risk assessment.