Design and preparation for smooth baggage handling operations

Changi Airport’s latest passenger handling facility, Terminal 3, opened in January 2008. Designed with spectacular architecture, lush natural light-filled ambience and superb effici­ency, this ultra modern facility has an annual handling capacity of 22 million passengers, boosting the total handling capacity of Changi Airport to 70 million passengers per year. Currently, six airlines operate from Terminal 3, including the national carrier, Singapore Airlines which operates from both Terminal 2 and Terminal 3.

Baggage sorting system

Terminal 3’s fully-automated Baggage Hand­ling System (BHS) connects 132 check-in counters and 14 make-up carousels via two fully-redundant tilt-tray sorters, each about 1 km long. The tilt tray sorters allow for common check-in. That means that passengers can check-in at any one of the 132 check-in counters in the departure hall and their bags will be sorted, based on baggage tag bar code readers, to the make-up carousel designated for the departing flight. In-line Hold Baggage Screening X-ray machines are integrated with the BHS to ensure that all bags are security-cleared to meet internationally recognised protocols.

Transfer baggage handling system

As part of the Terminal 3 BHS development, a 13 km long Transfer Baggage System has been installed to connect Terminal 3 with Terminals 1 and 2. This system is based on intelligent baggage trays (totes), each embedded with RFID tags to sort and transport transfer baggage between terminals automatically. Each item of baggage is placed in a dedicated tote where the bar-coded IATA license plate on the baggage tag is matched with the tote’s RFID number. The tote system also offers the potential for significant energy savings. Its modular design is comprised of a series of short con­veyors, that are only set in motion when prompted by the arrival of a tote, stopping again once the tote has moved on to the next module. Each tote is manufactured using durable but light-weight material and weighs less than 20 kg, thus further reducing energy consumption.

The tote system is installed underground and operates at a maximum speed of seven metres per second, thereby ensuring that bags can be sorted and transported from one aircraft to another within the minimum conn­ecting time of 60 minutes, whether the con­n­ecting flight is within the same terminal or in Terminal 1 or 2. Two bi-directional loops of high-speed tote conveyors back up one another to ensure reliable transport of transfer bags across terminals. At the Terminal 3 end of the Transfer Baggage System, the system is designed to discharge bags on totes directly onto the designated make-up carousels, bypass the Terminal 3 BHS sorters and thus save precious time for fast and reliable bag delivery. The deepest section of the Transfer Baggage System tunnel is built 24 metres below ground and runs below the airport train station, while the rest of the tunnels are positioned between five and eight metres below road level. Provisions are also made in the system design for bags to be checked-in and inducted from the airport train station into the Transfer Baggage System.

Early bag storage

The tote system is also used to store early bags at Terminal 3. Bags that are scheduled to leave on much later flights are conveyed automatically into an early bag storage area, which spans over two basement levels, measuring some 3,100 square metres. A computer server keeps track of the storage location and departure time of the bag and will automatically retrieve the bag and convey it to the assigned make-up carousel at the appropriate time. The early baggage storage in Terminal 3 can store up to 3,640 early bags.

BHS Control Centre

The BHS Control Centre is manned 24/7 by the system main­tenance staff. The duty personnel monitor the status and health of the BHS through a Supervisory Control and Data Acquisition (SCADA) system. The SCADA system is linked to a network of CCTV cameras for surveillance of critical parts of the system and those prone to mishandling bags. An alarm reported by the SCADA system will automatically trigger the CCTV system to bring up the video feed of the affected area. All CCTV footage is recorded to provide event trace for system improvement.

Robust system design

The BHS is one of the most important mission-critical systems at any hub airport. The Terminal 3 BHS has been carefully designed to give special attention to the need for reliability and redundancy. The system is engineered in such a way that baggage can be diverted to an alternative route should there be a component failure on a conveyor or a sub-system. In a “worst case scenario” whereby baggage has to be manually removed from a stalled conveyor, which is installed at an elevated height, an extensive network of maintenance walkways facilitates quick access to the affected baggage. In addition, recovery chutes, placed at regular intervals along the walkway, speed up the otherwise laborious process of carrying these bags down from the conveyors.

In the Transfer Baggage System tunnels linking Terminals 1, 2 and 3, “fallback recovery” conveyors and lifters are installed, to provide the operations staff with an efficient means to bring bags stalled on totes to the ground level expeditiously, should the mechanised tote conveyance system fail. The conveyors and lifters are designed in such a way that they can be powered from the mains supply or via a stand-alone mobile generator.

The computer servers of the BHS are the “brain” of the system and requirements for redundancy cannot be over-emphasised. All BHS computer servers are “hot”, backed up by an identical one which is housed in a physically separate server room. The backup server constantly scans the status of the operational server and will take over its operations should the operational server fail. Having the two gas-protected server rooms apart also ensures that baggage handling operations will not be affected in the unlikely event of a fire.

Simulation as a tool for design verification

Computer simulation was used extensively to verify the BHS design before it was constructed. Passenger traffic for the design year was simulated to confirm that the BHS sub-systems are sized adequately to the required throughput. Sensitivity analysis was used to gauge the impact of assumptions, such as transfer ratio and baggage tag read rate. Different operational scenarios, including manual encoding station manning schedule and make-up carousel opening time, are also simulated to determine the most cost-effective way to deploy ground handlers.

Operational readiness

A 90 day trial was conducted so that any flaws could be identified and resolved before Terminal 3 welcomed its first passengers. The first stage of the trial involved volunteers and airport staff checking-in, tagging their bags and sending them into the BHS. Standard Operating Procedures for bags that failed security screening and needed reconciliation with passengers were also tested in these trials. The second stage of trials were conducted with passenger chartered flights. For the last stage of the trials, Changi Airport Group worked with Singapore Airlines to select some “live” flights to arrive and depart from the new terminal. These trials enabled the airport and the airline to test the baggage handling procedures developed for operations across two terminals (Terminals 2 and 3). The trial was concluded with an “endurance test” of the BHS, where 800 personnel were tasked to check-in 10,000 bags over an eight hour period. More than 1,000,000 test bags passed through the Terminal 3 BHS over the trial period before it was opened for operations.

Business continuity planning

Even with a robust system design and after conducting comprehensive trials, it is still prudent to have in place contingency plans to manually sort baggage during system failure. The simulation model that was developed during the design stage also involved modelling various failure scenarios such as mechanical stoppages and software errors so that different contingency plans could be developed to deal with each event effectively. Exercises and rehearsals using dummy bags were also carried out so that ground handlers, security personnel and contractors were familiar with contingency plans and use of recovery equipment.

Plans for improvement

As a dynamic air-hub, Changi Airport is always seeking ways to improve its BHS. Regular communication sessions with stakeholders, such as terminal operations staff, airlines, ground handlers, system maintenance and operations personnel, serve to review key performance indicators of the system and to continuously improve operational and cost efficiency of the BHS. Improvement plans that are in the pipeline include a software test platform, and more robust power supply systems to back up its BHS operations. Changes and updates are inevitable to any system that relies heavily on Information Technology. The test platform will be a replica of the BHS servers, and software changes or updates will be tested thoroughly in an emulated environment before deploying onto the live system. This will reduce the risk of unknowingly introducing “bugs” during software changes or updates. Furthermore, the test platform will also be used as a training tool for new staff. In terms of power supply, the power source for mechanical and electrical services for the baggage handling area will be separated from the power source supplying electricity to the baggage handling equipment. This ensures that any electrical faults in non-essential services, such as lights and ventilation fans, will not affect the BHS.

Experience from Changi Airport

By drawing on the experience of operating the BHS at Changi Airport Terminals 1 and 2 and with the drive towards delivering excellence in BHS performance for Terminal 3, Changi Airport’s BHS team, together with the consul­tant, contractor, ground handlers and airlines, have partnered successfully to operationalise the Terminal 3 BHS and inter-terminal Transfer Baggage System. This ensures that passengers can always look forward to reliable baggage handling and a worry-free and enjoyable travelling experience at Changi Airport.