Improving safety at Tesco Frozen Distribution Centres.

A revolutionary new site management system has recently been installed at the DHL-run Tesco National Frozen Distribution centre in Daventry.

The system is saving the company hundreds of man hours and dramatically improving efficiency and safety. DHL Supply Chain Ltd employed integrator Piggott and Whitfield (P&W) to develop an IP CCTV system for observing frozen pallet placement and health and safety practise in its deep freeze, automated distribution warehouse.

The Tesco National Frozen Distribution Centre is one of four similar facilities run by DHL Supply Chain Ltd for Tesco in the UK. It has 500 members of staff working 24/7. The deep freeze warehouse is made up of 12 double sided aisles for pallets. It operates at -22°C with fully automated Dematic cranes operating continuously. Aisles are 35m tall and 100m long with three intermediate floors between groups of Aisles, with conveyors where staff members pick goods for delivery to Tesco stores.

The challenge

Suppliers have scheduled delivery times for unloading their frozen cargos. The faster this is done, the better, for maintaining the deep freeze environment.

However, the Dematic cranes will not place a pallet on a shelf if they sense an obstruction, which can be anything from loose packaging to a misplaced or damaged pallet. A member of staff then has to harness up in freezing conditions and climb anywhere up to 35m above the ground to remove the obstruction themselves or guide a crane for removal. This can take 15 – 20 minutes and happens as much as 100 times a week. As well as delaying the unloading and stacking process, if the person should fall, although the safety ropes will hold them, they can experience suspension trauma. In the freezing conditions, this can mean they only survive for 15 minutes. Clearly, strict adherence to Health and Safety procedures is critical in mitigating risk.

The solution

P&W installed tough, vandal-resistant, low temperature, infra-red Grundig IP CCTV dome cameras supplied by The Security Buying Group. The cameras, which are heated, operate at extremely low temperatures, in the dark and are powered by PoE (Power over Ethernet) for minimal temperature impact. The cameras are installed on each side of the cranes looking towards the shelves in the aisles.

A VMS (video management system) processes and records camera video streams, allowing operators to view images from the cranes using wireless, tough notebooks (portable HMI screens). If a crane stops for any reason, they can identify the obstruction and in most cases override the crane to place the pallet.

“P&W was able to create a bespoke wireless network solution that kept the CCTV security data within the DHL network separate from Tesco’s own data network,” explained Billy Currie, Campus Automation and Facility Manager at DHL Supply Chain Ltd. “Other companies had tried to offer a solution, but failed.”

Chris Riesen, Intelligent Solutions Manager at Piggot and Whitfield stated, “P&W’s specialist network and data communications expertise provided a bespoke solution to a difficult challenge. We trialled a system in one aisle, before implementing the system across the warehouse. There were a lot of demanding criteria to meet including low temperatures; wireless operation because of crane movement; low light operation; and a robust network solution separated from the wider Tesco distribution network.”

The results

“We could not have predicted the effectiveness of the system,” said Billy Currie. “In 96 – 99% of cases, my staff can override the crane sensor and continue operation. Before the installation, we would have around 100 stoppages a week, so efficiency has been dramatically improved through reduced downtime!

“Site Health and Safety has also been improved as staff members rarely have to scale the shelves to check for obstructions. We have also been able to ensure staff members adhere to our strict Health and Safety whilst working at height and in deep freeze conditions, reducing risk to themselves and the business. DHL has been able to reduce risk and improve staff performance.

“An additional efficiency benefit has come from identifying and informing suppliers using pallets unsuitable to the deep freeze environment. DHL discovered that many of the genuine sensor alerts were caused by pallet debris. The company has been able to identify suppliers that offer pallets unsuitable to the freezing conditions and have improved supply chain efficiency as a result.”

Billy Currie added, “P&W has provided a system that no other integrator could offer. They have installed a live, proactive IP CCTV system in a challenging environment which works alongside crane sensors in an intelligent manner. Most significantly they have provided a wireless solution that operates solely on the DHL network without interfering with the Tesco network. No other installer we approached came anywhere near finding a practical solution to the issues we faced.”

DHL Supply Chain Ltd is now hoping to add IP CCTV to other areas of the site, to ensure Health and Safety compliance and to dramatically improving efficiency and safety. The system will also be rolled out to the other frozen distribution centres in the UK.