Medway Tunnel: SCADA System Replacement
The 725 metre long Medway Tunnel is an immersed tube dual two-lane tunnel with cut and cover approaches that was opened in 1996. Despite the relatively recent build, a new SCADA control system was required to replace the proprietary system had reached end of life and no longer supported giving rise to a high risk should a component failure occur.Ematics were awarded the contracted to design, supply, install, test and commission a range of new systems for the Medway Tunnel, including
- Dual Redundant SCADA.
- Dual Redundant PLC systems.
- 24Hr Remote Monitoring.
- Ethernet Data Communications Network.
- Maintenance Radio System.
The core solution is based upon new dual redundant SCADA servers and hot standby PLCs, as well as a new gigabit, fibre optic network utilising a stacked switch infrastructure capable of handling many IP based sub systems both for this project and for future enhancements.
The Medway Tunnel SCADA system consist of dual redundant SCADA servers with 5 clients workstations. The duty/standby Servers are installed in separate buildings providing geographical segregation in the event of building failure or personnel lockout. These servers are linked via a dedicated fibre link to facilitate the synchronisation efforts of each SCADA server.The SCADA system provides the following functionality in a number of operator locations:
- IP based CCTV System.
- Emergency Telephone system Upgrade to IP.
- Video Incident Detection system.
- Radio Rebroadcast System.
- Brand New Operator Control Room.
Graphical representation of all plant systems; control facilities for all operator procedures on all the workstations; facilities for archiving, retrieving and viewing previously stored data.
The Schneider Quantum CPUs were introduced as the Master PLC’s since they have a very high level of availability required by the project. These PLC’s, were configured using the Unity Pro software package and all software was designed to BS EN 61508 SIL2 as required for critical applications demanding high-availability control system architectures, where control system failures are out of the question.The Schneider Advantys STB Modular I/O system was used for connecting the field equipment to the SCADA /PLC Systems. Ethernet Network Interface Modules were used to provide a remote I/O Islands over Ethernet at each of the required locations ensuring a reliable, affordable and future proof solution that can be easily expanded using the new Ethernet infrastructure.The existing Allen Bradley SLC500 PLC system was then replaced with these Schneider Advantys STB Remote I/O over Ethernet, replacing the existing DH435 PLC network which only offered speeds of 0.5MB/Sec was replaced with an Ethernet network at 100MB/Sec.At each of the installed locations, the remote I/O Island uses a Network Interface Module, Power Distribution Modules and a various configurations of modular Digital and Analogue I/O Cards required for each island to perform its control and monitoring activities.
Each remote I/O island is expandable up to 32 modules per island making this a very flexible solution.
- Tunnel Ventilation Control and Monitoring.
- Tunnel Lighting Control and Monitoring.
- Traffic Management Control and Monitoring (VMS).
- Incident Management and Support.
- Sump Control and Monitoring.
- Emergency Telephone Monitoring.
- CCTV PTZ Control and integrated video display.
- Fire, Security and Electrical Distribution Monitoring.
- SCADA Equipment Monitoring.
- Alarm Handling / Reports.
- Remote Location Control & Monitoring via Medway WAN.
Ethernet Network Infrastructure
A new fibre backbone was designed and installed in the tunnels and buildings using the Cisco® Catalyst 3750G series Ethernet switches. These switches are multilayer with Fast Ethernet and Gigabit ports and featuring Cisco StackWise™ technology, allowing for the creation of highly resilient networks.
Stacking the switches simplifies the network topology by reducing the number of Switch IP addresses as they all become a single managed device helping to reduce the convergence time of the network.
To create a dynamic fault tolerant network in the tunnels, the Cisco IE-3000-4TC Industrial Ethernet switch was installed in the EDP cabinets, these switches provide four Ethernet 10/100 ports and two dual-purpose uplink ports which are populated with SFPs to connect back to the backbone.
By adding a number of additional fibre cores between the east and westbound tunnels, we were also able to further increase the overall resilience of the network since it can now withstand multiple breaks within the same tunnel before any loss of communications is experienced.
Network Infrastructure Features
The network infrastructure was not just designed to support all the sub system upgrades provided by this project such that a common Ethernet solution could be provided through all sub systems, but to protect the investment of the project by future proofing the tunnel and the works by providing a modern expandable and resilient network structure capable of expansion without compromising reliability or performance. Some of the features provided by the infrastructure are:
- 100% Cisco Solution
- Stackwise Technology for easy expansion
- Broadcast segmentation of subsystems with VLANs
- Virtual LAN (VLAN) support.
- Inter VLAN routing.
- Per port Unicast, Multicast & Broadcast Storm Control.
- Switching loop protection using rSTP and MST (Rapid Spanning Tree).
- No single point of failure.
- Independent Network Management System.
The CCTV system includes 16 Bosch PTZ cameras in the tunnels and approach roads providing 100% coverage and a number of Axis PTZ cameras providing coverage in the tunnel buildings and compound areas all of which are fully integrated in to the SCADA allow the operator to video view and PTZ control directly from the SCADA workstation.
To support the CCTV system, Vital has provided a new video wall system in the tunnel control room and two new video wall systems at a remote monitoring and control facility. The two system integrate Medway’s existing surveillance cameras with the new tunnel CCTV cameras in to a single medial wall solution. The new media wall replaced their old CRT monitors with new LED flat screen monitors and replaced an existing Dedicated Micros pick-a-point video wall with a modernised version for processing their existing legacy video streams. The solution was custom designed for Medway and typical features of the architecture is illustrated in the diagram below:
For the operator control room, Vital designed and installed a new control room by remodelling their old canteen room. The new control room was fully fitted included suspended ceiling with lighting systems, air conditioning, desking and assorted plants and accessories to create a modern and comfortable environment for the operators.A new video wall comprising of 2 x 52” LED monitors was installed using “DiGiWall” Software complimented with “DigiArchive” video recording system and the DigiLive CCTV client software. The Video Wall provides the operators with an video from all cameras whilst allowing operators to send information to the wall directly from the SCADA workstation.DigiArchive is an “all-in-one” storage and retrieval solution for managed monitoring. It is designed for mission-critical applications that require instant access to digital content 24/7.
Developed by our sister company Sicura Systems, DigiArchive, DigiWall and DigiLive provides state of the art storage and retrieval solution designed for mission-critical applications that require instant access to digital content 24/7.For Medway, DigiArchive stores all video footage for a 30 day period and allows precise, speedy retrieval when an incident requires review. On playback, video footage is shown to the operator in relevant time, date and categorised order so that events can be evaluated, and a recording given to third parties such as police and judicial authorities.
Incident Detection System
In order to support the Automatic Incident Detection system, an additional 32 cameras were installed in the tunnels. These cameras are dedicated to the provision of incident detection system, which for the Medway Tunnel can recognise the following incidents:
To reliably provide these detections, the Bosch NWC0495 IP Camera was selected as it meets the technical requirements needed for incident detection in tunnel environment and were installed every 50M, with additional cameras located at the east tunnel which is significantly wider at the exit portal.
- Pedestrians in the tunnel.
- Stopped Vehicles.
- Fallen Objects.
- Vehicles travelling in the wrong direction.
Emergency Telephone Upgrade
The existing Tunnel Emergency telephones are located in each of the EP’s down in the tunnel bores. The telephones are older type analogue phones and use the normal POTS signalling with 50V on the line when on hook. These have now been migrated to the Medway WAN and incorporated on to their Cisco Unified CallManager system.
IA Cisco ISR3845 and two high density FXS cards is used to connect the tunnel handsets. Calls from these handsets are routed back via the IP network, first to a handset in the WSB, then on busy or no answer to the MCCC handsets using H323 for audio and the Skinny signalling Control protocol (SCCP).Vital have developed a custom TAPI interface for the SCADA system to fully integrate these emergency telephones in to the new SCADA system in order to make the best use of the existing systems currently being used by Medway bringing about a cost saving by converting a legacy system to a modern IP based solution.
Network Management System
A Network Management System (NMS) called Whatsup Gold was installed and configured for all switches to trigger alerts based on switch and port status including CPU usage, high bandwidth, switch uptimes and many more features that are required to provide a fully functional network management system.
The NMS is installed on a dedicated Dell PowerEdge server setup such that it can be accessed via any PC on the network via internet explorer to provide feature such as:
- Predictive and pre-emptive monitoring of networks and systems infrastructure and core IP services.
- Automated network discovery and mapping.
- Alert management platform, featuring easy to use alarms, alerts and notification capabilities for real-time operations support
- Quick navigation via Web and Windows consoles.
- High security and configurable role-based management.