WSP is leading the way in the application of Grade of Automation 4 (GoA4) on landmark metro projects across the globe. From Sydney to Bogota, Amsterdam to Copenhagen, Doha to Riyadh and beyond, WSP has been at the forefront of ensuring metro systems take advantage of automation technology. 

What is GoA4?

GoA4 is the highest level of automation – the process by which responsibility for operating the train is transferred from the driver to the train control system. GoA4 metros, such as Sydney metro and Paris lines 1 and 14, operate fully unattended i.e. without a driver on board. GoA4 operation relies on three systems working together: 

• Automatic Train Protection (ATP): responsible for safety
• Automatic Train Operation (ATO): responsible for driving the train automatically
• Automatic Train Control (ATC): responsible for route setting and train regulation, ensuring the train runs on time

At GoA4, the ATP, ATO and ATC functions utilise on-board and wayside equipment to exchange data and perform functions undertaken by humans in a GoA1-3 systems. The system takes over responsibility for: ensuring safe movement (safe route, safe separation, safe speed), driving (acceleration and braking), passenger transfer (door operation, safe starting conditions), supervising guideway (prevent collisions with obstacles and people), and detecting emergency situations (perform diagnostics, detect fire, derailment, handle emergency situations). 

How can automation optimise metro systems? 

GoA4 reduces response times and variabilities that come from human control, which optimises the running time of trains by increasing the average speed and reducing dwell time in stations. This enhances reliability, shortens waiting times for passengers and reduces operational costs. Train regulation systems can also optimise energy use and reduce maintenance costs through smoother driving standards and optimal acceleration and braking profiles.

Upgrading existing railway lines

The process of upgrading an existing railway line from manual to fully automatic operation has been proven to be significantly more challenging than opening and operating a “greenfield” metro line. Reasons for this are numerous, from inherent design issues such as tunnel size restricting operational solutions to existing organisational processes proving difficult to change for reasons including safety, employee relations and enabling continuity of service during migration.

Any change from manual driving to automatic operation presents numerous safety, technical and operational challenges. These are not just related to the complexity of the upgraded signal and control systems being introduced, but also to the process of adapting the Railway Line infrastructure and the Railway Operations and Infrastructure Maintenance Organisation to deal with the wider implications of fully automatic train operation. 

Some examples of the implications are : - 

• Changing processes to manage degraded modes and failure modes that are exacerbated by the absence of a member of staff either permanently in the driving position on the train or even on the train at all.
• Increased monitoring and control responsibility in the central control room for activities that would have previously been performed by the driver. 
• Integrating new trackside infrastructure (e.g. platform screen doors, intrusion detection systems, access control systems, remote supervision systems) to mitigate any hazards introduced by the change from manual driving to automatic operation.
• Managing additional hazards associated with driverless operation that have an impact on staff and passenger safety (both on platforms and on the trains themselves) and adapting existing training arrangements with new competencies for operations and maintenance staff.
• Managing additional hazards that arise from staff accessing the track for planned and unplanned maintenance and changing the additional rules and instructions that apply under non-automated railways.
• Ensuring customers continue to receive the service they need. The disbenefits of disruption during transition can easily outweigh the longer term benefits if not managed properly.

How can WSP help?

WSP has extensive experience of delivering GoA4 system development, system-wide integration and technical advisory on metro projects around the globe. We played a significant role in delivering Doha’s first fully automated passenger railway and have been instrumental in developing Riyadh’s state-of-the-art fully automated transit network. 

As well as developing new, automated metro lines, WSP’s railway engineering and operational specialists have significant experience of converting existing “brownfield” metro and heavy rail lines operating at GoA1 (automatic train protection with manual driving) to GoA2-4 operation. For example, on Sydney Metro Northwest we developed the migration plan to convert the existing line into a metro line with minimal disruption to the existing Sydney Trains operations. For the Sydney Metro City & Southwest section, we adopted a similar strategy to covert the existing GoA1 line to GoA4 whilst taking additional measures to ensure segregation with an adjacent dedicated freight railway. We also designed the replacement of the train control and power supply distribution systems on the Taipei Metro Neihu Line.