As well as designing and supervising construction of tunnels
for the Piccadilly Line and Heathrow Express rail extensions, Mott
MacDonald managed rail systems integration and provided assurance
of quality completion to stakeholders London Underground, Heathrow
Express Operating Company, BAA and Network Rail before handover for
operation.
Our tunnel design role included design of forced ventilation and
smoke extraction systems. Back of house spaces for forced
ventilation are enormous, required to re-vent smoke entering the
passenger concourse and emergency evacuation routes in the event of
a train fire. The ventilation and extraction systems include high
capacity mechanical air handling plant.
Design of track, traction power systems, signalling and
communication were carried out by other parties. Both railways use
a track slab system: rail and sleepers were made up into 100m
lengths and brought in as complete modules. Power, signalling and
communications technologies for the Heathrow Express and Piccadilly
Lines are different requiring application of separate approvals,
systems and technical skills.
Heathrow Express
The Heathrow Express is owned by BAA and operated by a BAA
subsidiary, Heathrow Express Operating Company (HexOpCo), and
designed to Network Rail’s specification. The link from London
Paddington Station to Heathrow Terminals 1, 2, 3 and 4 was
completed in 1998, and the extension employed the same
technologies, smoothly meshing the new with existing systems.
Piccadilly Line
Contractually, construction of the Piccadilly Line extension was
unusual. BAA built the extension for London Underground, which owns
it, and was effectively a PPP contractor for the project. BAA
funded the cost of construction and is being repaid through a share
of ticket sale takings for journeys to and from Heathrow.
London Underground set technical and performance briefs for the
project. It demanded a capacity of 19 trains per hour and that the
tunnel diameter be larger than normal on the tube to allow for
easier emergency access and egress alongside trains.
One of the key technical challenges was meshing the extension’s new
signalling with the existing 1960s system. Though sharing the same
technology, the modern version was designed to provide enhanced
performance and robustness.
Our role
Mott MacDonald was responsible for integrating all rail and tunnel
systems, including signalling, communications and electrical and
mechanical equipment. Our role involved ensuring that each
sub-system’s functionality, interfaces and performance were well
defined and delivered as required, and that they were properly
integrated into the existing railways, delivering seamless
operation.
Integration of the systems crossed contract boundaries and included
T5 first-tier suppliers Balfour Beatty Rail Projects, Balfour
Kilpatrick and Westinghouse, London Underground’s PPP/PFI companies
Tube Lines, Connect and EdF Powerlink, and Network Rail and their
suppliers.
To achieve full integration we led key areas of work on the
projects:
- system architecture and interface definition
- requirements definition and management
- configuration and change management
- electromagnetic compatibility compliance
- development of system-wide strategies for earthing and
bonding.
Mott MacDonald also carried out reliability, availability, and
maintainability modelling and human factors analysis to ensure that
the complete rail systems would be robust, provide good service and
be user friendly.
Our role included production of the system test and commissioning
strategy that formed the basis of detailed testing and
commissioning procedures. We also produced the system safety plan
for the rail projects, complying with international rail safety
standards and in accordance with Network Rail’s ‘Yellow Book’
process for hazard identification and risk assessment. Once system
and operational hazards had been identified they were logged and
managed or reduced by defining system safety requirements.
The system developed to ensure safe delivery of the rail systems
helped in providing the necessary competence and completion
assurances for London Underground, Network Rail, BAA and HexOpCo.
Mott MacDonald teams responsible for tunnels, substructures, rail
systems, rail station and testing and commissioning were accredited
by London Underground to provide assurance. Work packages were
assessed against a defined set of assurance requirements, with
progressive assurance provided through an audit programme and a
suite of reports.
