The key objective of the observational method is to save time or
cost while maintaining an acceptable level of safety. It provides a
robust and adaptable system for managing risk in sub-surface
construction. Since 1990 Mott MacDonald has led the application of
the observational method, achieving success in a broad range of
major projects. We've developed considerable expertise in risk
assessment, planning supervision, instrumentation, monitoring and
numerical analysis. In particular, we have developed the
application of the method through the technique of 'progressive
modification', which has overcome contractual, environmental and
technical constraints to deliver substantial savings.
Heathrow Express - construction of cofferdam in
disturbed ground conditionsThe strong compatibility
between the observational method and value engineering was
demonstrated on the Limehouse Link cut and cover tunnel, the
Heathrow Express cofferdam and the Boston Central Artery jacked
tunnels. All techniques are directed at generating savings in cost
or time. They also require an enhanced relation of design to
construction and accordingly operate well under similar contractual
conditions. The inclusion of a value engineering clause in a
construction contract can address the immediate contractual
constraints on the implementation of the observational
method.
The observational method also offers the benefits of:
- stronger connection between design and construction
- increased safety during construction
- improved understanding of soil-structure interaction
- improvements in the use and performance of instrumentation
- high-quality case history data
- greater motivation and harmony in the project team
Boston Central ArteryKey projects
which have have used the observational method include:
- Channel Tunnel, UK
- Medway Tunnel, UK
- Jubilee Line Extension - Contract 102
- Heathrow Express, UK
- Boston Central Artery, USA
