Benefits in civil design
The most immediate benefits of BIM
in the case of road and highway design are better designs and
increased efficiency and productivity. Because design and
construction documentation are dynamically linked, the time needed to
evaluate more alternatives, execute design changes and
produce construction documentation is reduced significantly. This is
particularly important for transportation agencies because it
can shorten the time to contract letting, resulting in projects being
completed sooner and within more predictable timetables.
Beyond efficiency and productivity,
BIM facilitates roadway optimisation by including visualisation,
simulation and analysis as part of the design process. Many
criteria can be assessed to achieve an optimal roadway design, for
example in terms of constructability, road safety and sustainability.
Constructability
Civil engineers typically design for
code compliance, not for constructability. But incorrect
interpretations about design intent made in the field because of
ambiguous documentation can lead to delayed schedules, change in
orders and RFIs (requests for information) after construction begins.
Consider a typical new highway
construction project with bridges and interchanges budgeted for $100
million. Typically, about seven to eight per cent of the
investment will go into design development. Reducing the design spend
by 35 per cent with a more productive process saves $2.6 million. But
reducing the construction portion by 15 per cent by considering
constructability during design saves nearly $14 million. These
savings don’t take into account litigation that can result from
mistakes in the field. Designing for constructability can help reduce
these mistakes before they become a problem.
Road safety
Analysis to ensure safe stopping and
passing sight distances is a key factor driving design decisions.
Traditional sight distance analysis is based on mathematical
equations applied to vertical curvature in the road profile. But this
approach fails to take into account factors such as horizontal layout
and visual obstructions. Integrating interactive visualisation and
sight distance simulation into the design process allows the civil
engineer to identify quickly whether the road geometry meets critical
safety parameters related to sight distances, including grades, curvature,
and visual obstructions such as barriers, berms and foliage.
Probably the most significant advantage
of BIM compared with a drafting-centric process is the ability to
extend the use of the information model beyond design, analysis and
simulation into construction and, eventually, operations. For
example, transportation agencies increasingly are using the 3-D model
for operating construction equipment with GPs (global
positioning system) machine guidance. Benefits include increased
productivity and accuracy, reduced survey costs, lower
equipment operating costs and an extended work day.
Sustainability
Sustainable design is gaining
momentum with civil engineers, and it is quickly shifting to standard
practice. BIM enables sustainable design for civil engineers by
allowing them to evaluate more design alternatives and integrate
analysis into the design process.
Using BIM software, civil engineers
can more easily predict the outcome of their projects before they are
built. By creating coordinated, reliable design information, civil
engineers are able to respond to changes faster; optimise designs with
analysis, simulation, and visualisation and deliver higher quality construction
documentation. Starting with surveying and all the way through to
supporting construction processes, BIM allows the extended civil
engineering team to extract valuable data from the model to facilitate
earlier decision making,more sustainable designs and faster, more economical
project delivery.This approach is essential for sustainable design, which
requires the integration, analysis and optimisation of environmental,
social and economic factors for the life of a project. With
traditional drafting-based design processes, the civil engineer often
delivers the first design that meets code – but this is not
necessarily the best design.
Storm water management
The more sustainable storm water management practices minimise
erosion, encourage natural infiltration and recharge aquifers. Employing
best management practices (BMPs) such as permeable pavements, rain
gardens, bio swales and infiltration basins is becoming
standard practice. The integration of hydraulic and hydrologic
analysis with civil engineering design models makes it much easier for
civil engineers to evaluate the environmental impacts of BMPs and
determine the most sustainable solutions. Steep slope protection:
sustainable design for steep slope protection aims to
minimise erosion, protect established habitats and reduce stress on
natural water systems by preserving the natural and vegetated
state of steep lopes. Using the geo-spatial analysis and mapping
capabilities that are integrated with a design model, engineers
can quickly query the surface data and visually display
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