Using a risk-based, decision-making approach to establish the right project configuration within complex urban subsurface conditions
By 2050, it is anticipated that as much as 87% of the population in the United States will live in cities. This will require transportation agencies to closely monitor how this will affect existing transportation networks and ways to minimize construction impacts. One way to address this will be a broader use of bored tunnels through dense urban areas.
Focus on innovations and risk-based decisions
Tunneling is becoming safer under difficult geological and hydrological conditions due to advancements of tunnel boring machine control systems and tunnel permanent support systems (liners) as well as materials and special details those entail. Safety aspects have risen sharply and most construction companies today require a “zero accident” policy; innovations and developments in tunneling technology largely support this trend.
Accelerated utilization of design-build procurements requires engineers to think creatively in close coordination with contractors, while paying more attention to constructability aspects and builders’ preferred means and methods. In this process, the increased emphasis is placed on risk management and making sure that parties in best position to handle risks are being assigned those. Risk management and risks-based, decision-making help significantly control the project scope, cost and schedule.
In the coming years, tunneling technology and processes, including tunnel boring machine control systems, materials and quality control are likely to advance further, allowing for better performances and an increase in the design service life of tunnels and underground structures. Additionally, the next generation of autonomous vehicles with magnetic levitation or similar systems will increase requirements for tunnels due to right of way restrictions in urban areas that will only be met by an underground trajectory that minimizes impacts on passengers.
[pullquote]This article was written by Sanja Zlatanic, P.E., Senior Vice President and Chair of HNTB’s National Tunnel Practice.[/pullquote]