After decades of decline in the mid-to-late 20th century, the economic vitality and safety of many urban cores have stabilized, making them more attractive for workers and residents. The productivity and increased potential for economic activity that comes from dense development had made households and firms willing to pay a premium for space in city centers and accessible urban neighborhoods. Modern urban renewal now emphasizes “placemaking” in which new development interacts with its environment to create communities with activity throughout the day and night.

The increased interest in living and working in cities has placed a higher demand on the built environment. The return to cities has directly increased demand for residential and office buildings, but has also increased demand for space to accommodate businesses used by urban residents and firms, as well as for the transportation and utility infrastructure necessary for a complex urban eco-system to function.

This demand for buildings and infrastructure is not without challenges. Construction in the urban environment is higher cost and higher risk than building in an undeveloped area, due to logistical constraints and existing facilities on and adjacent to the site. These challenges are compounded when dense urban development requires new facilities to be constructed below ground.

Urban sites are different because available land is scarce and expensive, affecting land use and programming of facilities. As a result, construction is often taller, deeper below ground and closer to other buildings and infrastructure. This increases the cost and complexity of construction. It also increases the consequences if things go wrong. If a large urban project is delayed due to construction adversities, the increase in construction cost, delayed revenue generation and third-party claims can add up to an astronomical loss.

A lot of design professionals like to work in a vacuum, but that is not an option when designing for an urban site. Existing structures above and below ground may encroach upon or obstruct planned new construction and present hard constraints. Common types or methods of construction like pile driving, mechanical rock excavation or flexible excavation support present hazards to adjacent structures. The new structure, construction methods and damage risk to nearby buildings and infrastructure are interrelated. Like it or not, it is not sufficient to wait for construction to begin before managing these risks; they must be considered in project design.

Urban construction is different and requires different approaches to design and construction. What works for rural or suburban projects may be cost-prohibitive or high-risk on an urban site. Proactive risk management and consideration of constructability are important for project success. This requires an integrated approach to foundations, below-grade structures and management of construction impacts to existing facilities above and below ground.

The information and statements in this document are for information purposes only and do not comprise the professional advice of the author or create a professional relationship between reader and author.