A skyscraper deadline was too tight to finish the design, then demolish the old building, then build — so the contractors stopped waiting for each phase to end and ran all three at once.

the problem

a project's standard sequence of dependent phases makes the total timeline impossible to hit, but each phase seems to genuinely require the one before it to finish first

background

what everyone would do

The conventional construction sequence was to finalize the full architectural design, demolish the existing building on the site, and only then begin building, treating each phase as genuinely requiring the prior phase's complete finish before the next could start.

what they saw

Starrett Brothers and Eken saw that the strict sequential order wasn't dictated by physical necessity everywhere, it was dictated by convention, and while some dependencies were genuinely real, foundation work in a specific location did need demolition finished there first, the phases as a whole weren't one single unbreakable chain, they were a set of workstreams whose actual physical and design dependencies only applied locally, not globally. Rather than accepting the whole project as strictly sequential because parts of it were, the fix was mapping out where design, demolition and construction could genuinely run in parallel across different parts of the site and building, and running those workstreams concurrently wherever the real dependencies allowed it.

the move

Construction began on portions of the site while demolition and excavation were still underway on other portions, and steel erection on the lower floors started before final specifications for the upper floors had been completed — foundation work began March 17, 1930, the first structural steel went up April 7, and by June 20 steel had already risen to the 26th floor, all while design and site-clearing work for later stages continued in parallel elsewhere on the project.

why it works

Beginning construction on portions of the site while demolition and excavation continued elsewhere, and starting steel erection on lower floors before final upper-floor specifications were locked, meant work never sat idle waiting for an entire phase to finish everywhere before the next phase could begin anywhere, compressing the total timeline by exploiting exactly the local, not global, nature of the real dependencies. Because the overlap was mapped out in detailed, coordinated schedules rather than left to chance, each workstream could proceed without colliding with or being blocked by unrelated work happening elsewhere on the project, which is why the building topped out at 1,048 feet just 23 weeks after construction began, with peak weeks placing roughly 22 stories of steel in 22 working days, a pace strictly sequential phasing could never have achieved. This deliberate parallelization of phases assumed to be strictly sequential is why the project's schedule became the foundational case study for fast-tracking, now standard practice across major infrastructure projects whenever deadlines make the conventional sequence impossible.

the payoff

The building topped out at 1,048 feet by September 19, 1930 — just 23 weeks after construction began — finishing significantly ahead of an already extraordinarily aggressive schedule, with peak steel-erection weeks placing roughly 22 stories of steel in 22 working days, a pace conventional sequential scheduling would not have made possible.

where it breaks

The mechanism depends on the phases' dependencies genuinely being local and separable rather than truly global, some tasks really do require full completion of a prior phase everywhere before the next can start anywhere, and forcing overlap onto a genuinely indivisible dependency risks rework, safety hazards, or structural failure rather than time savings. It also depends on having the coordination capacity to map and manage the overlap in real detail, running parallel workstreams without careful scheduling and communication between them risks exactly the collisions and conflicts strict sequencing was designed to prevent in the first place, meaning the technique trades scheduling simplicity for a real, ongoing coordination burden. And overlapping phases before earlier ones fully lock in their specifications, starting steel erection before upper-floor design was finalized, means later design changes can be more costly or disruptive to accommodate than they would have been under a fully sequential process, a real risk this approach accepts in exchange for speed.

what came after

The Empire State Building's overlapping-phase construction schedule remains a foundational case study in construction management and project scheduling for deliberately parallelizing phases assumed to be strictly sequential, and the same underlying technique — fast-tracking, where design, procurement and construction run concurrently rather than in a strict waterfall — is now standard practice across major infrastructure and skyscraper projects worldwide when deadlines make the conventional sequence impossible.

references

1. [1]How the Empire State Building's Construction Remains a WonderBuilt by Bluebeam, 2021blog.bluebeam.com
2. [2]The 'Race Into the Sky' That Built the Empire State BuildingEngineering News-Record, 2021enr.com

keep it

same kind of clever

• 1911 · Aalsmeer Flower Auction (Royal FloraHolland)Aalsmeer sells its dying flowers by racing a price downward instead of bidding one upward
• 1911 · Roald Amundsen's South Pole expeditionAmundsen marked his supply depots sideways to the route, not along it, so a lost party could still walk into one
• 1841 · P.T. Barnum (American Museum)Barnum cleared his overcrowded museum by making the exit look like an exhibit