Simplicity, modularity, and speed in mega project construction

Alon Levy at Pedestrian Observations argues that Southern Europe (Italy, Spain, and Turkey in particular), South Korea, and Switzerland, followed by Nordic countries are the lowest-cost places for subways construction. 

On the reasons for this lower cost construction, he writes,

Like Italy, Spain has not undergone the creeping privatization of state planning so typical in the UK and, through British soft power, other parts of Northern Europe. Design is done by in-house engineers; there’s extensive public-sector innovation, rather than an attempt to activate private-sector innovation in construction. Southern European planning isn’t just cheap, but also good. Metro Milano says that M5 carries 176,000 passengers per day, for a cost of 1.35b€ across both phases; in today’s money it’s around $13,000 per rider, which is fairly low and within the Nordic range. Italian driverless metros push the envelope on throughput measured in peak trains per hour, and should be considered at the frontier of the technology alongside Paris. Milan, Barcelona, and Madrid have all been fairly good at installing barrier-free access to stations, roughly on a par with Berlin; Madrid is planning to go 100% accessible by 2028... Italian corruption levels in infrastructure are very low, and from a greater distance this also appears true of Spain.

The point about the superior public sector planning, design and innovation in infrastructure projects is interesting and goes against the conventional wisdom which almost reflexively attributes these only to the private sector.  

The blogpost also links to this post by Bent Flyvbjerg who finds speed and modularity as the two reasons for Madrid's metro success. Madrid Metro completed 76 stations covering 131 km in two four year phases from 1995 using radically innovative approaches to tunnelling and station building. 

The Madrid Metro leadership decided that no signature architecture would be used in the stations, although such embellishment is common, sometimes with each station built as a separate monument... Signature architecture is notorious for delays and cost overruns... Their stations would each follow the same modular design and use proven cut-and-cover construction methods, allowing replication and learning from station to station as the metro expanded. 

The project would eschew new construction techniques, designs, and train cars. Again, this mindset goes against the grain of most subway planners, who often pride themselves on delivering the latest in signaling systems, driverless trains, and so on... They cared only for what worked and could be done fast, cheaply, safely, and at a high level of quality. They took existing, tried-and-tested products and processes and combined them in new ways... 

Traditionally, cities building a metro would bring in one or two tunnel-boring machines to do the job. The Madrid leaders instead calculated the optimal length of tunnel that one boring machine and team could deliver — typically three to six kilometers in 200 to 400 days — divided the total length of tunnel they needed by that amount, and then hired the number of machines and teams required to meet the schedule. At times, they employed up to six machines at once, completely unheard of when they first did it. Their module unit was the optimal length of tunnel for one boring machine, and like the station modules, the tunnel modules were replicated over and over, facilitating positive learning. As an unforeseen benefit, the tunnel-boring teams began to compete with one another, accelerating the pace further... And by having many machines and teams operating at the same time, the Madrid Metro leadership could also systematically study which performed best and hire them the next time around. More positive learning.

There are three distinct features. One, keep it simple and avoid new things when existing techniques and technologies are just as good. Two, as far as possible modularise construction. Three, iterate while constructing and have feedback loops to integrate learning into the construction process. The combined result is low-cost and high-speed construction of world-class metro railway systems. 

Flyvbjerg has a simple advise for construction of Megaprojects,

I’ve found that two factors play a critical role in determining whether an organization will meet with success or failure: replicable modularity in design and speed in iteration. If a project can be delivered fast and in a modular manner, enabling experimentation and learning along the way, it is likely to succeed. If it is undertaken on a massive scale with one-off, highly integrated components, it is likely to be troubled or fail.

See also this and this papers by Flyvbjerg on modularity and speed.