Daniel Mohammad Rosyid , Surabaya | Mon, 10/05/2009 1:24 PM | Opinion
Recently, probably inspired by the Suramadu bridge, a plan to build a bridge to connect Sumatra and Java was launched by the Banten and Lampung provincial governments and a civil engineering consultancy company.
The 2009 annual budget speech of the President also mentioned the plan as part of a program to develop basic infrastructures in Indonesia.
But the bridge will not solve the connection problem, but even actually create new problems.
An economic and technical analysis will show the inferiority of the bridge compared with the much cheaper, quicker to implement and more robust advanced ferry system alternative.
This short article will use a topology argument – a branch of mathematics – to demonstrate that the bridge will not improve the present connectedness of the two islands, but, on the contrary, will reduce connectedness.
To start with, there is an implicit assumption – derivable from a “big island or continental” mindset – that there are only two ways to connect two islands: building a bridge or a tunnel. This mind-set sees a strait like a huge river. Within this mind-set, connecting the islands with a bridge is similar to building a bridge across a river.
There is also another assumption: That building a bridge will automatically promote significant regional economic development.
However this is not the case, i.e. a strait is not the same as a river, and while the positive regional impact of building a bridge across a river is well documented, the rationale for building an inter-island bridge is only based on unsubstantiated claims.
Up to now, there is no known scientific evidence that an inter-island bridge or tunnel brings about significantly positive regional economic impacts to the islands so connected.
The 50-kilometers Euro tunnel that connects Dover and Calais is a well-known mega-project that has proved to be a regional economic disaster for England at least.
The topology argument goes as follows. An island is almost always a concave landmass domain in which there are always 2 set of points in the domain that cannot be connected via a straight line unless some segment of the line lies outside the domain. As a comparison, a perfect 2-dimensional circle plane is a convex domain. Any domain that is surrounded by straight lines is also a convex domain.
The presence of holes, and cuts in this convex domain makes it a concave domain. From this definition, it is obvious that concavity, i.e. the presence of rivers as cuts in the domain, creates a distance problem in the domain, and therefore a bridge is a straight-forward solution to a distance problem, or a connectedness problem, in a concave domain.
Now consider two separate concave landmass domains, i.e. islands. Building a fixed “connector” such as a bridge between the two domains will create a new, combined, and larger concave land mass domain. Since concavity creates a distance problem, the inter-island bridge does not solve it, but in fact creates a new distance problem that requires an additional bridge to solve it.
The inter-island bridge location is usually selected such that it represents the shortest distance between 2 points in the islands to cut the cost of building to the minimum.
But this proves to be problematic, i.e. there are always another 2 set of points that becomes longer to connect if one is forced to do it via the bridge.
To solve this new distance problem will require a new, additional bridge to be built. But this further increases the concavity of the combined domain. The problem therefore becomes non-linear.
To avoid this problematic non-linearity, one needs only to change one’s mind set to see that a strait is naturally different from a river, and that the water between the concave landmass domains is the natural connector of an unlimited number of points.
One then simply uses ports and ships to provide a flexible, and movable means to exploit these natural water bridges.
In other words, an artificial bridge only provides, a fixed, single-connectedness, while the natural bridge of sea water provides multiple-connectedness. Building a bridge therefore drastically reduces the connectedness between the two islands.
Shifting one’s mind-set from “the big island” to “the archipelago” mind-set thus provides a “relaxed” distance problem in which one is not obsessed with a single-mode transport solution to a distance problem.
The bridge solution is a single-mode trap that is not sustainable in terms of energy, environment, and reliability of archipelagic Indonesian transportation systems.
An advanced ferry system is not only more cost-effective, but also a more difficult target for terrorist attacks, more adaptive to fluctuations in traffic demand, and it will also promote multi-modalities.
To conclude, the Selat Sunda bridge will not solve a connectedness problem between Sumatra and Jawa, but will in fact undermine the connectedness that already exists.
Daniel Mohammad Rosyid, Ph.D is a lecturer at the department of ocean engineering, 10 November Institute of Technology (ITS), Surabaya.