[talk-ph] Geo mystery: What is this weird northeast line running from San Juan to Montalban?

[Eugene Alvin Villar]

I was editing in Diliman yesterday when I noticed that the linear
boundary between UP Diliman and Loyola Heights and Pansol[1]
apparently went further northeast and southwest than I thought. If you
go northeast you'll notice that the southeast perimeter of Ayala
Heights[2] follows the same line. If you go further northeast, other
residential subdivisions follow the same line[3]. Go further northeast
into Rizal and there's a parallel road that follows the same angle[4],
which in Google Maps is named "Daan Tubo". So this is a pipeline?

Interestingly, the footway from Katipunan running along UP Diliman is
also called "Daan Tubo"[5]. I don't think it's a coincidence that
these two ways kilometers apart are named the same thing.

If you go the opposite direction, it seems that the barangay
boundaries between East Kamias and the Quirinos follow the same line
and ends near Cubao[6].

But, if you switch to satellite imagery, such as in Brgy. E. Rodriguez
in Google[7], you can see the same line via the house lots! You can
follow the same line all the way into San Juan where it disappears[8].

Is this a real pipeline, possibly abandoned?

I have 2 theories.

1) This is an oil pipeline. If you follow the line into Manila, it
goes close to the Pandacan oil depot. But why would it go to Rizal?

2) This is a water pipeline. The line's end in the northeast is
somewhat close to Wawa Dam and this dam used to supply Metro Manila's
water before the Angat-La Mesa dam system became operational. In
addition, the line passes right next to the MWSS reservior at San
Juan[9]. I have a hunch that this is the correct answer.

What do you guys think? :-)

Here's a overview map of this line:
http://maps.google.com/maps/ms?ie=UTF8&t=k&hl=en&msa=0&msid=213651493644683398187.0004a0688716ea01927e5&ll=14.66929,121.041527&spn=0.163409,0.312424&z=12


[1] http://osm.org/go/4zhTLvxM-?m
[2] http://osm.org/go/4zhTzuAL--?m
[3] http://osm.org/go/4zhT@d1F--?m
[4] http://osm.org/go/4zhcZBkv-?m
[5] http://osm.org/go/4zhTkJ3ti--
[6] http://osm.org/go/4zhSdpfW?m
[7] http://maps.google.com/?ie=UTF8&t=k&ll=14.626181,121.052459&spn=0.005108,0.009763&z=17
[8] http://maps.google.com/?ie=UTF8&t=k&ll=14.609478,121.034564&spn=0.005108,0.009763&z=17
[9] http://maps.google.com/?ie=UTF8&t=k&ll=14.614253,121.040915&spn=0.005108,0.009763&z=17