MikeLigalig.com

By Jes Tirol
Columnist, Bohol Chronicle

Proem

Last June 2008 the Philippine Institute of Civil Engineers (PICE) granted me certificates of specialization in Structural Engineering. Among the almost one hundred thousand registered civil engineers in the Philippines I am specialist No. 110 in Structural Engineering and No. 19 in Geotechnical Engineering. This specialist recognition is similar to "Diplomate" recognition among physicians.

Geotechnical engineering deals with soils, rocks, and foundation of roads, bridges, structures and buildings. Therefore I have the proper expertise to comment about the flooded portion of CPG North Avenue because it is within my area of specialization.

Road Section

The section of CPG North Avenue located in front of the Coca Cola Bottling Plant up to corner Peñaflor St. and CPG North was constructed way back in 1984 or 1985. This section of the road was not touched by the Hanjin Construction when they constructed the circumferential road.

When it was constructed in 1984, the project engineer was my classmate, the late Engr. Salvador Cabalit. I was one of the suppliers of the "anapog (limestone)" to be used as sub-base filling materials. He told me that he had a problem with the estimated volume of filling materials. His estimate was based only on the pavement width because the shouldering would be in a later appropriation. As it turned out, there was no "later appropriation." So when the filling materials were spread and compacted to include the shoulders of the road, the surface elevation of the road was lower by almost one meter. This is the reason why the area is still subject to flooding during heavy rains.

Twenty Years Service

After being in service for more than 20 years the Hanjin Construction had the opinion that the road section was still in perfect condition and it was not reconstructed. The Hanjin Construction of course did not know that it would soon be subjected to flooding and be subjected to severe conditions.

Deterioration

With the absence of any outlet for the drainage of CPG Avenue, all the run-off water gathers and floods this particular section of the road.

Every time the place is flooded and heavy trucks will pass over it, I always feel sorry for the road pavement. Why? It is because it was not designed to be subjected for that kind of punishment.

The concrete pavement when poured had a "slump test" of about four (4) inches compared to Hanjin's zero (0) "slump test." In spite of its inferiority compared to Hanjin's standard, the road pavement has still withstood its ground. However, if you will observe closely, the concrete pavement or road surface is already showing signs of erosion.

Undermining

Concrete loves water. So I am not much worried with the concrete pavement. I am very much worried with the process called "undermining." [Note: mine, as in digging for gold.]

The base or under layer material is limestone (anapog). This material will be dissolved by water. Water can enter into the base materials through the unpaved shoulder portion of the road. When heavy trucks passed over the concrete pavement, it will create pressure to eject the water under the pavement. This constant pumping action will create voids under the road pavement or what we call "undermining."

If you will observe closely, you will notice that the concrete pavement near the Sayong's Furniture shop has already sagged. It is a clear indication that undermining is already occurring. In my observation, this deflection of about 2 inches is already at the limit. Once this portion will break all the other concrete pavement will also break and the road will be out of service. When this happens, then our problems will be compounded. We will still have flooding and the road could no longer be used even when dry. The question is who will make the appropriation for another concrete pavement? How about the inconvenience of the people when another construction will be done at this "bottleneck" of CPG Avenue?

Comment

The way I see it, we will be lucky if the road pavement will withstand another year of punishment. Everybody knows that the solution is to let the run-off water drain to the sea. The drainage tunnel already exists. The next step is the actual opening of the outlet. When will it happen? It should be done the soonest possible time or else we will face more expenses and more inconvenience, a situation that ought not to happen. Sa Binisayâ pa, suliran kini nga tinuyóan!

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