Heading to Baguio, I noticed the new lanes in the middle of the NLEX viaduct. The viaduct was actually two bridges constructed over the Candaba Swamp. The soil being too soft for a normal road, the viaduct allowed for two way traffic with each bridge carrying northbound or southbound vehicles. The recall that the original bridges each had 2 lanes plus a shoulder lane. Each now have 3 lanes plus shoulder after expansion years ago. The additional lanes in the middle probably required additional columns to be built with more modern foundations than the original viaduct. The new structures had to be integrated with the older viaducts. Here are photos of the completed sections:

You can go to Google Maps if you want to see what the lanes looked like under construction. Here is a screenshot:

Screenshot

The middle lanes look like they can be used as variable lanes. That is, all or some of the lanes may be used to serve the direction with the heavier traffic. The directions can change depending on the time of day, day of the week or the season. I don’t know at this time though how exactly this can or will be implemented as there are no signs to guide motorists for variable lanes. What signs am I referring to? Here are examples from Bangkok showing overhead signs assigning lanes for the direction with heavier traffic:

A close up of the signs designating lanes for traffic

In the example above, 4 lanes including one counterflow lane are assigned to traffic along the southbound direction.

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