"In addition to being accident prone, extended dump boxes and body walls cause danger to our structures like viaducts and bridges," Leonilo Javier, PNCC tollways group head, said.
The PNCC said numerous accidents, several of which have been fatal, were caused by the extended vehicles hitting tollway structures.
It also cited Section 9 of PD 1958 which defines the permissible weight and dimension of vehicles allowed on the highway.
PD 1958, PNCC said, provides that no motor vehicle operating as a single unit shall exceed the following dimension: overall width of two and a half meters, overall height of four meters, overall length of 10 meters for freight vehicles with two axles, 11 meters for passenger vehicles with two axles and 14 meters for vehicles with three or more axles.
"We will have safety and security officers deployed at entry points to inspect and apprehend those who will not comply with the regulation," Javier said. Pete Laude