Why should the bridge concrete crash barrier be buried with pipes?

The reason why the bridge concrete anti-collision guardrail should be buried is because the buried pipe is pre-buried, and the bridge concrete anti-collision guardrail should be fixed on it with screws to strengthen the fixation. It shows that when installing the bridge concrete crash barrier, it is necessary to bury the embedded steel pipes firmly in advance, and then fasten them with bolts, so that they will be more firm when applying concrete.