Construction of a wastewater pipeline under a highway or railway without disrupting the traffic is done by?

The method of boring and jacking is the appropriate technique for constructing a wastewater pipeline under a highway or railway without disrupting traffic. This technique involves boring a hole horizontally through the ground while simultaneously positioning the pipeline in place by pushing or "jacking" it through the tunnel created.

This approach is particularly advantageous in urban areas, where maintaining traffic flow is critical. It allows for the installation of pipelines without the need to excavate large surface areas, thereby minimizing disruption to existing infrastructures such as roads or railways. This method also helps in reducing the environmental impact compared to more disruptive techniques.

In contrast, drag lining, dredging, and embankment excavation involve different processes that may require surface disruptions, making them less suitable for this specific purpose. Thus, boring and jacking stands out as the most effective solution in this context.