sentences:  In the south, the rail lines terminate at Port of Chiapas, and Ciudad Hidalgo, with a short dual-gauge spur line to the border city of Ciudad Tecún Umán, Guatemala.In April 2007 the Russian government announced that it was considering building a rail tunnel under the Bering Strait between Chukotka and Alaska.The tunnel, as projected, would be long and would include oil and gas pipelines, fiber optic cables and power lines.