Simplify the following text for a Grade 8 native English-speaking person.
Original: Russian Railways department - Gorkovskaya Railroad ( Ð `` Ð 3\/4 Ñ Ñ Ð Ð 3\/4 Ð Ñ Ð Ð Ñ Ð Ð Ð '' Ð Ð Ð 1\/2 Ð Ñ Ð Ð 3\/4 Ñ Ð 3\/4 Ð Ð ) , which operates some 5,700 km of rail lines throughout the Middle Volga region ( of which some 1,200 are in Nizhny Novgorod Oblast ) , is headquartered in Nizhny Novgorod .
Simplified: Nizhny Novgorod ( Russian : Ð Ð Ì Ð Ð 1\/2 Ð Ð Ð Ð 3\/4 Ì Ð Ð Ð 3\/4 Ñ Ð 3\/4 Ð , often shortened to Nizhny ) is the fourth largest city in Russia .