南京长江大桥

南京长江大桥是中国自主设计和建造的第一座双层式铁路、公路两用桥梁。上层的公路桥长4589米，为双向四车道；下层的铁路桥长6772米，连接原来的津浦铁路和沪宁铁路，使火车过江时间由原来的1.5小时缩短为2分钟。南京长江大桥不仅是中国南北交通的重要枢纽，也是南京的著名景点，它标志着中国桥梁建设的巨大进步，极大地方便了长江两岸的人员往来和物资交流，对经济发展和人民生活水平的提高发挥了重要作用。

参考译文：

Nanjing Yangtze River Bridge is the first double-deck railway and highway bridge designed and built by China. The upper highway bridge is 4589 meters long and has four lanes in both directions, while the lower railway bridge is 6772 meters long, connecting the original Jinpu Railway and the Shanghai-Nanjing Railway. The train crossing time from the original 1.5 hours to 2 minutes. Nanjing Yangtze River Bridge is not only an important hub of north-south traffic in China, but also a famous scenic spot in Nanjing. It has greatly facilitated personnel and material exchanges between the two sides of the Yangtze River and played an important role in economic development and the improvement of people's living standards.