Change the paragraph to have better consistency:
This would cross over the Fehmarn Belt in the Baltic Sea -- 18 km (11 mi) wide --. Providing a direct link by railway and highway between northern Germany and Lolland.
This would cross over the Fehmarn Belt in the Baltic Sea -- 18 km (11 mi) wide -- hence providing a direct link by railway and highway between northern Germany and Lolland.