Back in 1995, the company invested in a 1-terabyte Teradata data warehouse, which is a central repository of historical data.
The data is easy to access (using a Web browser) and can be manipulated for decision support.
The warehouse data come from the systems that run NS (i.e., source systems), and once the data is moved from the source systems to the warehouse users can access and use the data without risk of impacting operations.