Definition: This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
Input: Passage: The Richmond area also has two railroad stations served by Amtrak. Each station receives regular service from north of Richmond including Washington, D.C., Philadelphia, and New York. The suburban Staples Mill Road Station is located on a major north-south freight line and receives all service to and from all points south including, Raleigh, Durham, Savannah, Newport News, Williamsburg and Florida. Richmond's only railway station located within the city limits, the historic Main Street Station, was renovated in 2004. As of 2010, the station only receives trains headed to and from Newport News and Williamsburg due to track layout. As a result, the Staples Mill Road station receives more trains and serves more passengers overall. Question: Why does the Main Street Station only receive rail traffic from Newport News and Williamsburg?
Output:
track layout