The New York City Police Department released a 100-page book Wednesday detailing security plans for city buildings to prevent the effects of possible terrorist attacks.

Police Commissioner Ray Kelly says the report has been tailored to meet the specific needs of the city's high-risk environment. The study creates a three-tier system, which categorizes buildings based on risk of attack.

The book recommends certain strategies, like building wider stairwells and increasing perimeter security, which officials believe will make buildings safer. Kelly says both Citi Field and Yankee Stadium contractors consulted the NYPD when building the new structures.