On any given day during a semester, more than 25,000 people are on Cornell's sprawling square-mile-plus campus of more than 260 buildings. They are not only at computers but in classrooms, vehicles, labs and kitchens. They are caring for animals, the grounds or doing many other tasks that keep Cornell's giant learning machine running.

What if a tornado were about to hit campus or gunshots were fired? How do you warn so many people in so many places to take immediate cover? Cornell is learning; throughout April, university officials tested, assessed and improved its four new siren systems and its emergency text and voice mailing.

To create effective emergency communications, each campus must take into account not only its size and location, but also what works well in a particular area. For example, with four major cell phone carriers in the Ithaca area and many subscribers, Cornell has particular challenges sending text messages to its vast audience.

"The technologies for emergency messaging are still immature," said Richard McDaniel, vice president for risk management and public safety. "Campuses are wrestling with questions of when to use the tools that we have and how to make them most effective."

Cornell's four emergency alert siren/public address (PA) systems underwent a full-scale test April 30 that was "three-quarters successful," according to Joseph Lalley, director of administration and operations for facilities services. Systems on the roofs of Hans Bethe House, and Mary Donlon and Bartels halls worked well. The system on the roof of the Veterinary Medical Center failed, and replacement electronics are being installed.

Cornell Police conduct weekly "silent" tests of the sirens/PA systems. They will undergo another round of full-scale tests May 28.

During this academic year, emergency text messaging was tested or used six times and adjusted each time to improve delivery time. McDaniel and Lalley consider the April 23 test a success -- the delivery rate was 40,000 messages per hour.

Next test is May 28

A second full-scale test of Cornell's emergency alert sirens/public address (PA) system will be conducted Wednesday, May 28 at 1 p.m.

The test will begin with the broadcast of a pre-recorded test message followed by an alert tone that will sound for 60 seconds and a repeat of the pre-recorded message. A sample of the alert tone can be accessed at http://www.epr.cornell.edu.

Preceding the test, from 10 a.m. to 1 p.m., the alert sirens will be calibrated. During this time, tones or short messages such as "Testing. This is a test. Testing 123. Testing." may be heard.

"In earlier tests, we observed delays in the delivery of messages to Verizon customers," Lalley said. "By changing the means by which the text messages are delivered, we were able to vastly improve its delivery rate into the Verizon network to more than 31,000 messages per hour."

The voice-message test on April 23 was also successful with a delivery rate of more than 20,000 messages per hour and a 92 percent hit rate. As expected, some messages failed because of no answers or disconnections.

Emergency voice and text messaging is an opt-in system, and Cornell has one of the highest registration rates in the country, about 58 percent, McDaniel said, with almost 20,000 students, faculty and staff signed up to receive emergency messages. He urges students not yet registered to do so by going to the online Student Center and staff by going to Employee Essentials.

"Voice and text messaging are a good first-strike tool," Lalley said, but emergency messages receive no special priority, and cell phone networks jam rapidly in emergencies. They must be used in conjunction with such other emergency messaging as Mail Blaster, Web page updates and digital signage. He and staff in University Communications are investigating the use of social networking tools (Facebook, MySpace) for emergency messaging.

"Our testing will never be 'over' because assessing and improving our emergency communications tools are an ongoing process," McDaniel said. "With continuous refinement, we are working to ensure that we have the best systems technically and humanly possible."