The City operates 7 Outdoor Warning Sirens designed to give reliable warning to persons outside . This is because people outdoors may not have the same access to warning and information via the media as those inside do. Also people, often in large numbers, gather outside in parks, playgrounds and ball-fields, etc. They need time to reach shelter and access information via the media. The sirens activate for any major emergency facing the City.
Sirens can provide warning but no details.
Surely sirens penetrate buildings close to siren units. This is a byproduct of the system, not its goal. It is not possible to infer reliable indoor warning via sirens. Newer structures and vehicles are well insulated and more likely to keep out sound. The sirens cannot be made louder in an effort to penetrate buildings since such an increase may pose a danger to the hearing of people who are outdoors.