River Sentry: Will the New Sirens Work? (Part Two)

The new Texas SB3 legislation calls for installation of sirens. What is their purpose?

Flood tragedies and nighttime have a deadly relationship. Approximately 75% of the flood deaths happen at night. Exclude low water crossings and this jumps to 80%. Like a volatile fire triangle, flood tragedies feature a three-ingredient chain: sleep, proximity, and rising water. To prevent the horrors, we must break the chain.  Mother nature owns rising water, and proximity cannot be affected if one is resting so you must attack sleep first. Will the sirens do it?

Commercial Fire Code NFPA 72 Section 18.4.5.1 requires an alarm minimum of 75 Decibels (dB) in each sleeping space. A typical city siren produces around 130 dB. Only 500 feet away, heavy rain absorption, loss over distance, and structure insulation lower the level toward 58 dB, far lower than fire code and unlikely to wake anybody. The new legislation defined these as outdoor sirens so perhaps that’s expected but if so, where is the value? How many people are outdoors at 2AM in a thunderstorm? Most are indoors with AC humming, phones silenced after a busy day in the sun. The rain is loud on the roof and the endangered are deep asleep. This defines the environment.

Our goal and desired effect is to wake people up. Sirens are part of the answer but not as currently envisioned. River Sentry sirens are close, likely not farther than 50-70 feet from any protected sleeping area. Pushing over 135 dB with alert tones, lights, and sirens, the structure internal dB is measured to meet or exceed fire code. This may take several units to cover all spaces. The Vistas Camps installation in Kerr County features 6 RS-1A siren towers covering 7 sleeping structures. The residential Flood Warning Cubes triggered by those towers provide the same effect inside homes up to five miles away.

Waking people up is one issue; the second is resiliency. Antiquated, high maintenance sirens are problematic. In 2021, Germany suffered a 1000-year flood. Many of the sirens installed failed to activate due to blackouts. On October 24th, just a few months after the Texas flooding disasters, the San Marcos City sirens failed to alert during a tornado warning. A server vendor issue was offered for the failure. It is not confidence inspiring.

During Hurricane Helene, Ashville NC lost 80% of the cell phone towers and fiberoptic lines were severed. The power grid was out for days. These are the challenges that any resilient flood warning system must face and overcome. The tyranny of distance, extreme weather, single point failures, slow decision making, and fragile tech could easily turn the new siren project into an expensive error of substitution. 

We owe it to those who were lost to make purposeful changes that are effective and dependable. This will take new technology and a fresh approach, not misplaced loyalty to legacy methods that have repeatedly failed.

Join for Part Three: River Sentry Takes the Black (Part Three)