3.22 Hardware Designed to Tolerate a Single Point of Failure

One Call Center

Practice Statement:

The one call center uses fault-tolerant hardware for its critical path operations, such as ticket taking, database access, and ticket delivery.

Practice Description:

A fault-tolerant system can withstand any single hardware malfunction without any interruption or degradation of service. These systems have the ability to identify the malfunctioning hardware component and permit its replacement while remaining online and processing normal applications. These fault-tolerant systems maximize the probability that the one call center will be able to properly process an excavation request in the event of a failure or malfunction.


  • “Model One Call for the 20th and 21st Century,” AT&T (was available when the practice was created but is no longer available)
  • Existing operating practices from various states’ one call centers


One Call Center One Call Center

Facility Owner Facility Owner

Excavator Excavator

Locator Locator

Project Owner Project Owner

Designer Designer