GERT networks have been designed, developed, and used to analyze the following situations: claims processing in an insurance company, production lines, quality control in manufacturing systems, assessment of job performance aids, burglary resistance of buildings, capacity of air terminal cargo facilities, judicial court system operation, equipment allocation in construction planning, refueling of military airlift forces, planning and control of marketing research, planning for contractk negotiations, risk analysis in pipeline construction, effects of funding and administrative strategies on nuclear fusion power plant development, research and development planning, and system reliability. Convert a qualitative description of a system or problem to a generalized network similar to the critical path method—PERT type of network.

Collect the data necessary to describe the functions ascribed to the branches of a network. Combine the branch functions into an equivalent function or functions which describe the network.

Convert the equivalent function or functions into performance measures for studying the system or solving the problem for which the network was created. These might include either the average or variance of the time or cost to complete the network.

Both analytic and simulation approaches have been used to perform step 4 of the procedure. GERTE was developed to analytically evaluate network models of linear systems through an adaptation of signal flow-graph theory. For nonlinear systems, involving complex logic and queuing situations, Q-GERT was developed. In Q-GERT, a simulation of the network is performed in order to obtain statistical estimates of the performance measures of interest.

Unitil Corporation is a public utility holding company system. It is the parent company of eight wholly owned subsidiaries, known as the Unitil System, in New Hampshire and Massachusetts. These subsidiaries form a fully integrated system of energy and service companies that supply some 100,000 customers in New Hampshire and Massachusetts. Unitil's principal business is the purchase, transmission, distribution, and sale of electricity, as well as the distribution and sale of natural gas through its three retail subsidiaries, Concord Electric Company, Exeter & Hampton Electric Company, and Fitchburg Gas and Electric Light Company. Unitil Power Corp. provides wholesale power and transmission services to the system's retail subsidiaries. Unitil Resources Inc. (URI) markets energy, consulting, and other energy-related services to nonaffiliates. Unitil Corporation owns real estate to support the utility business of its affiliates. Until Service Corp. provides centralized support to the system's companies. Usource L.L.C. (a subsidiary of URI) Internet-based energy procurement supplies services to large commercial, industrial, and institutional customers throughout New York and New England. In 1999, Electric Light & Power magazine ranked Unitil's three distribution subsidiaries as first, seventh, and 17th in its list of the nation's 100 lowest-cost distribution companies.

Unitil's history is rooted in its three retail distribution utilities--Fitchburg G & E, Concord Electric, and Exeter & Hampton--three independent, investor-owned utility systems formed through a significant ownership by the Tenney family. More than 100 years after the founding and development of these companies, Unitil emerged as the holding company of a retail electric and gas distribution utility in Massachusetts and of two retail electric distribution utilities in New Hampshire.

In 1852, before the Civil War, the Fitchburg Gas Company began to supply customers in central Massachusetts. Shortly a practical version of the incandescent lamp was invented, Fitchburg Gas bought the Wachusett Electric Light Company and in 1895 changed its company name to Fitchburg Gas and Electric Light Company.

Concord Land and Power Company--incorporated in Concord, New Hampshire in 1892--became the Concord Electric Company in 1901 and acquired Penacook Electric Light Company in 1918. Exeter and Hampton Electric --established in 1908--began by serving customers in 13 towns in Rockingham County, New Hampshire, and then extended its lines to Hampton Falls, Newton, East Kingston, and South Hampton. These companies functioned as private, investor-owned firms to supply electricity in their respective New Hampshire markets. Fitchburg G & E, also a private, investor-owned company, supplied its Massachusetts market with electricity and gas.