ment to normal route planning methods it was believed that compatibility 
was achieved. 
  
Evaluations of the GCARS I System 
GCARS I System design was tested at two areas (9,13,14). Subsequently 
demonstrations were given to practicing highway location engineers. 
Their reactions were generally favorable. 
Sensitivity of the alternatives generated to the factor selected and 
factor weightings employed was often striking. The economy of the 
system was at first not as good as expected. Revisions of some programs 
resulted in some significant improvement however, and subsequently this 
goal was satisfactorily met. The flexibility of the system was also im- 
pressive. It was obvious that once models of various factors were de- 
veloped a number of studies could be undertaken to test (1) changing 
priorities in factors, (2) changing projected route termini, or (3) mod- 
ifying individual models by changing ranking schemes. 
During early evaluations the grid nature of the models and subsequent 
utility networks used by the minimum path programs were questioned. 
However re-evaluation of these concepts indicated that they were the most 
practical alternative available at that time and should be retained. 
Development of New Teaching GCARS Systems 
Due to the favorable response, it was decided to present the GCARS Sys- 
tem to a broader group of engineers and students and obtain their eval- 
uations. Additional programming was required to convert GCARS from a 
research tool to a teaching tool used by a larger number of persons, 
some with little or no background in computer use. 
The development and testing of the models seemed to require close super- 
vision, however once they were checked and approved, the generation of 
alternatives could become the subject of classroom projects. Thus some 
thought was put to the development of conversational, or at least remote, 
entry of requests for the generation of alternatives on a simplified 
basis. The following systems were then developed:- 
1) GCARS II at Purdue University (12) 
2) EASY-GCARS at the University of Toronto 
Both GCARS II and EASY-GCARS sacrificed, to some degree, the goal of 
machine independence to satisfy "customer convenience". 
The GCARS II System 
In 1969 Purdue University developed an interactive computing system, 
called PROCSY, which allowed a large number of remote terminals to 
create, submit and retrieve jobs. A series of specialized computer 
programs were prepared which allowed users to access the GCARS I pro- 
grams and data sets via the PROCSY system. These programs were called 
GCARS II. 
GCARS II proved to be an ideal teaching tool. After ten or fifteen 
minutes instruction, engineers attending a short course were able to