TRANSIT ACCESSIBILITY AS A DETERMINANT OF AUTOMOBILE OWNERSHIP

AUTOMOBILE OWNERSHIP IS GENERALLY ACCEPTED AS THE MOST IMPORTANT DETERMINANT OF THE NUMBER OF TRIPS MADE BY RESIDENTS OF A TRAFFIC ZONE. FOR THIS REASON, THE WAY IN WHICH IT IS FORECAST CAN HAVE A DOMINANT INFLUENCE ON A REGIONAL TRAVEL FORECAST. BECAUSE MOST AUTOMOBILE OWNERSHIP FORECASTS HAVE BEEN INDEPENDENT OF THE TRANSPORTATION ALTERNATIVES BEING TESTED, A MAJOR PORTION OF THE REGIONAL TRAVEL DEMAND WAS SET PRIOR TO THE DISTRIBUTION OF TRAVEL AND THE ALLOCATION AMONG MODES. THIS PAPER ANALYZES THE RELATION BETWEEN TRANSIT ACCESSIBILITY AND AUTOMOBILE OWNERSHIP BY ELIMINATING VARIATIONS IN FAMILY SIZE AND INCOME THROUGH A HOUSEHOLD ANALYSIS. THE FINDINGS SHOW THAT THERE IS A SIGNIFICANT CORRELATION BETWEEN AUTOMOBILE OWNERSHIP AND TRANSIT ACCESSIBILITY FOR ALMOST EVERY CATEGORY OF AUTOMOBILE OWNERSHIP IN AN AREA BY IMPROVING TRANSIT ACCESSIBILITY. SUCH A FINDING COULD HAVE A MAJOR EFFECT ON ESTIMATES OF REGIONAL TRAVEL DEMAND IN AREAS WHERE MAJOR TRANSIT IMPROVEMENTS ARE MADE. FURTHERMORE, REDUCTIONS IN FUTURE REGIONAL AUTOMOBILE OWNERSHIP LEVELS THAT WOULD ACCRUE FROM A MAJOR TRANSIT IMPROVEMENT COULD BE CONSIDERED AS A BENEFIT OF THE TRANSIT IMPROVEMENT. THESE FINDINGS COULD TEND TO MAKE TRANSIT INVESTMENT SLIGHTLY MORE FAVORABLE THAN WHEN THE ONLY BENEFITS CONSIDERED ARE IMPROVED RIDERSHIP FOR EXISTING TRANSIT USERS AND SOME DIVERSION OF TRIPS FROM AUTOMOBILE TO TRANSIT.