The Impact of Raising the Maximum Floor Area Ratio on Commuting Congestion (Japanese)

This paper attempts to measure the expected impact of raising the maximum floor area ratio (FAR) allowed in the Marunouchi-Otemachi business district of Tokyo from the current 1000% to 2000% by estimating changes in the degree of commuting congestion and then calculating, in monetary terms, the resulting increase in the cost of worker fatigue. If the FAR is raised to 2000%, the daytime population (i.e., the number of people working) in the district is expected to increase from the current 153,000 to a maximum of 429,000, an increase of 276,000. Based on this projection, the author forecasts changes in the rates of commuting congestion for each station-to-station section of the Tokyo Metropolitan area by making the following two assumptions: 1) the peak concentration ratio (i.e., the ratio of the number of people getting off trains during the one-hour peak commuting time to the total number of people getting off at the same station over an entire day) and the unit of concentration (i.e., the ratio of commuter pass users to the total number of people working in the district) remain unchanged; and 2) people commuting to work in the area subject to the eased FAR regulation continue to live in the same place and use the same commuting route. The results show that the average peak-time congestion rate in the most congested sections along the 34 major commuting routes in the metropolitan area increased from the current 179% to 187%, a rise of 8 percentage points. In fiscal 2000, the corresponding congestion rate stood at 212%. Thus, the expected rise in congestion rates resulting from an easing of the FAR regulation would offset roughly one-fourth of the decrease in congestion from fiscal 2000 to the present. Next, using the worker fatigue cost function estimated by Yamaga and Hatta (2000), the author calculates the increments in the fatigue cost for all the station-to-station sections in the metropolitan area. The annual incremental cost for the metropolitan area totaled ¥43 billion. By route, the JR Tokaido line has the largest incremental cost at ¥7.7 billion. In easing the FAR regulation for the Marunouchi-Otemachi district, the government should, at the same time, provide incentives to encourage railway operators to invest in enhanced transportation capacity - improvements to the safety system to enable greater frequency of service, introduction of more double-decker trains, and so forth - to minimize the negative effects of the relaxation of the FAR regulation.