An Impact of Gas Prices on Transit Demand Using a Time-series Analysis and a Regression Analysis
Abstract Depending most of its energy sources on foreign countries, Korea efforts to reduce energy consumption in transportation. While studies on the relationship between gas price and transportation demand are many in number, most previous studies have focused on automobile and Seoul. This study analyzes the impact of gas price on transit (bus and subway) demand using monthly data and for various metropolitan areas (Seoul, Busan, Daejeon, Daegu and Gwangju). The research utilizes a time-series model and a multiple regression model, and calculates modal demand elasticities of gas price. The result shows that elasticities of subway demand with respect to gas price is higher than those of bus demand. In addition, elasticities of predominantly automobile cities are more likely to be more sensitive to gas price than those of cities with well-structured transit system.국내에서 소비되는 에너지의 대부분을 해외에 의존하고 있는 우리나라는 교통부문에서도 에너지 절감을 위해 많은 노력을 하고 있다 . 휘발유가격과 교통수요와의 관계는 국내외적으로 꾸준히 연구되어 왔으나 국내 선행연구는 승용차 및 수도권 중심으로 연구되어 왔다 . 본 연구에서는 휘발유가격이 대중교통수요에 미치는 영향을 분석하며 월별 자료를 활용하여 대중교통 수단별 (버스, 도시철도) 및 광역권별(수도권, 부산, 대전, 대구, 광주)로 실증적으로 비교분석했다. 분석을 위해 시계열모형과 다중회귀모형을 사용하였으며 회귀모형의 계수를 활용하여 유가에 대한 대중교통수요의 탄력성을 비교하였다 . 유가에 대한 수요탄력성이 버스보다 도시철도가 높게 나타났고 , 대중교통체계가 잘 갖춰진 수도권보다 승용차 의존적인 지방 광역권이 유가에 더 민감한 것으로 나타났다 .
Transit Ridership, Auto Gas Prices, and World Events
U.S. transit ridership research covers a wide field of traveler response factors but is surprisingly limited concerning the impact of auto gas prices. This situation is unfortunate, because gas prices have driven unprecedented growth in transit demand over the past 2 years. The research literature concerning cross-modal market effects of auto gas prices on transit demand is reviewed, including an outline of modeling work conducted in Australia. An analysis of U.S. national transit demand and auto gas trends is presented: the cross-elasticity of demand (e) is modeled in aggregate and separately for U.S. heavy rail, light rail, and commuter rail, and bus. Results indicate that, in aggregate, U.S. transit demand is at the low to medium end of sensitivity to auto gas prices for countries that have a low mode share. This finding is consistent with the lower cost of gas in the United States compared with other countries. The aggregate e has been measured as 0.12 and indicates that total U.S. transit demand will increase by 1.2% for every 10% increase in gas prices. U.S. light rail is particularly sensitive to gas prices, with e values of 0.27 to 0.38. Bus ridership is only slightly sensitive to gas prices (e = 0.04), and heavy rail is higher (0.17), consistent with most international evidence. A longitudinal model of trends has suggested some acceleration in transit mode sensitivity as world events have continuously affected prices; however, the model suggests that the effects since Hurricane Katrina (August 2005) have softened.
Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands
Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses 
in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing 
suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm 
research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor 
removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. 
The NH3 removal of biotrickling filters ranged from -8% to +100% with an overall average of 70%. Minimum empty bed air 
residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water 
discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control 
is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall 
average of 27%. The odor removal of biotrickling filters ranged from -29% to +87% with an overall average of 51%. 
Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal 
efficiency of both acid scrubbers and biotrickling filters.