The 14 International Conference “RELIABILITY and STATISTICS in TRANSPORTATION and COMMUNICATION – 2014” Proceedings of the 14 th International Conference “Reliability and Statistics in Transportation and Communication” (RelStat’14), 15-18 October 2014, Riga, Latvia, p. 25. ISBN 978-9984-818-70-2 Transport and Telecommunication Institute, Lomonosova 1, LV-1019, Riga, Latvia THE IMPACT OF ACCESSIBILITY ON TRANSPORT INFRASTRUCTURE WITHIN COMMERCIAL SITE Nadezhda Zenina 1 , Yuri Merkuryev 2 1 Riga Technical university Riga, Latvia, 1 Kalku Street nadezda.zenina@inbox.lv 2 Riga Technical university Riga, Latvia, 1 Kalku Street merkur@itl.rtu.lv In the traffic impact studies (micro level) accessibility is affected by different activities within a commercial, office or residential land. Activities include pedestrian and bicycle conditions, transport infrastructure changes, network capacity, level of service within a site. The aim of this paper is to provide better understanding of how transportation infrastructure changes within the commercial site influence on car-based trip generation rates at micro level. Transportation changes include development of new connections to the site: signalized and unsignalized intersections with different allowed traffic movements. Three parameters: demand, supply and readiness were considered and analyzed. Readiness (the number of traffic flows at the connections after changes in geometrical parameters) was determined by Synchro / Simtraffic 6.0 simulation tool with assumption that the level of service of the site connection should be better than D / E. Verification and validation of simulation model were performed. Demand for commercial site was calculated based on ITE trip generation rates (ITE, 2010) taking into account “smart growth” criteria for local conditions (Zenina and Borisovs, 2013). Supply including existing incoming and outcoming traffic flows for the commercial site was observed by the survey (Solvers, 2013). Keywords: Accessibility, simulation, trip generation, traffic impact studies. Introduction Accessibility by Litman (2011) is defined as the ability to reach destination or activity and can include different transportation modes such as motorized and non-motorized. Land use patterns have significant impacts on transportation and accessibility at the macroscopic, mesoscopic and microscopic scales. Development of big commercial centres around cities, tend to increase the travel time, distance and congestion in the area. There are many ways how to improve accessibility connected to destination land use pattern (Abley, 2012), but mostly all of them are connected to possibility to reduce distance, travel time or costs between two points. Some of the ways include improvements in transportation, for example, changing traffic organization, reducing congestions, developing new roads and connections, in mobility, for example, improving public transport service, pedestrian and cycling routes or reducing distance between destinations. Another way in evaluating accessibility lies in understanding of individuals’ perceptions proximity to urban businesses and associated measurement issues (Krizek, Horning, El-Geneidy, 2012). The results of research have showed that in areas where landscape is very complex with a lot of elements and without smooth way to destination, individuals will perceive distances as longer. In the study by Geurs and Wee (2004) four ways of how to identify accessibility measures were considered: infrastructure-based, location-based, person-based and utility-based measures. All these measures are interrelated and are focused on how to reduce travel time or distance travelled by motorized and non-motorized modes and improve walking, cycling and public transport facilities. In this study accessibility is considered with the aim to get better understanding of how transportation infrastructure changes within the commercial site influence on car-based trip generation rates at micro level. Two main things were evaluated: 1) how to measure accessibility for motorized modes on condition that existing access to the commercial site will be redeveloped. Four variants of access organization to the commercial site were analysed: unsignalized access, signalized access with and without allowed left turns and development of new access. 2) how to change the incoming traffic flows to the commercial site after improvements in existing accesses?.