About me
Analysis of the Operational Impacts of Left-In Left-Out Intersection/Driveway Treatments - The City of Scottsdale, Arizona contains numerous examples of left-in left-out (LILO) treatments at intersections or driveways. These treatments are typically applied on arterial roadways with medians and consist of a channelizing island in the median which helps direct vehicles turning left both on to and out of minor roads or driveways. This treatment also contains left turn refuges with varying lengths for vehicles turning left out of minor roads/driveways. This treatment is relatively uncommon compared with other intersection treatments, and no known formal study of the operational impacts (i.e. delay, etc.) have not been assessed. Due to this lack of studies, and to better understand the operational impacts of LILO treatments, this study had the primary objective of using a microsimulation software (VISSIM) calibrated with field data, to determine the effects of different major and minor road volumes (and select design features) on the operational performance of LILO sites using sensitivity analysis to make predictive delay models using linear regression to determine when operational performance becomes unacceptable using the Two Way Stop Control LOS scale in the Highway Capacity Manual (HCM) due to there being no existing scale for acceptable Level of Service for LILO intersections. This study developed two models: a total delay model and Back-of-Queue to median delay model which can be used to estimate delay for existing or future volumes, and can be used to compare traditional median opening or signalized intersections using HCM methods to estimate delay for these types of intersections.
