Sponsor: City of Scottsdale
PI: Dr. Brendan Russo
Co-PI: Dr. Edward Smaglik
Dates: 10/01/2023-10/31/2024
The City of Scottsdale, Arizona contains numerous examples (approximately 60) of left-in left-out (LILO) treatments at intersections or driveways. An aerial view of a typical LILO treatment in the City of Scottsdale is shown in Figure 1. 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. Additionally, the treatment contains a left turn refuge with varying acceleration lengths for vehicles turning left out of minor roads/ driveways (these left-turning vehicles then merge with major road traffic). The LILO treatment is a relatively uncommon intersection treatment compared with others such as right-in right-out (RIRO), and therefore there is limited research regarding the operational impacts of the LILO treatment. While a previous project funded by the City of Scottsdale showed LILO treatments perform well with respect to safety, the operational impacts (i.e. delay, etc.) have not yet been assessed. It is hypothesized that LILO treatments have the potential to improve operations (i.e. reduce delay) for left-turning vehicles by allowing motorists to focus more on one direction of traffic at a time when determining whether gaps in major road traffic are adequate to complete the turn. The City of Scottsdale is interested in conducting a study of their existing LILO sites with the goal of quantifying the operational impacts of the LILO treatment and determining conditions under which this treatment may be advantageous with respect to operations.
To better understand the operational impacts of LILO treatments, this proposed scope of work has the following primary objective: Using microsimulation modeling calibrated with field data, determine the effects of different major and minor road volumes (and select LILO design features) on the operational performance of LILO sites. This will be achieved through a sensitivity analysis with a goal of determining approximate volume thresholds where operational performance at LILO sites becomes unacceptable.