Figure 2: Quadrant Roadway Snapshot in Synchro
Preliminary Operational Analysis Based on the results of the planning level analysis, preliminary op- erational analyses were then completed using Synchro software. The existing base model was created using the collated field data and model parameters were adjusted as needed to replicate field conditions. The various design alternatives analyzed and initial projected results are summarized below: 1. Existing with optimized signal timings 2. Lane assignment change (N-S Shared through/left and left lanes 3. Geometry/ Lane assignment changes (Double protected left for N-S) 4. Full CFI/DLT 5. Quadrant Roadway (South-West) Intersection capacity analyses results are generally designated with the letters A to F for acceptable to failing levels of service (LOS). The ex- isting (base) model operates at failing LOS F with a significant corre- sponding intersection delay of 205.0 seconds. Alternatives 1 to 3 were projected to provide decreases in delay but were not significant enough to improve the failing LOS F while all the approaches and intersections were projected to operate at LOS D or better in Alternatives 4 and 5. Detailed Operational Analysis The operational analysis in VISSIMmicrosimulation software was then completed to provide additional evaluation of the options. Generally, the microsimulation environment also takes into account individual vehicle interaction and provides the opportunity to adjust additional
Figure 3: Full Continuous Flow Intersection (CFI) Snapshot in VISSIM
parameters for model calibration. This analysis was important because it allowed travel speed distribution, high side friction, driver aggres- siveness, and additional vehicle classification data to be considered in the evaluation. The quadrant roadway was eliminated from this analysis due to site constraints. The results are consistent with the preliminary analysis results and also project that the full CFI intersection provides the most significant improvement and would reduce intersection delay by 69 percent and improve the LOS to an acceptable C from the failing LOS F in existing conditions. Considerations and Take-aways The analyses supported the consideration of innovative intersection designs when conventional at-grade intersections experience failing operational performance. This is especially true for locations that may be viable candidates for grade-separated interchange designs but could benefit from the preservation of the land use and roadway corridor classification and accessibility to the roadway quadrants for all road users. Short, medium- and long-term options were also outlined for theAnloga intersection. The short- and medium-term options focused on upgrades to the existing design including optimized signal timing, lane assign- ment changes, and improved pavement marking. It also highlighted the importance of undertaking access management and complete streets assessment of the existing layout for a thorough understanding of pub- lic transit and non-motorized access for inclusion in any viable design options. The long-term recommendation was to consider a CFI, full or partial, and to examine its potential in the context of driver expec- tancy, right-of-way constraints, pedestrian and transit accommodation, signing and markings, supplemental driver education and awareness requirements, overall safety concerns and its impact on and interaction with adjacent signalized intersections.
Table 1: Operational Analysis Summary
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