Pacheco Koch was hired to analyze the capacity issues at the intersection of Pecan Street and Dessau Road as a consultant for the City of Pflugerville. The intersection serves as a reliever route when SH 130 has increased congestion, but handling heavy traffic volumes, especially the westbound left turn. The intersection is constrained by two bridges on the south and west legs, which makes widening the intersection expensive. Additionally, the west leg narrows to a three-lane roadway as it goes through downtown Pflugerville and then widens to a six-lane median divided roadway west of downtown. The eastern leg is a four-lane median divided roadway that widens to a six-lane median divided roadway.
CRIS data was pulled to review crashes and it was discovered that 71 crashes had occurred at this intersection in the last three years. Based on these crash records, Pacheco Koch recommended changing the left turn signal phasing to protected only and re-evaluating the clearance intervals. The existing traffic volumes were projected out ten years to develop a mid-term intersection fix. The no-build solution was analyzed against standard signalized improvements and an alternative intersection. The FHWA CAP-X software was utilized as a high-level tool to narrow down the alternatives analyzed. Based on the CAP-X results and site constraints, it was decided to study the displaced left turn for the east and west directions. The analysis determined that the displaced left turn would greatly decrease driver delay.
A schematic of the displaced left turn was created to further refine the capacity analysis based upon geometric constraints for the intersection. Construction cost estimates were developed for each scenario, as well as cost of driver delay based upon the capacity analysis and value of delay developed annually by the Texas A&M Transportation Institute. Based on the benefit to cost ratio, the displaced left turn was recommended.