| One critical issue facing urban transportation engineers is to enhance safety and efficiency for all modes at signalized intersections without additional infrastructure. To safely accommodate pedestrians, the Highway Capacity Manual prescribes that the parallel vehicular green must be at least equivalent to "WALK" plus the "pedestrian clearance interval (PCI)". A fixed walking speed is used for PCI calculation, which is suboptimal from operations and safety perspectives since some pedestrians walk more slowly or quickly than the design pedestrian. So, the necessary variability is not captured in PCI design. A problem also arises when the required PCI exceeds the parallel vehicular green requirement. Additional green for longer PCI is unnecessary for vehicular efficiency but extracts green from the conflicting phase(s), potentially increasing intersection delay. Fuzzy logic control has proven effective for a complex optimization with multiple objectives, uncertain information, and vague decision criteria. Traffic signal timing lies in this category. With the "dynamic PCI" concept, two signal systems, the extended NEMA scheme and a fuzzy logic controller (FLC), were developed in a microsimulation setting and evaluated against current methods. Both proved to significantly improve operations with most cases. The former lacks in the adaptive ability in fulfilling opposing objectives, while the latter holds comprehensive advantages since it implicitly encompasses safety and human factors in control logic. The FLC finds a compromise among enhancing safety, ameliorating operations, and lessening social cost.;Increasing mid-block crashes lead traffic engineers to make crosswalks safer especially for children and seniors. One solution is to signalize mid-block crosswalks (MBCs) with common schemes. This research presented several alternatives to explore how signalization schemes and geometries affect effectiveness measures from vehicle and pedestrian perspectives. Two-phase timing and an innovative scheme were found significantly improving operations over other options. To model the rage of variables at MBCs, a FLC was developed and evaluated against a "user friendly" counterpart to quantify the potential safety and efficiency benefits. Similarly, it controls MBCs effectively and offers better performances comprehensively.;Given there are numerous intersections and MBCs worldwide, the potential impact of this research could be significant in multiple ways. |
