This work seeks to supplement the work previously done on the Ultra-Wide Band SSDL Circulator. The technique, Sequentially-Switched Delay Line (SSDL), is applied in this circuit to achieve non-reciprocal behavior using only classical, reciprocal integrated circuit elements. Previous iterations of this project have yielded successful results; showing the ability to achieve wide band circulator performance from on-chip measurements. The control element essential to the performance of the circuit is the appropriate biasing of the gates of the Gallium-Nitride (GaN) Field Effect Transistor (FET) switches. These high-power, high-channel breakdown devices require gate bias ranges spanning 10 V to 0 V. Driving such large gate voltages causes the circuit to draw a large amount of power, on the order of watts. In this work, resonant Inductor-Capacitor (LC) sections were used at the gate drive to boost the switching signal through the resonant gain effect. The resultant work showed that a small input gate drive signal could be boosted by the LC section to the required voltages to drive the GaN FETs. On-chip measured results showed close to a ten-fold reduction in circuit power consumption with no impact on performance. Realistic implementations of this technique are fundamentally limited by the quality factor of the LC section components. Two circuits were fabricated, a 1.25 GHz variant and a 2.5 GHz variant, and are described in this work.

This paper presents the project outcomes and lessons learned from the San Francisco PedSafe, a comprehensive pedestrian safety planning and engineering project funded by the Federal Highway Administration. It assesses the effectiveness of the Phase I pedestrian safety plan targeted to higher-injury areas by evaluating the Phase II implementation of a range of mostly low-to-moderate-cost innovative safety improvements.

A total of 13 countermeasures (comprised of nine general engineering countermeasures and four Intelligent Transportation Systems (ITS) countermeasures) were implemented by the San Francisco Municipal Transportation Agency (SFMTA) and evaluated by the University of California- Berkeley, Traffic Safety Center (TSC) in a three-year period (2004-2007). Regarding the effectiveness of the 13 countermeasures, six were considered generally successful; three were considered less successful and four were considered inconclusive. The six most successful countermeasures included: flashing beacons (with automated and push button actuation), in- street pedestrian signs, video detection to adjust signal timing, pedestrian head starts (leading pedestrian intervals), portable changeable message speed limit signs, and “Turning Traffic Must Yield to Pedestrians” signs A summary of countermeasure evaluation result highlights is also reported.

This paper describes the methodology of countermeasure evaluation, including video data, tools used in data analysis, the advantages and limitations of this method, and possible improvements. In addition, general lessons learned of countermeasure implementation, as well as recommendations for further research are also described.

This report evaluates the SR2S program for a number of mandated issues: (i) The effectiveness of the program in reducing crashes, injuries and fatalities involving children in the vicinity of the projects; (ii) The impact of the program on levels of walking and bicycling to school; and (iii) The safety benefits of the program in comparison with other highway safety programs.

In the last decade, there has been an increased focus in California on encouraging children to walk and bicycle to school safely. In 1999, the California Legislature created the Safe Routes to School (SR2S) program, authorizing issuance of a competitive grant process for roadway construction projects. There has been an overall decline in the numbers of child pedestrian/bicyclist collisions in California as a whole. When compared with the control areas, the SR2S project areas did not show a greater decline in numbers of collisions. However, it is likely that the number of children walking/bicycling in the SR2S project areas increased over the relevant time frame. When changes in mobility in the program areas are taken into account, the SR2S program appears to be associated with a net safety benefit for affected school age students.

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Conclusions