At Risk: The Bay Area Greenbelt

In 2006, Greenbelt Alliance, the Bay Area's land conservation and urban planning organization, published the newest edition of its landmark study on the state of the region's landscapes. The report found that if current development patterns continue, roughly one out of every 10 acres in the entire Bay Area could be paved over in the next thirty years. Today, there are 401,500 acres of greenbelt lands at risk of sprawl development. That includes 125,200 acres at risk within the next 10 years, classified as high-risk land, and 276,200 acres at risk within the next 10 to 30 years, classified as medium-risk land. Around the region, the places at highest risk -- the sprawl hot spots -- include the I-80 corridor in Solano County, the eastern cities in Contra Costa County, Coyote Valley in southern Santa Clara County, the Tri-Valley area of Alameda and Contra Costa Counties, and areas along Highway 101 through Sonoma County

Bay Area Smart Growth Scorecard

The Bay Area Smart Growth Scorecard is a landmark assessment of the planning policies of all 110 cities and counties of the San Francisco Bay Area.Although a city's current development is apparent to anyone who visits it, the policies that guide a city's future development are not so obvious. The Smart Growth Scorecard provides the first view into these policies and the first comparison among them.The Smart Growth Scorecard evaluated 101 cities in seven policy areas:preventing sprawl; making sure parks are nearby; creating homes people can afford; encouraging a mix of uses; encouraging density in the right places; requiring less land for parking; defining standards for good development. On average, Bay Area cities scored 34% (of a possible 100%), meaning cities are doing only a third of what they could be to achieve smart growth.The Smart Growth Scorecard evaluated eight counties (San Francisco is treated as a city) in five policy areas:managing growth; permanently protecting open space; preserving agricultural land; conserving natural resources; and offering transportation choices. On average, Bay Area counties scored 51%.The scores are low overall. But in every policy area, at least one city or county is doing well, whether it is a city that is encouraging walkable neighborhoods, or a county that is preserving its agricultural land. The Association of Bay Area Governments estimates that Bay Area will have one million additional residents by 2020; the Smart Growth Scorecard evaluates how well all the region's jurisdictions are planning for that growth, and how they can do better

Unmanned Aircraft System (UAS) Delegation of Separation in NextGen Airspace

The purpose of this study was to determine the feasibility of unmanned aircraft systems (UAS) performing delegated separation in the national airspace system (NAS). Delegated separation is the transfer of responsibility for maintaining separation between aircraft or vehicles from air navigation service providers to the relevant pilot or flight operator. The effects of delegated separation and traffic display information level were collected through performance, workload, and situation awareness measures. The results of this study show benefits related to the use of conflict detection alerts being shown on the UAS operator's cockpit situation display (CSD), and to the use of full delegation. Overall, changing the level of separation responsibility and adding conflict detection alerts on the CSD was not found to have an adverse effect on performance as shown by the low amounts of losses of separation. The use of conflict detection alerts on the CSD and full delegation responsibilities given to the UAS operator were found to create significantly reduced workload, significantly increased situation awareness and significantly easier communications between the UAS operator and air traffic controller without significantly increasing the amount of losses of separation

Validation of Minimum Display Requirements for a UAS Detect and Avoid System

The full integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS), a prerequisite for enabling a broad range of public and commercial UAS operations, presents several technical challenges to UAS developers, operators and regulators. A primary barrier is the inability for UAS pilots (situated at a ground control station, or GCS) to comply with Title 14 Code of Federal Regulations sections 91.111 and 91.113, which require pilots to see and avoid other aircraft in order to maintain well clear. UAS pilots removal from the flight deck of the aircraft necessitates the development of a UAS-specific system for detecting nearby traffic and displaying traffic information to the pilot to support their ability to maintain an objectively defined DAA well clear threshold from other aircraft. This new UAS-specific function of remaining DAA well clear is called traffic avoidance. The resulting Detect and Avoid (DAA) system, however, will be subject to a collection of requirements that manufacturers will be obligated to meet in order to certify their equipment. RTCA Special Committee 228 (SC-228), a consortium of representatives from government, industry and academia, is responsible for developing and documenting the Minimum Operational Performance Standards (MOPS) for UAS DAA systems. The present study is the final in a series of human-in-the-loop (HITL) experiments designed to explore and test the various display and alerting requirements being incorporated into the DAA MOPS. Whereas the prior DAA HITLs examined a wide variety of DAA display features and concepts, the current experiment aims to validate the latest minimum display requirements for Phase 1 of the DAA MOPS. Rather than test different display concepts, this study tests two configurations of a MOPS-compatible DAA display: a version that is integrated into the primary navigation and control display of the GCS and a version that is physically separated from the primary display. This manipulation tests the draft minimum requirement that allows the DAA traffic display to be a separate, or standalone, configuration. This type of configuration is a more achievable near-term technology solution since it does not stipulate additional certification or integration requirements on UAS manufacturers. However, a standalone display configuration has the potential to result in pilot performance issues resulting from the cognitive costs of switching between the primary DAA display and the primary navigation and control display. This configuration is also particularly susceptible to errors if the displays are in different orientations (e.g., north-up versus track-up). Both the integrated and standalone display configurations were presented to 16 active UAS pilots in a medium-fidelity simulation, which included confederate air traffic controllers and pseudo pilots operating simulated manned traffic. Pilots were tasked with navigating two different mission routes while maintaining DAA well clear with scripted conflicts. Pilot response times (i.e., measured response) and ability to remain DAA well clear are reported. Primary results indicate that both display configurations resulted in favorable response times and well clear rates. While there were clear trends of pilots objectively performing better in the integrated display condition, with several measured response metrics reaching statistical significance, the differences between the two displays were typically moderate. While the primary variable of DAA display location did not have an especially large impact on pilot performance on its own, when examined alongside the type of DAA threat the pilot was facing (a caution-level versus a warning-level alert), the response time benefits associated with the integrated display were amplified. The implications of these American Institute of Aeronautics and Astronautics 2 results on the Phase 1 DAA MOPS and the connection of this data to previous studies is also discussed

Validation of Minimum Display Requirements for a UAS Detect and Avoid System

The full integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS), a prerequisite for enabling a broad range of public and commercial UAS operations, presents several technical challenges to UAS developers, operators and regulators. A primary barrier is the inability for UAS pilots (situated at a ground control station, or GCS) to comply with Title 14 Code of Federal Regulations sections 91.111 and 91.113, which require pilots to see and avoid other aircraft in order to maintain well clear. The present study is the final in a series of human-in-the-loop experiments designed to explore and test the various display and alerting requirements being incorporated into the minimum operational performance standards (MOPS) for a UAS-specific detect and avoid system that would replace the see and avoid function required of manned aircraft. Two display configurations were tested - an integrated display and a standalone display - and their impact on pilot response times and ability to maintain DAA well clear were compared. Results indicated that the current draft of the MOPS result in high-level performance and did not meaningfully differ by display configuration

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

From Elevated Freeways to Surface Boulevards: Neighborhood, Traffic, and Housing Price Impacts in San Francisco

Freeway “deconstruction” marks an abrupt shift in urban policy. Priorities are shifting away from designing cities to enhance mobility toward promoting economic and environmental sustainability, livability, and social equity. This paper investigates the neighborhood, traffic, and housing price impacts of replacing elevated freeways with surface boulevards in two notable yet different corridors of San Francisco: Embarcadero along the city’s eastern waterfront and Central Freeway/Octavia Boulevard serving a predominantly residential neighborhood west of downtown. A combination of informant interviews, literature reviews, and statistical analyses are used in examining neighborhood, traffic, and housing impacts of these two roadway conversions. The research shows freeway conversions generally lead to gentrification of once-declining neighborhoods, although public policies like affordable housing mandates can temper displacement effects. In general, operational and improvements to surface streets along with enhanced transit services and walking environments have accommodated considerable shares of former freeway traffic so as to avoid the traffic nightmares that were predicted when grade-separated freeways were removed. Empirical evidence on residential sales transactions reveals that the dis-amenity effects of proximity to a freeway have for the most part given way to amenity benefits once roadways are converted to nicely landscaped multi-way boulevards. We conclude that freeway-toboulevard conversions, a form of urban re-prioritization that gives more emphasis to neighborhood quality and less to automobility, have yielded net positive benefits without seriously sacrificing transportation performance