Description and results of a new method for assessing real-life performance of a UV-C disinfection robot.

Background: Due to the disadvantages of manual disinfection of patient rooms, mobile disinfection robots using ultraviolet C (UV-C) radiation are increasingly being used. Assessing their in situ effectiveness remains challenging. Aim: This study describes a new method to prove adequate in situ disinfection (≥5-log reduction in bacterial load), and uses this method to assess the efficacy of a mobile disinfection robot using UV-C radiation. Methods: Agar plates serving as proxies for smooth surfaces in patient rooms were inoculated with bacterial suspension and placed on various surfaces in a patient room. After irradiation by an automated mobile UV-C robot, reduction in colony growth was determined by comparing the irradiated plates to a reference series of non-irradiated plates, enabling the evaluation of whether an adequate reduction in colony-forming units (CFU's) of ≥5-log was reached on these irradiated surfaces. Findings: The new technique described here proved a successful method for demonstrating an in situ ≥5-log reduction in CFU's for five different bacterial pathogens. Of the 32 plates placed on UV-accessible surfaces, 31 showed an adequate reduction in CFU's of ≥5-log. One plate could not be assessed. Conclusion: Inoculated agar plates placed in patient rooms before irradiation and subsequently compared to a reference series can be used to assess in situ efficacy of mobile disinfection robots using UV-C radiation. Our findings support the idea that UV-C robots, used adjunctively to conventional manual washing and disinfection, may achieve adequate bacterial load reduction on UV-accessible smooth surfaces in patient rooms for a selected subset of pathogens.

Increase in gut permeability and oxidized ldl is associated with post-acute sequelae of SARS-CoV-2.

Background: Post-acute sequelae of SARS-CoV-2 (PASC) is marked by persistent or newly developing symptoms beyond 4 weeks of infection. Investigating gut integrity, oxidized lipids and inflammatory markers is important for understanding PASC pathogenesis. Methods: A cross-sectional study including COVID+ with PASC, COVID+ without PASC, and COVID-negative (COVID-) participants. We measured plasma markers by enzyme-linked immunosorbent assay to assess intestinal permeability (ZONULIN), microbial translocation (lipopolysaccharide-binding protein or LBP), systemic inflammation (high-sensitivity C-reactive protein or hs-CRP), and oxidized low-density lipoprotein (Ox-LDL). Results: 415 participants were enrolled in this study; 37.83% (n=157) had prior COVID diagnosis and among COVID+, 54% (n=85) had PASC. The median zonulin among COVID- was 3.37 (IQR: 2.13, 4.91) mg/mL, 3.43 (IQR: 1.65, 5.25) mg/mL among COVID+ no PASC, and highest [4.76 (IQR: 3.2, 7.35) mg/mL] among COVID+ PASC+ (p<.0001). The median ox-LDL among COVID- was 47.02 (IQR: 35.52, 62.77) U/L, 57.24 (IQR: 40.7, 75.37) U/L among COVID+ No PASC, and the highest [76.75 (IQR: 59.95, 103.28) U/L] among COVID+ PASC+ (p<.0001). COVID+ PASC+ was positively associated with zonulin (p=0.0002) and ox-LDL (p<.0001), and COVID- was negatively associated with ox-LDL (p=0.01), compared to COVID+ No PASC. Every unit increase in zonulin was associated with 44% higher predicted odds of having PASC [aOR: 1.44 (95%CI: 1.1, 1.9)] and every one-unit increase in ox-LDL was associated with more than four-fold increased odds of having PASC [aOR: 2.44 (95%CI: 1.67, 3.55)]. Conclusions: PASC is associated with increased gut permeability and oxidized lipids. Further studies are needed to clarify whether these relationships are causal which could lead to targeted therapeutics.

Management of extracranial carotid artery stenosis during endovascular treatment for acute ischaemic stroke: results from the MR CLEAN Registry.

BACKGROUND: The optimal management of ipsilateral extracranial internal carotid artery (ICA) stenosis during endovascular treatment (EVT) is unclear. We compared the outcomes of two different strategies: EVT with vs without carotid artery stenting (CAS). METHODS: In this observational study, we included patients who had an acute ischaemic stroke undergoing EVT and a concomitant ipsilateral extracranial ICA stenosis of ≥50% or occlusion of presumed atherosclerotic origin, from the Dutch Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) Registry (2014-2017). The primary endpoint was a good functional outcome at 90 days, defined as a modified Rankin Scale score ≤2. Secondary endpoints were successful intracranial reperfusion, new clot in a different vascular territory, symptomatic intracranial haemorrhage, recurrent ischaemic stroke and any serious adverse event. RESULTS: Of the 433 included patients, 169 (39%) underwent EVT with CAS. In 123/168 (73%) patients, CAS was performed before intracranial thrombectomy. In 42/224 (19%) patients who underwent EVT without CAS, a deferred carotid endarterectomy or CAS was performed. EVT with and without CAS were associated with similar proportions of good functional outcome (47% vs 42%, respectively; adjusted OR (aOR), 0.90; 95% CI, 0.50 to 1.62). There were no major differences between the groups in any of the secondary endpoints, except for the increased odds of a new clot in a different vascular territory in the EVT with CAS group (aOR, 2.96; 95% CI, 1.07 to 8.21). CONCLUSIONS: Functional outcomes were comparable after EVT with and without CAS. CAS during EVT might be a feasible option to treat the extracranial ICA stenosis but randomised studies are warranted to prove non-inferiority or superiority.

Estimating the effect of vehicle speeds on bicycle and pedestrian safety on the Georgia arterial roadway network.

Cyclists and pedestrians account for a disproportionate amount of the world's 1.3 million road deaths every year. This is a growing problem in the United Sates where bicyclist and pedestrian fatalities have increased steadily since 2009. A large body of research suggests vehicle speeds are a key contributing factor for crashes. However, few studies of bicycle or pedestrian crash probability incorporate detailed vehicle speed data. This study uses probe vehicle speed data to examine the impact of vehicle speeds on bicycle and pedestrian crashes on the state of Georgia's network of major arterial roadways. The analysis examines 7000 road segments throughout the state in 2017. A Negative Binomial model relates annual crash and speed data on each segment. Models using speed percentiles (85th, 50th and 15th) are contrasted with models using speed differences (85th-50th and 50th-15th percentile). A small set of covariates are included: segment length, number of lanes, Average Annual Daily Traffic, and urbanicity. Results indicate that larger differences in high-end speed percentiles are positively associated with bicycle and pedestrian crash frequency on Georgia arterials. Furthermore, the coefficients on the high end of the speed distribution, measured by the difference in 85th and 50th percentile speeds, have greater magnitude and statistical significance than the low end of the distribution. This research shows a negative relationship between speed and crashes may be flawed, as it does not account for the distributions of speed. The findings in this study suggest that planners and engineers should identify areas with large speed distributions, especially at the high vehicle speeds, and work to reduce the fastest speeds on these roadways. To do so, differences in speed percentiles measured using probe vehicle speeds can be used to determine where high risk areas are located.

A framework for localizing global climate solutions and their carbon reduction potential.

Localized carbon reduction strategies are especially critical in states and regions that lack top-down climate leadership. This paper illustrates the use of coupled systems in assessments of subnational climate solutions with a case study of Georgia, a state located in the southeastern United States that does not have statewide climate goals or plans. The paper illustrates how robust place-specific plans for climate action could be derived from foundational global and national work and by embedding that research into the context of socio-ecological-technological systems. Our replicable methodology advances the traditional additive sectoral wedge analysis of carbon abatement potential by incorporating solution interdependencies and by spanning both carbon sources and sinks. We estimate that a system of 20 solutions could cut Georgia's carbon footprint by 35% in 2030 relative to a business-as-usual forecast and by 50% relative to Georgia's emissions in 2005. We also produce a carbon abatement cost curve that aligns private and social costs as well as benefits with units of avoided CO2-e. The solutions are affiliated with various social co-costs and co-benefits that highlight societal concerns extending beyond climate impacts, including public health, environmental quality, employment, and equity.

Hidden work in hepatopancreaticobiliary surgery: the contemporary demands of non-operative patient management.

BACKGROUND: Increasing use is now made of modalities other than surgery (including endoscopy and interventional radiology) in the care of patients with hepatopancreaticobiliary (HPB) diseases. However, the care of and responsibility for patients managed non-operatively continues to reside with surgical services. This investigation was undertaken to quantify the implications of non-operative patient related admissions our HPB unit over a 24 month period. METHODS: Total admissions from Jan 2018-Dec 2019 in a tertiary HPB unit were analyzed to determine HPB-related non-operative admissions. Cost analysis was also undertaken. RESULTS: There were 1528 admissions in 1029 patients for non-operative indications out of a total of 2576 admissions to the HPB unit. Of these, 707 were for diagnoses related to underlying HPB or upper gastrointestinal diagnoses. Patients were primarily treated with an interventional radiology procedure (n = 180), diagnostic or therapeutic endoscopy (n = 287), palliation (n = 57), symptomatic management (n = 152), other (n = 31). Patient age ≥80 (p < 0.05), acute admission (p < 0.01) and the presence of a stage 4 cancer diagnosis (p < 0.01) were associated with non-operative admission. CONCLUSION: Over half of patient admissions are for non-operative management. The contemporary HPB unit is responsible for providing surgical intervention as well as coordinating multidisciplinary care of patients with HPB disease.

Translating a Global Emission-Reduction Framework for Subnational Climate Action: A Case Study from the State of Georgia.

Subnational entities are recognizing the need to systematically examine options for reducing their carbon footprints. However, few robust and comprehensive analyses are available that lay out how US states and regions can most effectively contribute. This paper describes an approach developed for Georgia-a state in the southeastern United States called "Drawdown Georgia", our research involves (1) understanding Georgia's baseline carbon footprint and trends, (2) identifying the universe of Georgia-specific carbon-reduction solutions that could be impactful by 2030, (3) estimating the greenhouse gas reduction potential of these high-impact 2030 solutions for Georgia, and (4) estimating associated costs and benefits while also considering how the solutions might impact societal priorities, such as economic development opportunities, public health, environmental benefits, and equity. We began by examining the global solutions identified by Project Drawdown. The resulting 20 high-impact 2030 solutions provide a strategy for reducing Georgia's carbon footprint in the next decade using market-ready technologies and practices and including negative emission solutions. This paper describes our systematic and replicable process and ends with a discussion of its strengths, weaknesses, and planned future research.

Prehospital Ketamine Use for Rapid Sequence Intubation: Are Higher Doses Associated With Adverse Events?

OBJECTIVE: Ketamine for rapid sequence intubation (RSI) is typically dosed at 1 to 2 mg/kg intravenously. The need to ensure dissociation during RSI led some to administer ketamine at doses greater than 2 mg/kg. This study assessed associations between ketamine dose and adverse events. METHODS: This multisite, retrospective study included adult subjects undergoing RSI with intravenous ketamine. Subjects were categorized into 2 groups: a standard ketamine dose (≤ 2 mg/kg intravenously) or a high dose (> 2 mg/kg intravenously). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for adverse events. RESULTS: Eighty subjects received standard-dose ketamine, and 50 received high-dose ketamine. The high-dose group had a significantly (P < .05) higher proportion of trauma patients, were younger, and had higher predose blood pressure compared with the standard-dose group. High-dose ketamine was associated with greater odds of adverse events including hypotension (OR = 7.0; 95% CI, 3.0-16.6), laryngospasm (OR = 10.8; 95% CI, 1.3-93.4), bradycardia (OR = 7.5; 95% CI, 1.5-36.6), repeat medications (OR = 12.9; 95% CI, 1.5-107.9), oxygen desaturation (OR = 6.0; 95% CI, 1.8-19.9), multiple attempts (OR = 3.2; 95% CI, 1.5-6.8%), and failed airway (OR = 3.6; 95% CI, 1.0-12.7). CONCLUSION: Ketamine at higher doses was associated with increased odds of adverse events. Studies assessing adverse events of ketamine at lower than standard doses in shock patients are needed.

Treatment of gastric adenocarcinoma at a New Zealand centre: meeting the challenges of a low volume country.

BACKGROUND: Surgical treatment of gastric cancer in New Zealand is challenging because of a low annual incidence of 400 patients and population dispersal over a wide area with little data on regional treatment trends and outcomes. This investigation was undertaken to evaluate the surgical outcomes of gastric cancer patients presenting to a single upper gastrointestinal centre (WDHB, Waitemata District Health Board) and to compare these to national and international standards. METHODS: Data on 135 patients with histologically proven gastric adenocarcinoma presenting between January 2010 and December 2014 were reviewed and compared with nationally available procedural volume data. RESULTS: Sixty of 135 patients were resected (resection rate 44%) and 75 patients were managed with palliative chemotherapy/symptomatic care alone. Twenty-six patients (43%) received adjuvant or neoadjuvant chemotherapy and only two patients (3%) underwent laparoscopic resection. In resected patients, 90-day mortality was 1.6%, and 11 patients (18%) developed complications ≥ Clavien-Dindo grade 3. Fifty-two patients (87%) had ≥15 lymph nodes resected and 54 patients (90%) had a histological R0 resection. At median follow-up of 49 months, 30 patients remain alive and disease-free with 20 true 5-year disease-free survivors. National data between 2010 and 2014 showed WDHB performed 20% (338/1710) of gastric resections for all indications in New Zealand. CONCLUSION: While WDHB is an internationally low volume centre for gastric cancer, surgical outcomes benchmark satisfactorily to international standards. New Zealand's national treatment standards should set aspirational goals for gastric cancer treatment and have a clear strategy to address issues of surgical volume and national service provision.

MOVES-Matrix for high-performance on-road energy and running emission rate modeling applications.

The MOVES model was developed by the U.S. Environmental Protection Agency (U.S. EPA) to estimate emissions from on-road mobile sources and nonroad sources in the United States. Coupling high-resolution on-road vehicle activity data with appropriate MOVES emission rates further advances research efforts designed to assess the environmental impacts of transportation design and operation strategies. However, the complicated MOVES interface and slow performance makes it difficult to assess large, regional scale transportation networks and to undertake analyses of large-scale systems that are dynamic in nature. The MOVES-Matrix system develops an initial Large Matrix of MOVES outputs by running MOVES 146,853 times on the PACE high performance computing cluster to generate more than 90 billion emission rates to populate the matrix for a single area with one fuel regime and one inspection and maintenance program. A total of 117 such Large Matrices would be needed for the entire United States. The MOVES-Matrix system developed can be used to conduct the emissions modeling 200-times faster than using MOVES. The hypothetical case study shows that MOVES-Matrix is able to generate the exact same emission results as the MOVES model to ensure the validity for regulatory analysis. The resulting matrix allows users to link emission rates to big data projects and to evaluate changes in emissions for dynamic transportation systems in near-real-time. MOVES-Matrix does not currently estimate emissions from starts, hoteling or evaporative emissions, and the research team is working on MOVES-Matrix version 2 that supports incorporating off-network modeling.Implications: MOVES-Matrix should be of interest to a broad readership including those interested in vehicle emission modeling, near-road air quality modeling, transportation conformity analysis. The paper should also interest engineers who are involved in transportation regulatory and conformity analysis, state implementation plan, and who are seeking an efficient way of conducting regulatory emission modeling and air quality analysis in the United States.

Role of post-operative serum C-reactive protein levels as a predictor of complications in upper gastrointestinal surgery.

BACKGROUND: This study was undertaken to assess the value of C-reactive protein (CRP) in predicting infective complications after elective upper gastrointestinal surgery. METHODS: Demographic data, clinical outcomes and serial CRPs preoperatively to post-operative day (POD) 7 were collected for patients undergoing pancreatectomy, hepatectomy and oesophago-gastrectomy between 2005 and 2016. Areas under the curve (AUC) were used to evaluate diagnostic accuracy per day of measurement. RESULTS: Of the 249 patients, 63 (25.3%) developed infective complications and 25 (10%) developed severe infective complications (≥Clavien-Dindo Grade III). Patients with infective complications trended towards higher CRP levels on POD1-POD4 and had significantly higher CRP levels on POD5 (156 versus 114 mg/dL; P = 0.03), POD6 (146 versus 93 mg/dL; P < 0.01) and POD7 (135 versus 84.6 mg/dL; P < 0.01). CRP had the best diagnostic accuracy for severe infective complications on POD6 (AUC: 0.73) and POD7 (AUC: 0.63). A CRP cut-off of 120 mg/dL on POD6 had a negative predictive value of 96.1% and a CRP cut-off of 80 mg/dL on POD7 had a negative predictive value of 94.9%. CONCLUSION: CRP measurements can be used as a negative predictive marker of infective complications in the first post-operative week after major elective upper gastrointestinal surgery.

Oesophagectomy at a New Zealand regional centre: where to now?

BACKGROUND: This study aims to define contemporary trends in characteristics, costs and management of patients diagnosed with oesophageal adenocarcinoma in New Zealand. METHODS: Clinical, pathological and management data of the 135 patients presenting with histologically proven adenocarcinoma to our institution over a 5-year period (January 2010 to December 2014) was collected. Primary analysis reviewed patient demographics, co-morbidities, treatment strategy and survival. Secondary analysis defined operative outcomes including complications, mortality rates and overall survival to December 2016. RESULTS: Thirty-eight patients underwent oesophago-gastrectomy (resection rate 28%) with curative intent following neoadjuvant chemotherapy with Clavien-Dindo ≥3 complications in 17 patients (46%). Actuarial survivals from surgery at 1, 3 and 5 years were (79, 55 and 50%), with 19 patients (54%) alive and disease free at a median follow-up of 26.5 months (range 1-82 months). Overall, this represented one sixth of the national volume of oesophagectomy. Ninety-seven patients were managed non-surgically due to metastatic or advanced local disease (n = 64), co-morbid status (n = 27), patients choice (n = 2) and unknown (n = 4). Median survival from diagnosis in non-resected patients was 9 months (range 1-40 months). CONCLUSION: Oesophagectomy remains a challenging procedure for any institution, although good results can be achieved. Foci for referral are emerging in New Zealand for the surgical management of oesophageal cancer.

Can post encroachment time substitute intersection characteristics in crash prediction models?

INTRODUCTION: Transportation safety analyses have traditionally relied on crash data. The limitations of these crash data in terms of timeliness and efficiency are well understood and many studies have explored the feasibility of using alternative surrogate measures for evaluation of road safety. Surrogate safety measures have the potential to estimate crash frequency, while requiring reduced data collection efforts relative to crash data based measures. Traditional crash prediction models use factors such as traffic volume, sight distance, and grade to make risk and exposure estimates that are combined with observed crashes, generally using an Empirical Bayes method, to obtain a final crash estimate. Many surrogate measures have the notable advantage of not directly requiring historical crash data from a site to estimate safety. Post Encroachment Time (PET) is one such measure and represents the time difference between a vehicle leaving the area of encroachment and a conflicting vehicle entering the same area. The exact relationship between surrogate measures, such as PET, and crashes in an ongoing research area. METHOD: This paper studies the use of PET to estimate crashes between left-turning vehicles and opposing through vehicles for its ability to predict opposing left-turn crashes. By definition, a PET value of 0 implies the occurrence of a crash and the closer the value of PET is to 0, the higher the conflict risk. RESULTS: This study shows that a model combining PET and traffic volume characteristic (AADT or conflicting volume) has better predictive power than PET alone. Further, it was found that PET may be capturing the impact of certain other intersection characteristics on safety as inclusion of other intersection characteristics such as sight distance, grade, and other parameters result in only marginal impacts on predictive capacity that do not justify the increased model complexity.

From scratch: developing a hepatic resection service for metastatic colorectal cancer.

BACKGROUND: Waitemata District Health Board has New Zealand's largest catchment and busiest colorectal unit. The upper gastrointestinal unit was established in 2005, in part to provide a hepatic resection service for patients with colorectal carcinoma metastatic to the liver. The aim of this investigation was to report on quality indicators for the hepatic resection of colorectal carcinoma in the development of a regional resection service. METHODS: Prospectively collected data on patients undergoing hepatic resection for colorectal carcinoma between 2005 and 2014 was reviewed and correlated with costing data and national hepatic resection rates. RESULTS: A total of 123 patients underwent 138 hepatic resections for metastatic colorectal cancer with a median hospital stay of 8 days (range 4-37 days), a zero 30-day mortality and a median cost of NZ$21 374 for minor hepatectomy and NZ$43 133 for major hepatectomy. Actuarial 5-year disease-free survival was 44%, with 28 patients alive and disease free at 5 years post-resection. Median overall survival was not reached. Review of national hepatic resection rates indicate that Waitemata District Health Board performs one sixth of all hepatic resections in New Zealand and that this treatment modality may be underutilized in the management of patients with metastatic colorectal cancer. CONCLUSION: A regional hepatic resection centre for colorectal metastases can be established in areas of population need and can provide a high-quality, cost-effective service.

The volume, cost and outcomes of pancreatic resection in a regional centre in New Zealand.

BACKGROUND: The frequency, costs and outcome of pancreatic resection (both pancreaticoduodenectomy and distal pancreatectomy) were reviewed in our own institution and correlated with regional population growth as well as national resection rates and locations. METHODS: Demographic, pathological and outcome data on pancreaticoduodenectomy and distal pancreatectomy were obtained from a prospectively maintained database for the years 2005-2009 and 2010-2014. During this period, the catchment population grew from 460 000 to 567 000. Costing information was obtained from the hospital-independent costing and coding committee, and the locations and rates of pancreatic resection were obtained by interrogating the national minimum dataset. RESULTS: A total of 41 pancreatectomies (29 pancreaticoduodenectomy, 12 distal pancreatectomy) were performed between 2005 and 2009, increasing to 84 pancreatectomies (55 pancreaticoduodenectomies, 27 distal pancreatectomies and two total pancreatectomies) between 2010 and 2014. This constituted one sixth of the national volume of pancreatic resections. There was no difference in patient demographics or indications for resection between the two time periods; however, portal vein resection was used more frequently in the second period. Margin positivity rate decreased (7 of 41 versus 8 of 84) and lymph node harvest increased (median 8 nodes versus median 15 nodes) between the two time periods. Overall 30-day mortality was 1.6%. CONCLUSION: In New Zealand, regional rates of pancreatic resection reflect regional population demands, and institutional growth is driven by local population requirements. Institutional growth can be achieved with the maintenance of internationally accepted outcomes and quality indicators.

Endoscopic assessment and management of sporadic duodenal adenomas: The results of single centre multidisciplinary management.

AIM: To review the role of multidisciplinary management in treating sporadic duodenal adenomas (SDA). METHODS: SDA managed at North Shore Hospital between 2009-2014 were entered into a prospective database. Pathology, endoscopic and surgical management as well as follow up were reviewed. RESULTS: Twenty-eight patients (14 male: Median age 68 years) presented with SDA [18 were classified as non ampullary location (NA), 10 as ampullary location (A)]. All SDA were diagnosed on upper gastrointestinal endoscopy and were imaged with a contrast enhanced CT scan of the chest, abdomen and pelvis. Of the NA adenomas 14 were located in the second part, 2 in the first part and 2 in the third part of the duodenum. Two patients declined treatment, 3 patients underwent surgical resection (2 transduodenal resections and 1 pancreaticoduodenectomy), and 23 patients were treated with endoscopic mucosal resection (EMR). The only complication with endoscopic resection was mild pancreatitis post procedure. Patients were followed with gastroduodenoscopy for a median of 22 mo (range: 2-69 mo). There were 8 recurrences treated with EMR with one patient proceeding to pancreaticodeuodenectomy because of high grade dysplasia in the resected specimen and 2 NA recurrences were managed with surgical resection (distal gastrectomy for a lesion in the first part of the duodenum and a transduodenal resection of a lesion in the third part of the duodenum). CONCLUSION: SDA can be treated endoscopically with minimal morbidity and piecemeal resection results in eradication in nearly three quarters of patients. Recurrent SDA can be treated with endoscopic reresection with surgical resection indicated when the lesions are large (> 4 cm in diameter) or demonstrate severe dysplasia or invasive cancer.

Safety impacts of bicycle infrastructure: A critical review.

PROBLEM AND METHOD: This paper takes a critical look at the present state of bicycle infrastructure treatment safety research, highlighting data needs. Safety literature relating to 22 bicycle treatments is examined, including findings, study methodologies, and data sources used in the studies. Some preliminary conclusions related to research efficacy are drawn from the available data and findings in the research. RESULTS AND DISCUSSION: While the current body of bicycle safety literature points toward some defensible conclusions regarding the safety and effectiveness of certain bicycle treatments, such as bike lanes and removal of on-street parking, the vast majority treatments are still in need of rigorous research. Fundamental questions arise regarding appropriate exposure measures, crash measures, and crash data sources. PRACTICAL APPLICATIONS: This research will aid transportation departments with regard to decisions about bicycle infrastructure and guide future research efforts toward understanding safety impacts of bicycle infrastructure.

Understanding the emission impacts of high-occupancy vehicle (HOV) to high-occupancy toll (HOT) lane conversions: Experience from Atlanta, Georgia.

Converting a congested high-occupancy vehicle (HOV) lane into a high-occupancy toll (HOT) lane is a viable option for improving travel time reliability for carpools and buses that use the managed lane. However, the emission impacts of HOV-to-HOT conversions are not well understood. The lack of emission impact quantification for HOT conversions creates a policy challenge for agencies making transportation funding choices. The goal of this paper is to evaluate the case study of before-and-after changes in vehicle emissions for the Atlanta, Georgia, I-85 HOV/HOT lane conversion project, implemented in October 2011. The analyses employed the Motor Vehicle Emission Simulator (MOVES) for project-level analysis with monitored changes in vehicle activity data collected by Georgia Tech researchers for the Georgia Department of Transportation (GDOT). During the quarterly field data collection from 2010 to 2012, more than 1.5 million license plates were observed and matched to vehicle class and age information using the vehicle registration database. The study also utilized the 20-sec, lane-specific traffic operations data from the Georgia NaviGAtor intelligent transportation system, as well as a direct feed of HOT lane usage data from the State Road and Tollway Authority (SRTA) managed lane system. As such, the analyses in this paper simultaneously assessed the impacts associated with changes in traffic volumes, on-road operating conditions, and fleet composition before and after the conversion. Both greenhouse gases and criteria pollutants were examined. IMPLICATIONS: A straight before-after analysis showed about 5% decrease in air pollutants and carbon dioxide (CO2). However, when the before-after calendar year of analysis was held constant (to account for the effect of 1 yr of fleet turnover), mass emissions at the analysis site during peak hours increased by as much as 17%, with little change in CO2. Further investigation revealed that a large percentage decrease in criteria pollutants in the straight before-after analysis was associated with a single calendar year change in MOVES. Hence, the Atlanta, Georgia, results suggest that an HOV-to-HOT conversion project may have increased mass emissions on the corridor. The results also showcase the importance of obtaining on-road data for emission impact assessment of HOV-to-HOT conversion projects.

MOVES-Matrix and distributed computing for microscale line source dispersion analysis.

MOVES and AERMOD are the U.S. Environmental Protection Agency's recommended models for use in project-level transportation conformity and hot-spot analysis. However, the structure and algorithms involved in running MOVES make analyses cumbersome and time-consuming. Likewise, the modeling setup process, including extensive data requirements and required input formats, in AERMOD lead to a high potential for analysis error in dispersion modeling. This study presents a distributed computing method for line source dispersion modeling that integrates MOVES-Matrix, a high-performance emission modeling tool, with the microscale dispersion models CALINE4 and AERMOD. MOVES-Matrix was prepared by iteratively running MOVES across all possible iterations of vehicle source-type, fuel, operating conditions, and environmental parameters to create a huge multi-dimensional emission rate lookup matrix. AERMOD and CALINE4 are connected with MOVES-Matrix in a distributed computing cluster using a series of Python scripts. This streamlined system built on MOVES-Matrix generates exactly the same emission rates and concentration results as using MOVES with AERMOD and CALINE4, but the approach is more than 200 times faster than using the MOVES graphical user interface. Because AERMOD requires detailed meteorological input, which is difficult to obtain, this study also recommends using CALINE4 as a screening tool for identifying the potential area that may exceed air quality standards before using AERMOD (and identifying areas that are exceedingly unlikely to exceed air quality standards). CALINE4 worst case method yields consistently higher concentration results than AERMOD for all comparisons in this paper, as expected given the nature of the meteorological data employed. IMPLICATIONS: The paper demonstrates a distributed computing method for line source dispersion modeling that integrates MOVES-Matrix with the CALINE4 and AERMOD. This streamlined system generates exactly the same emission rates and concentration results as traditional way to use MOVES with AERMOD and CALINE4, which are regulatory models approved by the U.S. EPA for conformity analysis, but the approach is more than 200 times faster than implementing the MOVES model. We highlighted the potentially significant benefit of using CALINE4 as screening tool for identifying potential area that may exceeds air quality standards before using AERMOD, which requires much more meteorology input than CALINE4.