McCormack, E., Jensen, M., & Hovde, A. (2009). Lessons from Tests of Electronic Container Door Seals (No. 09-0821).
This research paper estimates carbon dioxide (CO2) emissions and vehicle-miles traveled (VMT) levels of two delivery models, one by trucks and the other by unmanned aerial vehicles (UAVs), or “drones.”
Using several ArcGIS tools and emission standards within a framework of logistical and operational assumptions, it has been found that emission results vary greatly and are highly dependent on the energy requirements of the drone, as well as the distance it must travel and the number of recipients it serves.
Still, general conditions are identified under which drones are likely to provide a CO2 benefit – when service zones are close to the depot, have small numbers of stops, or both. Additionally, measures of VMT for both modes were found to be relatively consistent with existing literature that compares traditional passenger travel with truck delivery.
Growing pressure to limit greenhouse gas emissions is changing the way businesses operate. This paper presents the trade-offs between cost, service quality (represented by time window guarantees), and emissions of an urban pickup and delivery system under these changing pressures. A model, developed by the authors in ArcGIS, is used to evaluate these trade-offs for a specific case study involving a real fleet with specific operational characteristics. The problem is modeled as an emissions minimization vehicle routing problem with time windows. Analyses of different external policies and internal operational changes provide insight into the impact of these changes on cost, service quality, and emissions. Specific consideration of the influence of time windows, customer density, and vehicle choice are included.
The results show a stable relationship between monetary cost and kilograms of CO2, with each kilogram of CO2 associated with a $3.50 increase in cost, illustrating the influence of fuel use on both cost and emissions. In addition, customer density and time window length are strongly correlated with monetary cost and kilograms of CO2 per order. The addition of 80 customers or extending the time window 100 minutes would save approximately $3.50 and 1 kilogram of CO2 per order. Lastly, the evaluation of four different fleets illustrates significant environmental and monetary gains can be achieved through the use of hybrid vehicles.
The results demonstrate there is not a trade-off between CO2 emissions and cost, but that these two metrics trend together. This suggests the most effective way to encourage fleet operators to limit emissions is to increase the cost of fuel or CO2 production, as this is consistent with current incentives that exist to reduce cost, and therefore emissions.
This paper describes the development of a systematic methodology for identifying and ranking bottlenecks using probe data collected by commercial global positioning system fleet management devices mounted on trucks. These data are processed in a geographic information system and assigned to a roadway network to provide performance measures for individual segments. The authors hypothesized that truck speed distributions on these segments can be represented by either a unimodal or bimodal probability density function and proposed a new reliability measure for evaluating roadway performance. Travel performance was classified into three categories: unreliable, reliably fast, and reliably slow. A mixture of two Gaussian distributions was identified as the best fit for the overall distribution of truck speed data. Roadway bottlenecks were ranked on the basis of both the reliability and congestion measurements. The method was used to evaluate the performance of Washington state roadway segments, and proved efficient at identifying and ranking truck bottlenecks.
At the Pacific Highway port of entry between the United States and Canada, typical delays are known to regional carriers and internalized into schedules. Due to their relative infrequency, the largest crossing times are not internalized into schedules and cause significant disruptions to regional supply chains. This technical note describes the recent patterns of very long crossing times (defined as more than 2 h or the largest 1% of crossing times) and explores the relationship between arrival volume and crossing time. To do so, this study uses commercial vehicle crossing time data from GPS technology and volume data from the British Columbia Ministry of Transportation. Results show a weak correlation between border crossing time and arrival volume when considering individual observations, but a stronger correlation when data are aggregated. Results show a high percentage of crossing time can be attributed to sources other than primary booth delay, particularly for the most disruptive, very long crossing times.
This paper presents a method for extracting transit performance metrics from a General Transit Feed Specification’s Real-Time (GTFS-RT) component and aggregating them to roadway segments. A framework is then used to analyze this data in terms of consistent, predictable delays (systematic delays) and random variation on a segment-by-segment basis (stochastic delays). All methods and datasets used are generalizable to transit systems which report vehicle locations in terms of GTFS-RT parameters. This provides a network-wide screening tool that can be used to determine locations where reactive treatments (e.g., schedule padding) or proactive infrastructural changes (e.g., bus-only lanes, transit signal priority) may be effective at improving efficiency and reliability. To demonstrate this framework, a case study is performed regarding one year of GTFS-RT data retrieved from the King County Metro bus network in Seattle, Washington. Stochastic and systematic delays were calculated and assigned to segments in the network, providing insight to spatial trends in reliability and efficiency. Findings for the study network suggest that high-pace segments create an opportunity for large, stochastic speedups, while the network as a whole may carry excessive schedule padding. In addition to the static analysis discussed in this paper, an online interactive visualization tool was developed to display ongoing performance measures in the case study region. All code is open-source to encourage additional generalizable work on the GTFS-RT standard.
The examination of commercial pilot workload often requires the use of controlled simulated studies to identify causal effects. The specific scenarios to consider within a simulator study require an extensive understanding of the safety situations that can occur in flight while also considering the specific training that pilots are provided within a simulated environment. The purpose of this paper is to provide a more systematic approach to scenario identification based on historical data, feasibility of capturing behavioral changes, simulator constraints, and training curricula.
Pickup and delivery operations are an essential part of urban goods movements. However, rapid urban growth, increasing demand, and higher customer expectations have amplified the challenges of urban freight movement. In recent years, the industry has emphasized improving last-mile operations with the intent of focusing on what has been described as the last leg of the supply chain. In this paper, it is suggested that solving urban freight challenges requires an even more granular scale than the last mile, that is, the last 800 ft. The necessary operations in the last 800 ft require integration of diverse stakeholders, public and private infrastructure, and a diverse set of infrastructure users with multiple, varied objectives. That complexity has led to a gap in the needs of delivery operations and the characteristics of receiving facilities (i.e., unloading and loading facilities and pickup–drop-off locations). This paper focuses on accessibility for pickup and drop-off operations, taking a closer look at urban goods movement in the last 800 ft from the final customer. The paper presents and analyzes previously documented approaches and measures used to study the challenges at the proposed scale. Finally, it proposes a more holistic approach to address accessibility for urban pickup–delivery operations at the microscale to help develop more comprehensive urban freight transportation planning.