Closing the Induced Vehicle Travel Gap Between Research and Practice

2017 ◽  
Vol 2653 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Ronald T. Milam ◽  
Marc Birnbaum ◽  
Chris Ganson ◽  
Susan Handy ◽  
Jerry Walters
Keyword(s):  
Academic Research ◽  
Level Of Service ◽  
Department Of Transportation ◽  
Vehicle Miles Traveled ◽  
Highway Capacity ◽  
California Department ◽  
Research And Practice ◽  
Forecasting Models ◽  
Induced Travel ◽  
Travel Forecasting

Several studies have rigorously documented the induced travel effect, in which added highway capacity leads to added vehicle travel. Despite the evidence, transportation planning practice does not fully account for this phenomenon, with the result that estimates of the potential congestion-reducing benefits of added highway capacity may be overstated and estimates of potential environmental impacts understated. In 2015, the California Department of Transportation (Caltrans) sponsored a review of applicable induced vehicle travel research that could inform transportation analysis guidance in response to new laws in California such as Senate Bill 743 (S.B. 743), which prohibits the use of vehicle level of service (LOS) and similar measures as the sole basis for determining significant transportation impacts under the California Environmental Quality Act. Instead, vehicle miles traveled was selected to replace LOS under S.B. 743, and along with the new metric there will be a requirement to account for induced travel effects in analysis of roadway capacity expansion projects. The Caltrans review revealed an inconsistent lexicon in academic research and among practitioners, questions about research applicability, limitations in the sensitivity of travel forecasting models, and confusion about the appropriate use of induced vehicle travel elasticities from research. This paper summarizes the Caltrans review and shares the findings to advance understanding of induced vehicle travel effects and suggest steps for additional research.

Results of California Department of Transportation Litter Management Pilot Study

2001 ◽  
Vol 1743 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Gary Lippner ◽  
John Johnston ◽  
Suzanne Combs ◽  
Kimberly Walter ◽  
David Marx
Keyword(s):  
Pilot Study ◽  
Department Of Transportation ◽  
California Department

Uncertainty in Operational Analysis of Two-Lane Highways

2002 ◽  
Vol 1802 (1) ◽  
pp. 105-114 ◽  
Author(s):  
R. Tapio Luttinen
Keyword(s):  
Input Data ◽  
Travel Speed ◽  
Level Of Service ◽  
Model Parameters ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Operational Analysis ◽  
Percent Time ◽  
Different Types ◽  
Percent Time Spent Following

The Highway Capacity Manual (HCM) 2000 provides methods to estimate performance measures and the level of service for different types of traffic facilities. Because neither the input data nor the model parameters are totally accurate, there is an element of uncertainty in the results. An analytical method was used to estimate the uncertainty in the service measures of two-lane highways. The input data and the model parameters were considered as random variables. The propagation of error through the arithmetic operations in the HCM 2000 methodology was estimated. Finally, the uncertainty in the average travel speed and percent time spent following was analyzed, and four approaches were considered to deal with uncertainty in the level of service.

Comparison of Planning and Operational Analysis Procedures for Signalized Intersections from the Highway Capacity Manual

1996 ◽  
Vol 1555 (1) ◽  
pp. 59-64
Author(s):  
Mark R. Virkler ◽  
Shashi Gannavaram ◽  
Anand Ramabhadran
Keyword(s):  
Level Of Service ◽  
Signal Timing ◽  
Highway Capacity ◽  
Operational Procedure ◽  
Highway Capacity Manual ◽  
Operational Analysis ◽  
Planning Procedure ◽  
Adjustment Factors ◽  
Cycle Lengths ◽  
Traffic Signal Timing

The 1994 update of the Highway Capacity Manual (HCM) includes a planning procedure to estimate the capacity condition of a signalized intersection (Xcm). The planning method results can also be extended to a planning application of the more data-intensive HCM operational procedure to estimate intersection critical flow-to-capacity ratio (Xc) and level of service with only planning-level data. Both the planning procedure and the planning application of the operational procedure involve default adjustment factors and synthesized traffic signal timing (called the “default signal timing”). Data from 166 Missouri intersections were used to determine how well the planning approaches predict operational analysis results. In general, the default signal timings had shorter cycle lengths than the timing plans used at pretimed signals. The shorter cycle lengths led to slightly higher flow-to-capacity ratios, since a higher proportion of each cycle was devoted to lost time. The default signal timings also had more equal flow-to-capacity ratios within critical lane groups. The shorter cycle lengths and more equal flow-to-capacity ratios led to a predicted level of service that was the same or better than that calculated for actual conditions. For the subject intersections, locally calibrated default adjustment factors yielded better predictions of flow-to-capacity ratios and level of service than the HCM defaults. The planning value for Xcm was often less than the actual Xc for operational analysis of actual conditions. This was to be expected since Xcm is based on the maximum allowable cycle length. The HCM planning procedure is expected to receive wide use in a variety of planning and design applications. Calibration of appropriate local default values should improve the accuracy of the planning procedure results.

Findings from the California Vehicle Inventory and Use Survey

2019 ◽  
Vol 2673 (11) ◽  
pp. 349-360 ◽  
Author(s):  
Mobashwir Khan ◽  
Anurag Komanduri ◽  
Kalin Pacheco ◽  
Cemal Ayvalik ◽  
Kimon Proussaloglou ◽  
...  
Keyword(s):  
Data Collection ◽  
Commercial Vehicle ◽  
The United States ◽  
Department Of Transportation ◽  
California Department ◽  
Fine Grained ◽  
Vehicle Type ◽  
Vehicle Data ◽  
Almost All ◽  
Data Collection Effort

This paper describes the findings from the California Vehicle Inventory and Use Survey (CA-VIUS) which was administered between June 2016 and January 2018 and obtained data from a total of 11,118 fleets and 14,790 trucks. The surveys were segmented by registration, geography, vehicle type, and vehicle age, and the data collection effort exceeded sampling targets across almost all segments. The CA-VIUS is the largest statewide commercial vehicle data collection effort in the United States and will replace the 2002 National VIUS in transportation planning and emissions studies throughout California. Currently, the wealth of information provided by the survey is supporting the development of the California Statewide Freight Forecasting Model which is a fine-grained behavioral freight model. This model will allow California Department of Transportation and its partners to make more informed infrastructure and operational investment decisions. The CA-VIUS data will also be useful for researchers and practitioners hoping to understand the impacts and benefits of commercial vehicle movements on air quality, economic activity, safety, and vehicle usage. This paper documents key sampling and survey approaches, but mainly focuses on the key findings observed in the survey. This is a practical paper geared towards practitioners who are seeking to analyze a new VIUS survey and those who wish to implement one of their own.

Delays of Shared-Short Lanes at Unsignalized Intersections

2019 ◽  
Vol 2673 (8) ◽  
pp. 450-462
Author(s):  
Ning Wu ◽  
Werner Brilon
Keyword(s):  
Estimation Procedure ◽  
Level Of Service ◽  
Queuing Systems ◽  
Highway Capacity ◽  
Combined System ◽  
Total Delay ◽  
Average Delay ◽  
Unsignalized Intersections ◽  
Special Case ◽  
Total Average

At unsignalized intersections, both on the major street and on the minor street, there may be short turning lanes alongside the through lanes following downstream from one single lane. This combined system is termed a shared-short lane (SSL). Up to now it has only been possible to calculate the capacity of these lanes at the stop line and the capacity of the diverging point, where the turning lane diverges from the through lane. For the total average delay of the involved individual movements, there is no applicable estimation procedure. As a special case, the shared lane (SL), which is used by several movements without a separate turning lane, must also be reconsidered. This paper presents a new model for the estimation of average delays of SSL with SL as a special case at unsignalized intersections. The model is based on the analogy to standard queuing systems. The results depend on the length of the short lane. The model is validated by simulation. The results demonstrate that the outcome of the models in current highway capacity manuals may be misleading, with the risk of inaccurately classifying the level of service of an intersection. Therefore, there is an urgent need to complete the relevant procedures in highway capacity manuals by more realistic estimation procedures for the total delay at an SSL or an SL. The methods in this paper—even if they are rather complex—are recommended to be incorporated into future versions of highway capacity manuals using some simplifications.

scholarly journals A Novel Methodology for Estimating the Capacity and Level of Service for the New Mega Elliptical Roundabout Intersection

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Ahmed I. Z. Mohamed ◽  
Yusheng Ci ◽  
Yiqiu Tan
Keyword(s):  
Geometric Design ◽  
Level Of Service ◽  
Highway Capacity ◽  
Operation Performance ◽  
Highway Capacity Manual ◽  
Federal Highway ◽  
Green Book ◽  
Traffic Operation ◽  
Gap Acceptance Theory ◽  
Better Than

Mega elliptical roundabout is a new intersection on rural multilane highways. This intersection was developed in a previous paper using simulation data, and the authors found that it is better than interchange (full cloverleaf) in most scenarios of traffic flow. Basically, there are no guidelines or procedures for designing mega elliptical roundabout in AASHTO Green Book, Federal Highway Administration guides, and Highway Capacity Manual. Thus, the purpose of this study is to analyze the traffic operation performance and propose a methodology for calculating the capacity of mega elliptical roundabout and also the level of service by gap acceptance theory. Moreover, this research studied the influence of different values of truck ratios and also different values of a major highway speed on geometric design and traffic operation performance for mega elliptical roundabout. To validate the thoroughness of the proposed methodology, VISSIM simulations were conducted. This research will assist practitioners in determining the appropriate geometric design, assessing mega elliptical roundabout intersections, and making comparisons with other alternatives.

scholarly journals Vehicle and Pedestrian Level of Service in Street Designs with Elements of Shared Space

2020 ◽  
Vol 2674 (9) ◽  
pp. 1084-1096
Author(s):  
Ioannis Kaparias ◽  
Rui Wang
Keyword(s):  
Video Data ◽  
Road User ◽  
Level Of Service ◽  
Highway Capacity ◽  
Vehicle Traffic ◽  
Highway Capacity Manual ◽  
Shared Space ◽  
Before And After ◽  
Traffic Volumes

Inspired by developments in urban planning, the concept of “shared space” has recently emerged as a way of creating a better public realm. This is achieved through a range of streetscape treatments aimed at asserting the function of streets as places by facilitating pedestrian movement and lowering vehicle traffic volumes and speeds. The characteristics of streets with elements of shared space point to the conjecture that traffic conditions and road user perceptions may be different to those on streets designed according to more conventional principles, and this is likely to have an impact on the quality of service. The aim of this paper is, therefore, to perform an analysis in relation to level of service (LOS) and to investigate how this may change as a result of the implementation of street layouts with elements of shared space. Using video data from the Exhibition Road site in London during periods before and after its conversion from a conventional dual carriageway to a layout featuring several elements of shared space, changes in relation to LOS for both vehicle traffic and pedestrians are investigated, by applying the corresponding methods from the 2010 Highway Capacity Manual. The results suggest that streets with elements of shared space provide a much improved pedestrian experience, as expressed by higher LOS ratings, but without compromising the quality of vehicle traffic flow, which, in fact, also sees slight improvements.

Conclusion: setting the agenda for challenging gender based violence in universities

2018 ◽  
pp. 229-240
Author(s):  
Ruth Lewis ◽  
Sundari Anitha
Keyword(s):  
Sexual Harassment ◽  
Academic Research ◽  
Student Activism ◽  
Gender Based Violence ◽  
Future Directions ◽  
Research And Practice ◽  
Policy Practice ◽  
University Communities ◽  
Gender Based ◽  
University Settings

This concluding chapter consolidates some of the book's key themes, such as the analysis of gender based violence (GBV) in university settings as part of the continuum of violence that includes sexual violence and sexual harassment; a gendered understanding of and approach to GBV in universities; and student activism to challenge GBV. It also discusses a jigsaw of responses to tackle GBV, including curriculum-based initiatives such as bystander programmes; the roles of various actors, such as academics, students and feminist communities — in collaboration and as collectives — in this jigsaw of strategies; and gaps and possibilities in current research and practice. Finally, the chapter considers the future directions of activism, policy, practice and research on the issue of GBV in university communities and offers some suggestions about the nature of activism and action that can address this problem as well as the role that academic research can play in this process.

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