scholarly journals MISUSE OF SPEED-BUMPS ON TWO-LANE MAIN RURAL ROADS. A GENERALIZED PRACTICE IN VENEZUELA

2016 ◽  
Author(s):  
Rubén José Calderas Volcanes ◽  
Emilio Germán Moreno González
Keyword(s):  
Travel Time ◽  
Economic Cost ◽  
Level Of Service ◽  
Highway Capacity ◽  
Rural Roads ◽  
Highway Capacity Manual ◽  
Traffic Calming ◽  
Road Section ◽  
Travel Time Distribution ◽  
In Series

Settlements of uncontrolled population on side of road in Venezuela originate the excessive use of traffic speed reducers to mitigate accidents. Misuse of these speed control devices generate problem of functionality in the two-lane main rural roads which requires to be studied to demonstrate its effect on the capacity and level of service. Although other factors may occur (i.e, environmental problems and health), the disproportionate use of speed-bumps worsens circulation quality by increase of travel time as most sensitive parameter. Where this effect not can be reversed it should be made efforts to mitigate speed using another traffic-calming device. The studied stretches are selected according to particular characteristics such as: urban settlement, isolated speed-bump and its installation in series, including case without speed-bumps which guarantees the proper contrast. Video cameras to detect the travel time of vehicles are used in each road section, it allow the measures of other parameters.The travel time distribution with or without speed-bumps and probability distribution that characterizes vehicle movement in each stretch allows the simulation and modeling with the ARENA software. Travel time allows obtain the speed which, together with the volume of traffic, determines the level of service according to the Highway Capacity Manual criterion. The economic cost of substitute measures versus travel time is evaluated and may be useful in decision-making or implementation of better policies by transport governmental institutions.DOI: http://dx.doi.org/10.4995/CIT2016.2016.2255 

scholarly journals Travel Time Estimation on Urban Street Segment

2018 ◽  
Vol 30 (1) ◽  
pp. 115-120 ◽  
Author(s):  
Jelena Kajalić ◽  
Nikola Čelar ◽  
Stamenka Stanković
Keyword(s):  
Travel Time ◽  
Time Estimation ◽  
Travel Speed ◽  
Degree Of Saturation ◽  
Level Of Service ◽  
Travel Time Estimation ◽  
Highway Capacity ◽  
Local Conditions ◽  
Highway Capacity Manual ◽  
Urban Streets

Level of service (LOS) is used as the main indicator of transport quality on urban roads and it is estimated based on the travel speed. The main objective of this study is to determine which of the existing models for travel speed calculation is most suitable for local conditions. The study uses actual data gathered in travel time survey on urban streets, recorded by applying second by second GPS data. The survey is limited to traffic flow in saturated conditions. The RMSE method (Root Mean Square Error) is used for research results comparison with relevant models: Akcelik, HCM (Highway Capacity Manual), Singapore model and modified BPR (the Bureau of Public Roads) function (Dowling - Skabardonis). The lowest deviation in local conditions for urban streets with standardized intersection distance (400-500 m) is demonstrated by Akcelik model. However, for streets with lower signal density (<1 signal/km) the correlation between speed and degree of saturation is best presented by HCM and Singapore model. According to test results, Akcelik model was adopted for travel speed estimation which can be the basis for determining the level of service in urban streets with standardized intersection distance and coordinated signal timing under local conditions.

scholarly journals New Travel Time Reliability Methodology for Urban Arterial Corridors

2021 ◽  
pp. 036119812110061
Author(s):  
Ernest O. A. Tufuor ◽  
Laurence R. Rilett
Keyword(s):  
Travel Time ◽  
Traffic Congestion ◽  
New Technologies ◽  
Travel Time Reliability ◽  
Highway Capacity ◽  
Significance Level ◽  
Highway Capacity Manual ◽  
Travel Time Distribution ◽  
Reliable Performance ◽  
Urban Arterial

The need for reliable performance measures of urban arterial corridors is increasing because of the rise in traffic congestion and the high value of users’ travel time. Consequently, travel time reliability (TTR), which attempts to capture the day-to-day variability in travel times, has recently received considerable research interest. The basis of all TTR metrics is the underlying travel time distribution (TTD) along the given link or corridor. Estimating and forecasting arterial corridor TTDs for TTR analysis is the focus of this paper. This paper proposes a TTR methodology that addresses some of the limitations of the current U.S. state-of-the-art methodology which was published in the 6th edition of the Highway Capacity Manual (HCM6). Specifically, HCM6 can only estimate average TTD and not the population TTD. However, the population TTD is needed for accurate trip decision-making by individual drivers and logistics companies. In addition, HCM6 cannot be used to analyze the effect of new technologies, such as connected and automated vehicles, nor can it be used easily for long corridors or networks. The proposed TTR methodology, which is traffic-microsimulation based, was applied on a 1.16 mi arterial testbed in Lincoln, Nebraska, U.S. It was shown that the proposed TTR methodology, when calibrated, could replicate the empirical population TTD at a 5% significance level. The population TTD could also be transformed into an average TTD that also replicated the corresponding empirical average TTD at a 5% significance level.

Assessment of Arterial Signal Timings Based on Various Operational Policies and Optimization Tools

2021 ◽  
pp. 036119812110111
Author(s):  
Suhaib Al Shayeb ◽  
Nemanja Dobrota ◽  
Aleksandar Stevanovic ◽  
Nikola Mitrovic
Keyword(s):  
Travel Time ◽  
Heavy Traffic ◽  
Future Research ◽  
Signal Timing ◽  
Highway Capacity ◽  
Average Delay ◽  
Highway Capacity Manual ◽  
Simulation And Optimization ◽  
Fort Lauderdale ◽  
Design Engineers

Traffic simulation and optimization tools are classified, according to their practical applicability, into two main categories: theoretical and practical. The performance of the optimized signal timing derived by any tool is influenced by how calculations are executed in the particular tool. Highway Capacity Software (HCS) and Vistro implement the procedures defined in the Highway Capacity Manual, thus they are essentially utilized by traffic operations and design engineers. Considering its capability of timing diagram drafting and travel time collection studies, Tru-Traffic is more commonly used by practitioners. All these programs have different built-in objective function(s) to develop optimized signal plans for intersections. In this study, the performance of the optimal signal timing plans developed by HCS, Tru-Traffic, and Vistro are evaluated and compared by using the microsimulation software Vissim. A real-world urban arterial with 20 intersections and heavy traffic in Fort Lauderdale, Florida served as the testbed. To eliminate any bias in the comparisons, all experiments were performed under identical geometric and traffic conditions, coded in each tool. The evaluation of the optimized plans was conducted based on average delay, number of stops, performance index, travel time, and percentage of arrivals on green. Results indicated that although timings developed in HCS reduced delay, they drastically increased number of stops. Tru-Traffic signal timings, when only offsets are optimized, performed better than timings developed by all of the other tools. Finally, Vistro increased arrivals on green, but it also increased delay. Optimized signal plans were transferred manually from optimization tools to Vissim. Therefore, future research should find methods for automatically transferring optimized plans to Vissim.

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.

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.

scholarly journals Analysis of Component Errors in the Highway Capacity Manual Travel Time Reliability Estimations for Urban Streets

2020 ◽  
Vol 2674 (6) ◽  
pp. 85-97 ◽  
Author(s):  
Ernest O. A. Tufuor ◽  
Laurence R. Rilett
Keyword(s):  
Travel Time ◽  
Time Variability ◽  
Travel Time Reliability ◽  
Travel Times ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Urban Streets ◽  
Estimate Travel Time ◽  
The Difference ◽  
Travel Time Variability

The Highway Capacity Manual 6th edition (HCM6) includes a new methodology to estimate and predict the distribution of average travel times (TTD) for urban streets. The TTD can then be used to estimate travel time reliability (TTR) metrics. Previous research on a 0.5-mi testbed showed statistically significant differences between the HCM6 estimated TTD and the corresponding empirical TTD. The difference in average travel time was 4 s that, while statistically significant, is not important from a practical perspective. More importantly, the TTD variance was underestimated by 70%. In other words, the HCM6 results reflected a more reliable testbed than field measurement. This paper expands the analysis on a longer testbed. It identifies the sources and magnitude of travel time variability that contribute to the HCM6 error. Understanding the potential sources of error, and their quantitative values, are the first steps in improving the HCM6 model to better reflect actual conditions. Empirical Bluetooth travel times were collected on a 1.16-mi testbed in Lincoln, Nebraska. The HCM6 methodology was used to model the testbed, and the estimated TTD by source of travel time variability was compared statistically to the corresponding empirical TTD. It was found that the HCM6 underestimated the TTD variability on the longer testbed by 67%. The demand component, missing variable(s), or both, which were not explicitly considered in the HCM6, were found to be the main source of the error in the HCM6 TTD. A focus on the demand estimators as the first step in improving the HCM6 TTR model was recommended.

Unsignalized Intersection Analysis: Effect of Overlapping Conflicting Traffic Flow on Minor Movement Potential Capacity

1997 ◽  
Vol 1572 (1) ◽  
pp. 86-98
Author(s):  
Christopher J. Fasching
Keyword(s):  
Traffic Flow ◽  
Level Of Service ◽  
Traffic Flows ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Capacity Estimate ◽  
Potential Capacity ◽  
Count Distribution ◽  
Intersection Analysis ◽  
Poisson Count

A particular component of two-way stop unsignalized intersection analyses as presented in the 1994 Highway Capacity Manual (HCM) is described. Specifically, advantages to minor movement capacity are evaluated where traffic flows overlap in multiple lanes. From vehicular arrival data collected by the author, it was determined that the current HCM can significantly underestimate the true potential capacity of minor movements that face multiple lanes of free-flow conflicting traffic. A modification to the HCM procedure is introduced in which an “effective” conflicting flow is calculated on the basis of “blockage” caused by individual lanes of traffic, assuming a Poisson count distribution. In every case examined (24 total), a more accurate potential capacity estimate resulted relative to that determined by the HCM procedure. The modification also resulted in a more accurate level of service in 8 of the 24 cases.

Background for HCM Section on Analysis of Performance of Roundabouts

1998 ◽  
Vol 1646 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Rod Troutbeck
Keyword(s):  
Empirical Model ◽  
Level Of Service ◽  
Gap Acceptance ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Using Data ◽  
Analysis Of Performance

The background to the Highway Capacity Manual (HCM) section on the analysis of the performance of roundabouts is discussed. The paper has two main objectives: to discuss the background of different techniques used to evaluate the level of service and to describe the method included in the HCM. The paper is in two parts. In the first part, the first objective is addressed and the parameters needed to predict both delay and capacity, which in turn are used to evaluate the level of service, are described. It is concluded that the gap acceptance approach is a reasonable one when the performance of roundabouts is predicted using data from uncongested sites. If there are a significant number of roundabouts with congested approaches, an empirical model should be used. It is also concluded that the results from one country cannot be immediately transferred to another. In the second part of the paper, the recommended practice included in HCM Chapter 10 is given.

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