Measurement of level of service for two-lane rural highways

1982 ◽  
Vol 9 (3) ◽  
pp. 385-398 ◽  
Author(s):  
John F. Morrall ◽  
Al Werner
Keyword(s):  
High Speed ◽  
The United States ◽  
Operating Conditions ◽  
Level Of Service ◽  
Cruise Control ◽  
Highway Capacity ◽  
Long Distance ◽  
Rural Highways ◽  
Rural Highway ◽  
Highway System

Rural highway capacity, level of service, and other planning criteria are based on outdated information from the United States where the operating environment and traffic conditions are often quite different from those in Canada. Much of the information on rural two-lane highway overtaking and capacity in the 1965 Highway Capacity Manual (HCM) can be traced to data collected as long ago as 1938. Rural two-lane highway capacity and overtaking concepts in use today have remained essentially unchanged since they first appeared in the 1950 Highway Capacity Manual.This paper presents the findings of an investigation into speed–volume relations, platooning, and overtaking on the primary two-lane rural highway system in Alberta, British Columbia, and the National Parks.The principal findings are: (i) there is little relation between speed and volume over the range of volume observed — up to 1700 vehicles per hour, (ii) the average speed at 1000 vph was found to be 20–25 km/h higher than that predicted in the HCM, (iii) the backward bending portion of the speed–volume curve was not observed, (iv) speed distributions at flow rates of 1200 vph showed a marked increase in speed over that in the HCM, and (v) speed distributions of free-moving vehicles indicate a higher proportion of vehicles travelling at uniform speed.The implication of the findings is that the level of service on two-lane rural highways is much higher than that given in the HCM. This, however, is not the case on most of the primary two-lane highway system in western Canada. Despite low volumes, in the 2500–5000 average daily traffic range, drivers perceive a low level of service. This is attributed to a high proportion of long distance (over 300 km), high-speed trips, in rolling terrain with restricted sight distances, through sparsely developed territory with few intermediate stops. Thus motorists spend most of their journey travelling in high-speed platoons resulting in a high driver workload and a propensity to take risks when overtaking.The paper concludes with a recommendation that a nation-wide effort be mounted to collect speed–volume, headway, platooning, and passing data over the full range of highway operating conditions on a year-round basis. A second recommendation is that provincial highway departments in Canada investigate the concept of platooning and opportunity to overtake for evaluating their two-lane highways. More attention should be given to the education and testing of drivers in the skills of overtaking on rural highways. Also proposed is an evaluation of currently accepted, safe passing sight distances, which may be inadequate for the current operating conditions and traffic mix. Alternatives to four lanes, such as alternating passing lanes with early warning signs (to inform the driver of overtaking opportunities a specified distance ahead in order to reduce driver frustration and prevent dangerous passes), need evaluation as well. The paper concludes with a comment on the possible impact of lower speed limits and vehicle control devices, such as the cruise control, on platooning, overtaking, and level-of-service measurement.

Freeway Weaving: Comparison of Highway Capacity Manual 2000 and Dutch Guidelines

2003 ◽  
Vol 1852 (1) ◽  
pp. 10-18 ◽  
Author(s):  
M. M. Minderhoud ◽  
L. Elefteriadou Elefteriadou
Keyword(s):  
United States ◽  
Sensitivity Analysis ◽  
The United States ◽  
Level Of Service ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Additional Variable ◽  
Different Types ◽  
The U.S ◽  
Capacity Estimates

Weaving sections are a commonly adopted freeway facility both in the United States and in Europe. Knowledge about the capacity and level of service achievable on different types of weaving segments is necessary for the design and management of freeways. Guidelines such as those of the U.S. Highway Capacity Manual (HCM) provide capacity values for different weaving configuration types. The Dutch guidelines for the design of weaving segments are compared with those of the U.S. HCM. Differences between their respective approaches are identified, and a comparison of capacity values is conducted. It was found that there are large differences in capacity estimates for certain weaving configuration types. The results of a sensitivity analysis explain these differences in capacity values to a large extent. This analysis showed that it is important to consider the weaving proportions per leg. Currently, neither the HCM nor the Dutch approach considers different weaving flows per incoming leg. The introduction of an additional variable into the calculation procedure that takes into account the presence of asymmetrical weaving flows is recommended.

Extraction process of charged droplets in ultrasonic electric propulsion system: An experimental study

2019 ◽  
Vol 233 (13) ◽  
pp. 5016-5028
Author(s):  
Weiguo He ◽  
Xiaoming Kang ◽  
Bo Yu ◽  
Xinyu Liu ◽  
Dengshuai Guo ◽  
...  
Keyword(s):  
Flow Rate ◽  
Vibration Frequency ◽  
Electric Propulsion ◽  
High Speed ◽  
Extraction Process ◽  
Operating Conditions ◽  
Experimental Results ◽  
Long Distance ◽  
Charged Droplets ◽  
Ultra High Speed

As a novel propulsion technology, ultrasonic electric propulsion is mainly applied to micro-satellite platforms (<10 kg). In this work, effects of vibration frequency and typical operating conditions on extraction process of charged droplets in ultrasonic electric propulsion are investigated by an ultra-high speed imaging technique. A long-distance microscope coupled with an ultra-high speed camera (NAC HX-6) is also used. A solution of formamide and lithium chloride is employed as propellant. Experimental results show that mean diameters of charged droplets are 43.3 ± 4.2 µm (120 kHz), 76.2 ± 5.8 µm (60 kHz), and 101.4 ± 7.1 µm (25 kHz), respectively. Besides, the theoretical diameter values are calculated, which are close to experimental ones and both values decrease with the increase of vibration frequency. Meanwhile, experimental results indicate that the diameter of charged droplets increases as the propellant flow rate rises, and such effect is obvious when the flow rate is ranging from 3 to 10 ml/h. It is also found that charged droplets are not uniformly accelerated and their motion directions are also divergent.

Framework for Investigation of Level-of-Service Criteria and Thresholds on Rural Freeways

2003 ◽  
Vol 1852 (1) ◽  
pp. 239-245 ◽  
Author(s):  
Jin-Tae Kim ◽  
Kenneth G. Courage ◽  
Scott S. Washburn ◽  
Gina Bonyani
Keyword(s):  
High Speed ◽  
Field Measurements ◽  
Level Of Service ◽  
Traffic Density ◽  
Cruise Control ◽  
Traffic Demand ◽  
Operational Conditions ◽  
Percent Time ◽  
Rural And Urban ◽  
Traffic Stream

The Highway Capacity Manual prescribes level-of-service (LOS) criteria as a function of traffic density to categorize the operational conditions of both rural and urban freeway sections. This density-based level of service is ideally suited to the assessment of urban freeways when the performance must be optimized to meet high traffic demand. There is, however, some question as to whether density is the appropriate indicator of the quality of service on rural freeways, since drivers may think more in terms of psychological or emotional comfort for freeways, which generally serve long, high-speed trips and rarely experience more than moderate congestion levels. Three specific measures are examined that have at least an intuitive relationship to the concept of driver comfort: ( a) acceleration noise, which is a measure of the physical turbulence in the traffic stream; ( b) number and duration of cruise control applications, which could serve as a general indication of driver convenience or inconvenience; and ( c) percent time spent following, which is already accepted as the basis for determining the level of service on rural two-lane highways. The three candidate measures were estimated for a hypothetical section of rural freeway by simulation, using the CORSIM model. The kinematic relationships of individual vehicles within the traffic stream were estimated by postprocessing the simulation data for each second of operation. All of the measures considered in this study have conceptual appeal. All have produced interesting and potentially usable results with respect to their relationships to traffic volume. Although the simulation results are interesting, further studies focusing on driver opinions, behavior, or field measurements, or all three, would likely be necessary to support the development and recommendation of a specific set of LOS criteria that recognizes the differences between the urban and rural freeway driving environments.

Axiomatic Approach To Developing Partial Automation Concepts for Deployment of Automated Highway Systems and Partial Invocation of Vision-Based Lane-Keeping and Adaptive Cruise Control

1998 ◽  
Vol 1651 (1) ◽  
pp. 74-79 ◽  
Author(s):  
H.-S. Jacob Tsao
Keyword(s):  
Axiomatic Approach ◽  
Cruise Control ◽  
Highway Capacity ◽  
Automated Highway Systems ◽  
Pros And Cons ◽  
Capacity Gain ◽  
Automated Highway ◽  
Lane Keeping ◽  
Highway System ◽  
Partial Automation

Discussions about the pros and cons of the automated highway system (AHS) visions are nothing but intellectual exercises unless the issue of how to evolve the current highway system toward this end state can be resolved. The primary motivation for the AHS is its potential for considerable highway capacity gain without major acquisition of right-of-way. Many believe that such capacity gain is possible only when lanes are dedicated to the use of those vehicles equipped for full automation. However, to avoid the empty-lane syndrome, there must exist a sufficient population of automation-equipped vehicles that can use the dedicated lane at once or shortly thereafter. Also, if such automation-equipped vehicles can be used only on such dedicated lanes, few people would purchase such vehicles before dedication of lanes on a network basis, the well-known “chicken-and-egg” problem. In this paper partial-automation concepts are proposed that help solve this chicken-and-egg problem. Because of the futuristic nature of the AHS, many technological and nontechnological questions cannot be answered definitely. Assumptions must first be made about the likely or reasonable answers to such questions and then requirements derived for partial-automation concepts based on these assumptions. The goal is for the inferencing process to be rigorous and correct so that only the assumptions are to be debated. The author believes that the assumptions made are reasonable and therefore that the requirements for partial-automation concepts and the actual partial-automation concepts proposed are necessary. Most important, it is hoped that this approach will facilitate a more rigorous process in exchanging ideas and debating AHS deployment issues.

Evaluation of a Large Zero-Emission High-Speed Passenger Vessel

2021 ◽  
Author(s):  
Orin K. Kierczynski ◽  
James A. Towers ◽  
Kurtis A. Jankowski
Keyword(s):  
United States ◽  
Fuel Cell ◽  
High Speed ◽  
The United States ◽  
Operating Conditions ◽  
Hydrogen Fuel Cell ◽  
Hydrogen Fuel ◽  
Zero Emission ◽  
Passenger Vessel ◽  
Carbon Based

With an increasing emphasis on emission restrictions and environmental impact of carbon-based energies, transportation industries are rapidly focusing on research, development, and implementation of zero-emission fuels and technologies. In the United States, the maritime industry provides key transportation services for people and goods. Immediate and future legislation at the state and federal levels are beginning to push passenger vessel operators to seek more carbon-neutral propulsion methods and begin the necessary transition towards a zero-emission future. Small high-speed, zero-emission vessel concepts are being introduced in the United States, most notably the SWITCH project of San Francisco. The SWITCH project aims to put the first hydrogen fuel cell e-ferry into service in 2021. To date, the zero-emission fast ferry efforts have focused on smaller passenger vessels. This paper examines the potential design elements and operating conditions required for a large (450 passengers) high-speed vessel to meet zero-emission standards. Key ferry metrics of speed and passenger capacity are studied with this concept hull to compare a zero-emission propulsion system against a more traditional carbon-based system. To account for major project decision factors, the economics/cost and regulatory restrictions of a hydrogen fuel cell system are considered for a high-speed passenger vessel of this scope. A sensitivity analysis is performed to determine the technological and performance gains necessary for fuel cell power to match the current capabilities of carbon-based powers. Future development of zero-emission technologies is discussed to evaluate the continually improving opportunities for such a large high-speed vessel.

Estimation of Percentage of Delayed Vehicles Based on Traffic Variables for Rural Highways

1998 ◽  
Vol 1646 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Manuel G. Romana ◽  
Gemma Lépez
Keyword(s):  
Time Delay ◽  
Level Of Service ◽  
Heavy Vehicles ◽  
Highway Capacity ◽  
Sloping Ground ◽  
Rural Highways ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Explained Variation ◽  
Surrogate Measure

According to the Highway Capacity Manual (HCM), it is possible to quantify level of service for rural highways using a basic parameter: percent time delay. Since this variable cannot be measured, it is proposed in the HCM that the percentage of delayed vehicles (% DV) be used as a surrogate measure. The manual gives no means of predicting or estimating % DV other than a curve relating total % DV to total hourly volume. However, it is worth noting that the methodology proposed in the manual does not use this curve. In any case, there has been to this date no proposal as to the estimation of % DV by traffic direction. The results of an attempt to estimate % DV by direction through multiple correlations are presented. The data were gathered on four highways in the province of Madrid, Spain (M-111, M-501, M-600, and M-607). Measurements were carried out in 3-h periods on plain or slightly sloping ground during daily or weekly peak periods. The average daily traffic and rate of heavy vehicles in 1991 were, sorted chronologically, 9,500 and 6.4 percent for M-607; 9,800 and 5.1 percent for M-600; 8,100 and 8.6 percent for M-111; and 14,400 and 5.0 percent for M-501. Several multiple correlations are offered, and one is chosen that has an accuracy of 0.7964, expressed through the coefficient r2 (the explained variation). The model is % DV (Direction 1) = A * (VDirection1) + B * (VDirection2) + C, with the following numerical values: % DV = 0.0443 * V1 + 0.0096 * V2 + 25.5411.

scholarly journals A quantitative analysis of nozzle surface bound fuel for diesel injectors

2017 ◽  
Author(s):  
Jack Turner ◽  
Dan Sykes ◽  
Guillaume De Sercey ◽  
Viacheslav Stetsyuk ◽  
Martin Gold ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Injection Pressure ◽  
Spreading Rate ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Surface Wetting ◽  
Long Distance ◽  
Coverage Area ◽  
Fluid Behaviour

In a fuel injector at the end of the injection, the needle descent and the rapid pressure drop in the nozzle leads todischarge of large, slow-moving liquid structures. This unwanted discharge is often referred as fuel ‘dribble’ and results in near-nozzle surface wetting, creating fuel-rich regions that are believed to contribute to unburnt hydrocarbon emissions. Subsequent fluid overspill occurs during the pressure drop in the expansion stroke when residual fluid inside the nozzle is displaced by the expansion of trapped gases as the pressure through the orifices is equalised, leading to further surface wetting. There have been several recent advancements in the characterisation of these near nozzle fluid processes, yet there is a lack of quantitative data relating the operating conditions and hardware parameters to the quantity of overspill and surface-bound fuel. In this study, methods for quantifying nozzle tip wetting after the end of injection were developed, to gain a better understanding of the underlying processes and to study the influence of engine operating conditions. A high-speed camera with a long- distance microscope was used to visualise fluid behaviour at the microscopic scale during, and after, the end of injection. In order to measure the nozzle tip temperature, a production injector was used which was instrumented with a type K thermocouple near one of the orifices. Image post-processing techniques were developed to track both the initial fuel coverage area on the nozzle surface, as well as the temporal evolution and spreading rate of surface-bound fluid. The conclusion presents an analysis of the area of fuel coverage and the rate of spreading and how these depend on injection pressure, in-cylinder pressure and in-cylinder temperature. It was observed that for this VCO injector, the rate of spreading correlates with the initial area of fuel coverage measured after the end of injection, suggesting that the main mechanism for nozzle wetting is through the impingement of dribble onto the nozzle. However, occasional observations of the expansion of orifice-trapped gas were made that lead to asignificant increase in nozzle wetting.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4661

High-Speed, Long-Distance Electric Traction

1905 ◽  
Vol 59 (1537supp) ◽  
pp. 24627-24628
Author(s):  
Charles A. Mudge
Keyword(s):  
High Speed ◽  
Long Distance ◽  
Electric Traction

Traffic and speed characteristics on two-lane highways: field study

2003 ◽  
Vol 30 (6) ◽  
pp. 1042-1054 ◽  
Author(s):  
Yasser Hassan
Keyword(s):  
Light Condition ◽  
Operating Speed ◽  
Ambient Light ◽  
Horizontal Curve ◽  
Vehicle Class ◽  
Rural Highways ◽  
Horizontal Alignment ◽  
Heavy Truck ◽  
Traffic Composition ◽  
Rural Highway

Many models have been developed to evaluate the operating speeds on two-lane rural highways. However, provided information usually lacks details essential to assess their applicability at locations other than where they were developed. This paper presents a procedure to interpret raw data collected on three horizontal curve sites of different two-lane rural highway classes in Ontario. The speed observations were categorized into three vehicle classes (passenger car, light truck, and multi-axle heavy truck) and four light condition categories (day, night, and two transition periods). The minimum headway and percentile value to define the operating speed were examined, and a revision of the current practice deemed not warranted. The findings also indicated that operating speeds do not depend on the time or vehicle class. Finally, the horizontal alignment affects the operating speed, but the speeds of the two travel directions on a horizontal curve may differ even with little contribution of the vertical alignment.Key words: highway geometric design, operating speed, traffic composition, traffic counters, ambient light, acceleration, deceleration.

Sign in / Sign up

Export Citation Format

Share Document