Free flow speed estimation: A probabilistic, latent approach. Impact of speed limit changes and road characteristics

2020 ◽  
Vol 138 ◽  
pp. 283-298
Author(s):  
Ary P. Silvano ◽  
Haris N. Koutsopoulos ◽  
Haneen Farah
Keyword(s):  
Flow Speed ◽  
Free Flow ◽  
Speed Limit ◽  
Speed Estimation ◽  
Free Flow Speed ◽  
Road Characteristics

scholarly journals The Development and Assessment of Free-Flow Speed Models under Heterogeneous Traffic in Facilitating Sustainable Inter Urban Multilane Highways

2020 ◽  
Vol 12 (8) ◽  
pp. 3445
Author(s):  
Lee Vien Leong ◽  
Tuti Azmalia Azai ◽  
Wins Cott Goh ◽  
Mohammed Bally Mahdi
Keyword(s):  
Field Measurements ◽  
Flow Speed ◽  
Heterogeneous Traffic ◽  
Free Flow ◽  
Suitable Model ◽  
Traffic Conditions ◽  
Sustainable Environment ◽  
Road Users ◽  
Free Flow Speed ◽  
Road Characteristics

The desired speed that drivers can drive without being obstructed or influenced by other road users is characterized as free-flow speed. However, free-flow speed can be influenced by other factors such as the characteristics of the vehicle, driver, road conditions, weather, and speed limits. Due to the country’s heterogeneous traffic conditions, this study aims to develop and assess free-flow speed models based on different vehicle classes and road characteristics in Malaysia. Data were sampled at 16 sites of multilane highways in Malaysia. Analyses of free-flow speed were conducted based on individual and grouped vehicle classes. Subsequently, multiple regression analyses were conducted based on these grouped vehicle classes to develop free-flow speed models. The findings show that the model with the grouping of all vehicles, which includes heavy vehicles and motorcycles, is the most suitable model as it yields the best results based on the performance indicators. The development of a free-flow speed model based on local traffic conditions, which can accurately estimate free-flow speed without having to conduct field measurements, is essential for saving time and costs in data collection. The findings from this study will contribute to improving the design of multilane highways and, ultimately, ensuring the sustainable environment of road networks.

scholarly journals Estimating Free-flow Speed from Posted Speed Limit Signs

2011 ◽  
Vol 16 ◽  
pp. 306-316 ◽  
Author(s):  
Matthew D. Deardoff ◽  
Brady N. Wiesner ◽  
Joseph Fazio
Keyword(s):  
Flow Speed ◽  
Free Flow ◽  
Speed Limit ◽  
Free Flow Speed

Surprises from a Field Validation of Speed Estimation Techniques for Air Quality Conformity Analysis

2005 ◽  
Vol 1941 (1) ◽  
pp. 72-80
Author(s):  
John S. Miller ◽  
G. Michael Fitch ◽  
Lance E. Dougald ◽  
Scott R. Kreissler ◽  
David H. Hill
Keyword(s):  
Air Quality ◽  
Travel Speed ◽  
Large Error ◽  
Flow Speed ◽  
Free Flow ◽  
Speed Estimation ◽  
Voc Emissions ◽  
Estimation Techniques ◽  
Metropolitan Planning Organizations ◽  
Free Flow Speed

The air quality conformity process requires travel speed estimation for a horizon year, where often few roadway characteristics are precisely known. This paper presents the results of a study to validate three relatively common speed estimation techniques comparing predicted speeds with speeds measured on specific roadway links and illustrates how disparity in speed predictions affect nitrogen oxide (NOx) and volatile organic compound (VOC) estimates in the MOBILE6 emissions model. The results are intriguing. On average, the mean absolute errors for the three techniques were similar, ranging between 8 and 12 mph. This large error resulted because free-flow speed and capacity from the long-range model were not always representative of the links being studied. Further, the study suggests that the error associated with any of the techniques could be reduced to 4 mph through judicious altering of the default capacity or default free-flow speed for a given class of links, a feasible approach even for large networks. Finally, MOBILE6 testing with Virginia metropolitan data suggests that the differences in speed predictions yield a 2.5% difference in estimated VOC emissions, with one technique overestimating VOC emissions by 1.75% and two underestimating VOC emissions by 0.71%. All three techniques underestimated metropolitan area NOx emissions by less than 2%. Because link-based speed validation efforts are relatively rare within the conformity analysis process, the methodology discussed here should be of interest to smaller metropolitan planning organizations seeking to verify that accurate speeds are used in conformity determination.

Application of Moving Car Observer Method for Measuring Free Flow Speed on Two-lane Highways

2014 ◽  
Vol 69 (6) ◽  
Author(s):  
Othman Che Puan ◽  
Muttaka Na’iya Ibrahim ◽  
Usman Tasiu Abdurrahman
Keyword(s):  
Field Measurement ◽  
Flow Speed ◽  
Operating Conditions ◽  
Free Flow ◽  
Geometric Features ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Free Flow Speed ◽  
The Subject ◽  
Low Traffic

There exists a need to evaluate the performance indicator that reflects the current level of service (LOS) of the subject facility to justify any decision making on expenditures to be made for improving the performance level of a road facility. Free-flow speed (FFS) is one of the key parameters associated with LOS assessment for two-lane highways. Application of a more realistic approach for assessing road’s performance indicators would result in better estimates which could in turn suggest the most appropriate decision to be made (for situations where upgrading is needed); especially, in terms of finance, materials and human resources. FFS is the driver’s desired speed at low traffic volume condition and in the absence of traffic control devices. Its estimation is significant in the analysis of two-lane highways through which average travel speed (ATS); an LOS indicator for the subject road class is determined. The Highway Capacity Manual (HCM) 2010 offers an indirect method for field estimation of FSS based on the highway operating conditions in terms of base-free-flow-speed (BFFS). It is however, recommended by the same manual that direct field FSS measurement approach is most preferred. The Malaysian Highway Capacity Manual (MHCM) established a model for estimating FFS based on BFFS, the geometric features of the highway and proportion of motorcycles in the traffic stream. Estimating FFS based on BFFS is regarded as an indirect approach which is only resorted to, if direct field measurement proved difficult or not feasible. This paper presents the application of moving car observer (MCO) method for direct field measurement of FFS. Data for the study were collected on six segments of two-lane highways with varying geometric features. FFS estimates from MCO method were compared with those based on MHCM model. Findings from the study revealed that FFS values from MCO method seem to be consistently lower than those based on MHCM model. To ascertain the extent of the difference between the FFS values from the two approaches, student t-statistics was used. The t-statistics revealed a P–value of less than 0.05 (P < 0.05) which implies that there is a statistically significant difference between the two sets of data. Since MCO method was conducted under low traffic flow (most desired condition for field observation), it can be suggested that MCO estimates of FFS represent the actual scenario. A relationship was therefore developed between the estimates from the two methods. Thus, if the MHCM model is to be applied, the measured value needs to be adjusted based on the relationship developed between the two approaches.

scholarly journals An Efficient Scheduling of Flyover at Grade Intersection under Mixed Traffic Environment

2021 ◽  
Vol 9 (VI) ◽  
pp. 824-833
Author(s):  
Shradha S. Zanjad
Keyword(s):  
Queue Length ◽  
Fixed Time ◽  
Flow Speed ◽  
Free Flow ◽  
Mixed Traffic ◽  
Time Control ◽  
Traffic Environment ◽  
Free Flow Speed ◽  
Big Cities

A flyover is a bridge constructed along an intersecting highway over an at-grade intersection. It allows two –direction traffic to flow at free flow speed on the bridge. The flyover is one of the methods for solving traffic problems at at-grade junctions on highways including capacity, congestion, long delay and queue length. Traffic signalization at the upgraded intersection often uses the same fixed time control plans, even after the installation of a flyover over the intersection. Most of the flyovers in India are constructed at the junctions on highway bypasses of big cities. The present work deals with a efficient scheduling of flyover at the grade intersection under the mixed traffic environment. From the results and the modeling carried out in the “SIDRA Intersection” software different points are observed. The present work consists of the Proposed Intersection at Rajkamal Square, Amravati.

scholarly journals The Effect of Congestion Pricing Scheme on the Generalized Cost and Speed of a Motorcycle

2016 ◽  
Vol 15 (1) ◽  
pp. 95-106
Author(s):  
Gito SUGIYANTO
Keyword(s):  
Traffic Congestion ◽  
Demand Management ◽  
Congestion Pricing ◽  
Flow Speed ◽  
Free Flow ◽  
Vehicle Speed ◽  
Traffic Jams ◽  
Pricing Scheme ◽  
Free Flow Speed ◽  
Generalized Cost

Traffic congestion is one of the significant transport problems in many cities in developing countries. Increased economic growth and motorization have created more traffic congestion. The application of transportation demand management like congestion pricing can reduce congestion, pollution and increase road safety. The aim of this research is to estimate the congestion pricing of motorcycles and the effect of a congestion pricing scheme on the generalized cost and speed of a motorcycle. The amount of congestion pricing is the difference between actual generalized cost in traffic jams and in free-flow speed conditions. The analysis approach using 3 components of generalized costs of motorcycle: vehicle operating, travel time and externality cost (pollution cost). The approach to analyze the pollution cost is marginal-health cost and fuel consumption in traffic jams and free-flow speed conditions. The value of time based on Gross Regional Domestic Product per capita in Yogyakarta City in October 2012. The simulation to estimate the effect of congestion pricing using Equilibre Multimodal, Multimodal Equilibrium-2 (EMME-2) software. The results of this study show that while the free-flow speed of a motorcycle to the city of Yogyakarta is 42.42 km/h, with corresponding generalized cost of IDR1098 per trip, the actual speed in traffic jams is 10.77 km/h producing a generalized cost of IDR2767 per trip, giving a congestion pricing for a motorcycle of IDR1669 per trip. Based on the simulation by using EMME-2, the effect of congestion pricing will increase on vehicle speed by 0.72 to 8.11 %. The highest increase of vehicle speed occurred in Malioboro Street at 2.26 km/h, while the largest decrease occurred in Mayor Suryotomo Street at north-south direction at 1.07 km/h. Another effect of this application for motorcycles users will decrease the generalized cost by 1.09 to 6.63 %.

scholarly journals Modelling Free Flow Speed on Two-Lane Rural Highways in Bosnia and Herzegovina

2014 ◽  
Vol 26 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Ivan Lovrić ◽  
Dražen Cvitanić ◽  
Deana Breški
Keyword(s):  
Field Survey ◽  
Evaluation Model ◽  
Practical Method ◽  
Flow Speed ◽  
Free Flow ◽  
Rural Highways ◽  
Speed Flow ◽  
Free Flow Speed ◽  
Flow Diagrams ◽  
Analysis Models

Free flow speed is used as a parameter in transportation planning and capacity analysis models, as well as speed-flow diagrams. Many of these models suggest estimating free flow speed according to measurements from similar highways, which is not a practical method for use in B&H. This paper first discusses problems with using these methodologies in conditions prevailing in B&H and then presents a free flow speed evaluation model developed from a comprehensive field survey conducted on nine homogeneous sections of state and regional roads.

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