Science topic

# Traffic Flow - Science topic

Explore the latest questions and answers in Traffic Flow, and find Traffic Flow experts.
Questions related to Traffic Flow
• asked a question related to Traffic Flow
Question
Hello everyone,
I want to study on a road stretch of 55 km long. I want to do my analysis based on the segments of 1 km uniform length. Thus a total of 55 segments will be analyzed in the study. But the problem is how the traffic flow of the intersections present in this stretch can be dealt with. Many intersections are coming in this road stretch. How I will take the traffic flow of the segments consisting of intersections? In some road segments, there is intersection width also present. How the traffic flow of intersection width can be incorporated into my study?
Does anyone know how to deal with such a problem? Please share your thought and suggestions. Any kind of reference or paper or suggestion is highly appreciated.
Thanking you.
Such a road (55 km) should be divided not into segments of 1 km length, but into segments from intersection to intersection. If the length of the segment is significantly greater than 1 km, then it can be divided into sub-segments of a shorter length. Then solving the intersections problem is much easier.
• asked a question related to Traffic Flow
Question
Most car-following models were developed on the basis of some theory, observational studies, or a combination of the two. Many researchers have also used machine-learning algorithms such as neural networks and deep-learning for modeling car-following behavior. But machine-learning approaches are sometimes criticized because they are black-box models.
Would you use a neural network / deep-learning car-following model in simulations for investigating crash behavior/emissions / autonomous/connected or general car-following behavior? Please share your opinion. Thanks.
I have some experience with studying and developing ML based car-following models since I asked this question. One thing I notice is that most articles that propose ML/DL car-following models do not compare predicted trajectories with observed trajectories of acceleration, spacing, and jerk. Only a few studies show predicted trajectories of speed only. All of these studies report metrics such as RMSE, R^2, etc.
In my experience, even with small RMSE values, the predicted trajectories are not necessarily similar to the observed trajectories. Believing that a ML-based car-following model is sufficient for use after comparing RMSE only is therefore not a good approach. A detailed comparison between the theory-based and ML-based models is needed. That should include metrics like RMSE but also dynamic time warping (to compare time-series with time lag), and qualitative comparison between predicted trajectories.
Car-following models also need better fitness functions for calibration/training. Times of reaction and magnitude of acceleration are important aspects that are likely ignored in both conventional and ML based training approaches.
• asked a question related to Traffic Flow
Question
Dear colleagues,
Does anyone know if there are any reference values (i.e., thresholds, service levels) for urban planning practices and analysis, considering the following indicators?
1) criminality/criminal occurrences (*)
2) accidents between vehicles and pedestrians
3) average volume of motorized traffic (in urban areas)
Are there international standards, for example, from ISO or another institution? I would appreciate it if anyone could point out a reference source (link to an article, report, or standard) to support the information.
_____________
(*) For crime, I found only the Homicide Rate as a reference indicator (but without thresholds). This indicator seems to me to be extremely limiting since it ignores other types of crimes that are more common and affect more people, such as robberies (with or without weapons) and theft, in addition to neglecting sexual crimes and assaults (also grave) and vandalism (lighter). It seems that focusing only on homicides is reductionist and omits other risks to the population.
I suggest you to have a look at the following, interesting references:
- Global status report on road safety: time for action.
1.Accidents, Traffic - statistics and numerical data. 2.Accidents, Traffic - trends. 3.Wounds and injuries - epidemiology. 4.Safety - statistics and numerical data. 5.Data collection. I.World Health Organization. Dept. of Violence and Injury Prevention.
- TAG UNIT A4.1 - Social Impact Appraisal - GOV.UK
1 Social Impact Appraisal. 2 Accidents Impacts. 3 Physical Activity Impacts. 4 Security Impacts. 5 Severance Impacts. 6 Journey Quality Impacts and etc.
- Crime, Violence, and Development: Trends, Costs, and Policy Options in the Caribbean
A Joint Report by the United Nations Office on Drugs and Crime and the Latin America and the Caribbean Region of the World Bank
- Sustainable Transport Evaluation. Developing Practical Tools for Evaluation in the Context of the CSD Process
UNITED NATIONS DEPARTMENT OF ECONOMIC AND SOCIAL AFFAIRS
Commission on Sustainable Development. Nineteenth Session. 2-13 May 2011
My best regards, Amir Beketov.
• asked a question related to Traffic Flow
Question
I am using a traffic flow simulator and using a simple two lane straight line scenario.
I am sampling the data at fixed sampling. I want to generate multiple trajectories with different values but I am unable to do so. Is there a way on how obtain different position and velocity samples each time the simulation is executed?
I am using SUMO traci
• asked a question related to Traffic Flow
Question
I would like to create dynamically a bottleneck on Aimsum to replicate the consequences of a crash on traffic.
The scheme would be nominal cpacity -> capacity drop -> back to nominal capacity
Is it possible to do it ? If yes how ?
Hi Thibault Charlottin,
In Aimsun do the following steps:
Projects -> New -> Traffic management -> traffic condition.
This will create a new tab under traffic management. Then you can specify the type of incident e.g., lane blockage, closure, speed change etc., with the ability to specify the duration, lane, location, length etc.
Once you provide this specification, go to your scenario (static, dynamic etc. the one you are working on ), and the 5th tab named strategies and conditions will now show you an option to add the incident you created in the previous step. Run the simulation, and it considers your desired effect.
Hope this helps :)
• asked a question related to Traffic Flow
Question
I'm interested in extracting the vehicles' trajectory of each vehicle during my simulation. I'm not sure if there is a way to export each vehicle trajectory (x, y, time-stamp). I'm considering a signalized intersection.
Alceu Dal Bosco Junior , many thanks for you suggestion. Just to add to the discussion below a script to export .fzp file to excel.
# -*- coding: utf-8 -*-
"""
Created on Mon Feb 28 10:33:07 2022
This script export a xlsx file from the .fzp
VISSIM's direct output
See Jupyter Notebook for plot results on :
@author: agustinguerra
"""
from pathlib import Path
import pandas as pd
import os
from datetime import datetime
# get time to save excel data files
now = datetime.now()
current_time = now.strftime("%y%m%d_%H%M%S")
# seek for fzp file and transfor to text
file_name = 'Speed At Signals_001.fzp'
p = Path(file_name)
# save text if no text file in directory
if os.path.exists(file_name):
p.rename(p.with_suffix('.txt'))
# open text file get right lines to read from
file = open("Speed At Signals_001.txt", "r")
file.close()
# write to txt file the data
textfile = open("Speed At Signals_001.txt", "w")
for element in lines_list:
textfile.write(element)
textfile.close()
# read data frame and save it to notebook directory
column_names = ["time", "vehID", "lane", "lane_index", "position", "des_speed", "dist_tsb", "speed", "acc"]
path_to_notebook = os.path.dirname(os.getcwd()) + "\\Notebooks\\"+str(current_time)+".xlsx"

• asked a question related to Traffic Flow
Question
For dealing with traffic complications the authorities do not have a magic wand in their hands. But there is always a possibility of improvement. The suave and proficient implementation for mobility of traffic can be accomplished by making best use of the existing system. The proper sign posts, zebra crossing, footpaths, subways and signals are the tools which can be used to transmute commotion into a smooth and effective mobility. We need to take appropriate traffic management measures after trying out their effects. In order to curb the jeopardy of mishaps caused by the maladministration of traffic we need to contemplate abysmally to this nuisance. Due to obliviousness of the rubrics, rowdiness, desertion and waywardness, the roads are wrenching into muddle. The authorities are wedged in torpidity and have no intimation of how to make traffic more affable. Hardly any zebra crossings are visible in Srinagar city. There are no passable parking facilities. The authorities are decreeing conceitedly that considerable challans are imposed on daily basis. Challans will only result in proliferation of corruption. There should be an obligatory training for the commercial vehicle drivers. Public infringing should be circumvented on the roads, there is need to accentuate the pedestrian crossings. Traffic police need not only check the vehicles but also pedestrian traffic. They should thwart people from crossing roads at high traffic zones. Fine should be levied on the pedestrians who are not using zebra crossings and foot paths provided they exist. Training is a vital contrivance and instructors need to be trained first who should be taught how to train.
It is highly advocated to instil the skills and awareness in the schools and colleges also. It is noticed that the tippers, tata mobiles and other commercial vehicles are driven by minors who do not have any inkling what gaffes they can do on the roads. Rash driving and racing between the commercial vehicles are the causes of accidents. The traffic authorities only know how to do challans, they only punish the drivers who are possessing incomplete documents. They do not prevent the drivers from pledging mistakes on the roads. How many drivers have been penalized for rash driving? Another cause of accidents in Srinagar is teenage bike riders, who are endangering their lives for the sake of stunts that they perform in the cold weather imitating aerobatics. Bikes should have been proscribed in winters in Srinagar a long back, at least for the months of December and January. Another hazard is overloading in commercial vehicles. This has been going on for decades and no one is taking a heed. We have seen passengers boarding and getting down from the commercial vehicles in the middle of the roads. Accidents happen due to the indiscipline created by the commercial vehicle drivers. These drivers know the traffic rules but deliberately break them. In such cases impounding of driver licence for 15 days or 20 days is recommended. The monetary penalty need to be revoked as it only increases corruption. There need to be some firm guidelines for acquiring commercial licence.
The number of vehicles plying on the Srinagar roads has increased to manifold but the roads are the same. So there is a necessity of splaying all the city roads. Foreshortening the density of traffic through hectic plugs is need of the hour, specifically during peak hours. Increasing the number of flyovers and subways will also make the proper traffic flow on the roads. We need to increase the infrastructure facilities for smooth flow of traffic. The train connectivity like metro train should be introduced in the city. One ways should be made the norm throughout. Waterways should be used to conveyance and transport of the goods wherever possible. Traffic police should be deployed at schools and colleges during the peak hours. The commercial drivers need to be educated about their negligence. Shifting of education institutes and government offices to the suburbs is a virtuous alternative.
The basic need is well maintained road and the traffic law obeying drivers on the road!
• asked a question related to Traffic Flow
Question
The boundaries of my investigations limits by real implementation on cities which are too far from driverless cars, ITS or other hyperllops-like decisions. I carefully examined,perhaps, all the existed models and approaches from japanees "Jamology", limitations of transport flows in the centre (of London,tax model), VANET, platooning, V2X, SCATS, SCOOT, traffic lights management and other methods which have some limitations from 'non detected' [without any sensors] vehicles (old cars, mini bus taxies or so-called "root taxy" , horses and carts , motocyclies, scooters, etc. or the bypass roads (which have exits in the centre of calculating zone and make some deviations in algorithms).
Not everything is solved by the development of public transport. In our city, it is planned to build a subway for 20 years, but the zones of the city are developed according to their own laws without taking into account the plans laid down for the metro, and therefore part of the dug canals under the ground do not meet today's needs.
Similarly, with the development of cycling and pedestrian zones. In countries with sharply continental weather in the cold season, it is unlikely that the city dweller will choose a bicycle instead of his personal car while the temperatures below 20 °C. Bus routes can have a certain effect, but again, dedicated lanes are needed (consider adjustments to the law and traffic regulations) and the replacement of a fleet for more comfortable trips as well as more developed routes. Inspection of road regulation(the police) is not as much interested in solving the problems of traffic congestion. The main indicator of the success of their work is the minimum number of accidents and victims on the roads. Therefore, the lower the traffic flow rate or its "standing", the calmer. Thus, what solution can really be implemented in cities where there are no autonomous and flying cars, where the budget is not enough to build monorails and tunnel stations (junctions) to connect metro, buses and other vehicles in rooms with comfortable conditions (for example, Queensland , New Zealand)?
Dear Alexei
Sorry for the delay. The Thesis is in Portuguese, but the results were presented in the 2020 PLEA.
FORTES, M. B. ; GIACAGLIA, M. E. ; DUARTE, Denise . Disruptive Technologies on Mobility Raising New Opportunities for Urban Design. In: PLEA 2020 - Planning Post Carbon Cities, 2020, A Coruña. Proceedings of the 35th International Conference on Passive and Low Energy Architecture. A Coruña: University of A Coruña, 2020. v. 1. p. 600-605.
• asked a question related to Traffic Flow
Question
the traffic light sometimes is easier to cause the traffic jam problem, if the designer don't make to many change to the both side of the road,such as the house and block building, what other aspect of things can be done to mitigate the traffic jam problem.
Dear Dr. Yang Ying ,
I suggest you to have a look at the following, interesting reference:
- Reducing Traffic Congestion and Pollution in Urban Areas
Modern, sophisticated initiatives that are better than typical ‘big ideas’ include:
• Optimise traffic-light management
• Use CCTV to monitor road conditions
• Enforce existing road traffic laws
• Improve perceptions of buses
• Extend residents’ parking zones
• Charge for workplace parking
• Improve cycling infrastructure
• Improve bus services
• Develop and refine park-and-ride
• Use Inbound Flow Control
• Rationalise distribution and deliveries
• Existing rail network
• Light rail
It is often incorrectly suggested that congestion may be solved with one big idea, such as:
• Remove bus lanes
• Build tunnels
• Build a new ring road
• Build a light rail network
• Switch off traffic lights
• Ban cycling
• Ban cars from city centres
• Close through-routes to private vehicles
• Close car parks
• Build more car parks
• Build more park-and-rides
• Make buses free
• Make park-and-ride free
• Introduce a congestion charge/road pricing
- Reducing Traffic Congestion and Pollution in Urban Areas
My best regards, Amir Beketov.
• asked a question related to Traffic Flow
Question
Having available the hourly data on traffic flows in some points of an urban road network, placed heterogeneously and at a great distance from each other (a few tens of kilometers), which software (preferably open) do you recommend to reconstruct the traffic flows on the entire road network?
Thanks everyone for the help
Dear Dr. Marinello!
Based on the webinars (demo) I have seen TIBCO could be an option:
Elise Lakey 2021.Powering the Road to Smart Cities, May 11, 2021, Citation: "smart cities must gather vast amounts of data from multiple data sources including Internet of Things (IoT) devices such as traffic lights and parking sensors when optimizing traffic flows." Copyright © 2021 TIBCO Software Inc., Available at: https://www.tibco.com/blog/2021/05/11/powering-the-road-to-smart-cities/
2) A case-study: Tym Lawrence (2021). Smart Transportation for the Cloud, 25 May 2021, A recorded webinar accessible on-demand via the BrightTALK - platform: https://www.brighttalk.com/webcast/17090/486285
Yours sincerely, Bulcsu Szekely
• asked a question related to Traffic Flow
Question
By collecting traffic flows data in the first 300s in SUMO, I calculated the optimized green time by an algorithm in python and now I want to change the duration of phase in next 300s.But in the documention I did not find useful funtions, so how to achieve this step to complete the real-time control for the traffic lights? Thanks a lot!
Chongqi He, I think this next one works!
In my case, I already have an installed traffic light program (stored as program '0'), then I redefined it with the following code:
phases = []
phases.append(traci.trafficlight.Phase(30, "GGgrrrrrGGgrrrrr", 0, 0))
phases.append(traci.trafficlight.Phase(3, "yyyrrrrryyyrrrrr", 0, 0))
phases.append(traci.trafficlight.Phase(30, "rrrrGGgrrrrrGGgr", 0, 0))
phases.append(traci.trafficlight.Phase(3, "rrrryyyrrrrryyyr", 0, 0))
logic = traci.trafficlight.Logic("0", 0, 0, phases)
traci.trafficlight.setCompleteRedYellowGreenDefinition('B1', logic)
Note: the traffic light ID is 'B1', and I wanted to change the duration of phases 1 and 3 into 30 (initially they were 42).
After printing the new light program, the durations were updated!
• asked a question related to Traffic Flow
Question
Are there any studies done regarding this phenomenon?
There are a couple of studies. See for example:
Huang, Herman F., and Michael J. Cynecki. "Effects of traffic calming measures on pedestrian and motorist behavior." Transportation Research Record 1705.1 (2000): 26-31.
Mao, J., and Glen Koorey. "Investigating and modelling the effects of traffic calming devices." (2010).
Ben-Edigbe, J., and N. Mashros. "Extent of highway capacity loss resulting from road humps." International Journal of Engineering and Technology 4.2 (2012): 121.
• asked a question related to Traffic Flow
Question
Dear researchers,
I'm doing research in Intelligent Transportation Systems (ITS). Currently, we are studying the traffic status, trying to detect any traffic congestion using AI-based solutions. I have used synthetic data (generated by Simulation of Urban MObility) in order to validate our proposed algorithm. However, we are also interested to validate our algorithm in a real-world environment. Can you help me to find a free source for traffic real-dataset?
The data I need should contain:
• Speed, flow, or occupancy parameters on a particular road.
• Labels for the traffic jams (if it's happened), with the starting time of the jam.
Use remote sensing euipments such as drawns with high resolution camera
• asked a question related to Traffic Flow
Question
I am modeling the impact of snow events on traffic flow to extract the relationship between snow events and traffic flow. Known the pattern of the relationship between these 2 variables will be used in the prediction model.
Giving an assumption of snow value, I want to predict the traffic flow value.
I have historical spatiotemporal weather & traffic data, and I was thinking to use trajectories modeling approach to analyze the relationship between these 2 variables in my data.
Then using the trajectory model outcome to train the prediction model in order to predict the traffic flow value.
Not sure if my methodology would achieve my goal or if there's any research work similar to this approach.
I would greatly appreciate it if you share your thoughts.
You may want to consider using STIFF (Spatio Temporal Integrated Forecasting Framework) by using a divide-and-conquer methodology to discover the hidden spatial correlation to obtain the overall integrated forecasting?
Good luck.
• asked a question related to Traffic Flow
Question
I have traffic volume data collected over seven days (morning and evening daily) in 15-min intervals. I want to aggregate this seven-day (15 min counts) data into an hourly volume in order to visualize it through a heat map. Also, how to get AADT, ADT, DHV, and DDHV from this available data? Attached are the TMC sheets (All) in Excel/CSV format for seven days at an intersection (15-min interval counts).
• asked a question related to Traffic Flow
Question
hi everyone, I have developed a simulation of a roundabout with a fixed time regulation, the lines of traffic lights in the roundabout are for vehicle storage. my question is: when we regulate by tricolor light signals, should we make all the conflict zones inactive? and is it normal that we will have vehicles crossing each other? any help will be appreciated, thanks in advance
you can still use conflict areas at a signalised intersection, but should be for movements where the gaps are not determined by the signal lanterns. these might be for particular movements where the headways determine the opportunities (even within a signalised intersection!). otherwise, leave them out.
• asked a question related to Traffic Flow
Question
How Carpooling will reduce Traffic Congestion? I am researching on this in Islamabad.
What will be methodology to find out facts & figure?
Can any one suggest best software or Survey link which would be helpful.
I want to do publication on this topic.
• asked a question related to Traffic Flow
Question
If yes, what car-following/ lane-changing logic does it use?
Recently VISSIM added new tools to model AV through the COM interface. You find training section in "Documents\PTV Vision\PTV Vissim 11\Examples Training\Autonomous Vehicles (AV)" . See also https://www.youtube.com/watch?v=IjwXrN0mQFg&t=1034s&ab_channel=UFTransportation
• asked a question related to Traffic Flow
Question
I have a link with multiple lanes; I want to calculate queue length on each lane at every timestep of a simulation run. I have explored the following options:
1) Makeshift method: creating separate links corresponding to each lane and define vehicle inputs separately. Insert the queue counter on each link. However, it would restrict lane change behavior.
2) Queue counter: It gives the maximum of queue length on individual lanes. I can apply a factor based on the vehicle turning ratio to estimate queue length on each lane.
3) Data collection points: Applying two such points on separate locations on each lane and processing the data from it. But, if vehicles changed lanes in between the two points, then it wouldn't give exact queue length
4) Node evaluation: Not sure how to implement it for each lane. I also suspect it will create an issue the same as the third point.
Let me know if you need any further clarification.
Any suggestions would be much appreciated! Thank you for your time.
Thank you for expatiating on the idea; I got the gist of it. But I am reasonably new to Vissim and not sure about the complexity of implementation. I'll try to apply it and let you know.
• asked a question related to Traffic Flow
Question
What are the methods used to assess the robustness of network with flow? How to model the flow (discrete entities with origin-destination routes) in a network.
Can we say that robustness = size of the largest connected component/size of the network? Apparently we need to see the result of the robustness after several attacks.
• asked a question related to Traffic Flow
Question
I am investigating the influence of PTSD on the road traffic behaviour: as well as micro-reactions of drivers as well as instabilities of the traffic flow. I am working on the question: How to integrate a new driving function (L2 or L3) into a specific driving culture, which also has its traumatizations. So I need to be sure, that this new driving function isn´t triggering any trauma reactions, that could cause disturbances into the traffic flow.
I am inspired by your idea of a truck co-driver, as it could help to coregulate a trauma reaction.
This is an interesting question. I think, if driver's facial micro expressions while driving is tracked using facial recognition software, parallel video monitoring of traffic, along with driver's background (in regards to PTSD, like previous encounters, accidents, etc), vehicle condition, health, weather, could be incorporated into an model. Then it can give you the revelation you are looking for. I am just placing it in a simple manner, however, this entire process involves lot of experiments, tweaking and patience.
• asked a question related to Traffic Flow
Question
Dear colleagues
Hope to be in high spirit and healthy situation
I need any website address which publishes the traffic volume data of main roads in any country for different time periods.
It doesn't differ that belongs to any country.
• asked a question related to Traffic Flow
Question
Hi everyone,
I am doing traffic modeling with VISSIM 10 and the COM interface. I am writing some Python scripts to run VISSIM simulations, implement some scenarios and controls, and collect data. In one step of my code, I need to collect the traffic flow measured by data collection groups and here is what I did:
vs = com.Dispatch("VISSIM.Vissim.1000")
dc = vs.Net.DataCollectionMeasurements.ItemByKey(DataCollectionGroup_ID)
flow = dc.AttValue('Vehs(Current,Max,All)')
The result is always "None" and I got really confused. I pretty much followed the sample code provided by PTV. One possible reason I can think of is that I am running single step simulation but the sample code runs continuous simulation. I run single step because I need to apply something at certain time during the simulation and I prefer not to change it.
Appreciate for any help or suggestions and thank you in advance.
you need to got configurations and highlight all the vehicle classes, then you can see the flow data.
even you can change the interval times
• asked a question related to Traffic Flow
Question
I have 15-minutes traffic volume count data at different locations along a highway stretch. With this data, I want to calculate ADT and AADT.
There are some typical coefficients that could be used to predict AADT from Peak hour volume and vice versa. The general equation is:
DDHV = AADT*K*D where DDHV= directional design hour volume (your 15-minute count times 4 times)
K = proportion of daily traffic occurring during the peak hour
D= proportion of peak hour traffic traveling in the peak direction of flow
There are some recommended values for K and D depending on the type of road (rural, suburban, urban, etc.)
You can check "traffic engineering" book by Roess, Prassas, and McShane for these values.
• asked a question related to Traffic Flow
Question
There are many papers that describe the methodology. But is there any online example that shows all the steps? Or a free program that could be downloaded to use with VISSIM?
No, unfortunately.
• asked a question related to Traffic Flow
Question
Hi,
I have a question about the highway traffic density, based on traffic flow rate (TFR):the number of vehicles passing through a given location per unit time. Based on above, the number of vehicles in (1 km : an example) can called Low/High Traffic Density?
Thank you.
First, you do not specify whether you are looking at signalized locations or general highway lanes.
If at a signalized approach in an urban setting, per AASHTO, the per-lane capacity is between 500 and 700 veh/hr. The typical per-lane capacity of a highway is 2,000-2,200 vpl. Now you can have a basis to determine high vs low demand.
Let’s assume that at 80% of the capacities I cited above is LOS D, then you can do the math that at volumes below the D threshold, you are at low to moderate conditions.
Of course this is simplistic because there is no accounting for local conditions such as the presence of high turning volumes, weaving conditions at closely spaced ramps, lane widths, and the like. But at least you have some sort of threshold to start with.
• asked a question related to Traffic Flow
Question
I am a master student in Brazil and would like to know if it would be possible to share the Matlab files corresponding to this work (Matlab-code for Traffic Flow Comparison of Roundabouts and Crossroads). Thanks a lot.
i think that Santiago is right
• asked a question related to Traffic Flow
Question
I have test vehicle, and i used camera to measure the headway time for the flow, so is it possible to estimate the traffic flow volume using this test vehicle without return in the opposite direction??
You have me curious with your curious question...I couldn’t open the pdf.
• asked a question related to Traffic Flow
Question
I need to find a tool for road traffic modeling which permits the implemention and testing of any type of algorithms for traffic flow prediction, especially neural networks or fuzzy based algorithms. It will be helpful if that tool provides a graphical view of car movement and crossroads configuration.
Simulation of Urban MObility
• asked a question related to Traffic Flow
Question
Smart Cities are the intersection of multiple traffic flows for the transportation of people and freight. How to optimise the throughput of such flows, and keep the city safe and sustainable (for people and for the environment)?
Are there priority schemes, and where is the issue most intense? Is it at main artery level, or in the suburbian capillarity? Is congestion the sole problem to address?
Smart city monitors the conditions of all of infrastructures, transportation facilities, bridges, tunnels, rails, subways, airports, ports, communications, water, power. This helps to better optimize its resources, plan its preventive maintenance activities, and monitor security aspects while maximizing services to its citizens (Hall, R. E. 2000).
• asked a question related to Traffic Flow
Question
I have a project on the impact of speed cameras on traffic flow and road safety performance in urban areas
I would say it depends. Countries where speed enforcement using video camera is common, drivers may slow down. However, developing countries like India where speed enforcement is lagging, we didn’t observe any influence.
• asked a question related to Traffic Flow
Question
Parking in PTV Vissim
Thank you sir for your time. i will follow the steps you mentioned and i hope i'll work
• asked a question related to Traffic Flow
Question
Now I am thinking about the idea of optimizing the traffic flow of cars in the urban road-street network, controlled by autopilot.
I heard that in Hanzhou (and not only), the City Brain 2.0 traffic control system developed by Alibaba was used. Where to find a link to an article describing this system?
The following presentation (Sept. 2018) may be helpful:
Maybe following conference paper as well:
• asked a question related to Traffic Flow
Question
The existing route direction of vehicles ( please check figure in below) in a city has been drawn for a research. Are the number of conflicts at each intersection drawn correctly? Would anyone kindly evaluate the drawing and give any suggestion?
N.B: Please name the intersection as CMM, PMM, KGM, TM, IM
• asked a question related to Traffic Flow
Question
Dear scientists,
Hi. I am working on some dynamic network flow problems with flow-dependent transit times in system-optimal flow patterns (such as the maximum flow problem and the quickest flow problem). The aim is to know how well existing algorithms handle actual network flow problems. To this end, I am in search of realistic benchmark problems. Could you please guide me to access such benchmark problems?
Thank you very much in advance.
Yes, I see. Transaction processing has also a constraint on response time. Optimization then takes more of its canonical form: Your goal "as fast as possible" (this refers to network traversal or RTT) becomes the objective, subject to constraints on benchmark performance which are typically transaction response time and an acceptable range of resource utilization, including link utilization. Actual benchmarks known to me that accomplish such optimization are company-proprietary (I have developed some but under non-disclosure contract). I do not know of very similar standard benchmarks but do have a look at TPC to see how close or how well a TPC standard benchmark would fit your application. I look forward to seeing other respondents who might know actual public-domain sample algorithms.
• asked a question related to Traffic Flow
Question
In my thesis, I used queueing theory, in order to evaluate the traffic conditions of a intersection, which produced waiting time, service time etc for vehicles approaching the intersection from each road. Now, a question arise in my mind that can I use this type of data for Intelligent Transportation Systems (ITS).
interest
• asked a question related to Traffic Flow
Question
Hi, I am working on the simulations of Aw and Rascle second order model for traffic flow, the model does not produce stable results, Why is that so ?
The numerical scheme is stable, i have checked the scheme for other models, it is quite good.
Cześć, Jak można przeprowadzić kalibrację? Czy oceniasz kalibrację używanego schematu numerycznego?
• asked a question related to Traffic Flow
Question
I wanted to know the advantages of data mining techniques are, when compared with macroscopic traffic flow models, microscopic models, simulation models for transportation traffic congestion prediction? Which one has a higher performance data mining techniques like decision tree, SVM or simulation approaches or simple travel time and speed prediction approaches?
There are many advantages of data mining over the macroscopic approaches, In general the macroscopic approaches are less complex and easy to implement. Anyhow, congestion in many traffic scenario can be approximated by by higher order traffic flow models, one can get the realistic characterization of traffic flow using the HOM.
• asked a question related to Traffic Flow
Question
I'm referring Highways England network journey time and traffic flow data to build traffic path recommendations based on time series analysis. Said data set is freely available at link
Wanted to know is there any research paper cited above data set and looking for other similar data sets for building path recommendation model.
Is there any European research journal related to publication of road traffic finding ? Please suggest procedure to publish the work.
• asked a question related to Traffic Flow
Question
I want to apply the shockwave theory to the traffic behaviour at weaving section with an auxiliary lane. What is the appropriate methodology? Is it appropriate to apply the theory of moving bottleneck for such a case? Also is it better to analyse traffic density per lane for the application of shockwave theory given that the weaving section and the upstream traffic has unequal number of lanes?
Dear friends,
what are the most challenges of upstream and downstream shock waves on highways?
best regards,
• asked a question related to Traffic Flow
Question
I do not have access to sources , I need papers on topics like "Is  induced traffic measured by survey ? " and other topics in this regard ! Thanks
have a look may be you will find interesting, its more based on induced traffic through using different urban aspects
and
• asked a question related to Traffic Flow
Question
Hi
I am doing research in evolutionary algorithms in Lane reservation problem. Main task of this work is minimizing negative traffic impact caused by reserving lanes. I have studied more than 8 papers but not a single paper mentioned the negative traffic impact value.
I don't know what is the value of negative traffic impact. Can anyone tell me who have done research in this area?
you need to look at capacity and delay formulations - basic traffic engineering and traffic network modelling , check out Ortuzar & Willumsen (1994,2011) which is the classic text
• asked a question related to Traffic Flow
Question
Dear experts,
Hi. I appreciate any information (ideas, models, algorithms, references, etc.) you can provide to handle the following special problem or the more general problem mentioned in the title.
Consider a directed network G including a source s, a terminal t, and two paths (from s to t) with a common link e^c. Each Link has a capacity c_e and a transit time t_e. This transit time depends on the amount of flow f_e (inflow, load, or outflow) traversing e, that is, t_e = g_e(f_e), where the function g_e determines the relation between t_e and f_e. Moreover, g_e is a positive, non-decreasing function. Hence, how much we have a greater amount of flow in a link, the transit time for this flow will be longer (thus, the speed of the flow will be lower). Notice that, since links may have different capacities, thus, they could have dissimilar functions g_e.
The question is that:
How could we send D units of flow from s to t through these paths in the quickest time?
Notice: A few works have done [D. K. Merchant, et al.; M. Carey; J. E. Aronson; H. S. Mahmassani, et al.; W. B. Powell, et al.; B. Ran, et al.; E Köhler, et al.] relevant to dynamic networks with flow-dependent transit times. Among them, the works done by E Köhler, et al. are more appealing (at least for me) as they introduce models and algorithms based on the network flow theory. Although they have presented good models and algorithms ((2+epsilon)-approximate algorithms) for associated problems, I am looking for better results.
• asked a question related to Traffic Flow
Question
I'm researching driver behaviour on the approach to signals and need more data on how drivers react and adjust their speed under the following conditions:
1)  lead platoon with red signal - no queue at stopline
2) lead platoon with green signal - queue visible and discharging
3) lead platoon with green signal, anticipating onset of red before stop line is reached
I am interested in the variability in reaction time, point of reaction, deceleration rates over 3 stages- @foot off, @brake applied, and @coasting to final stop
This question belongs to 3 years ago but I'd still like to add my comments based on my understandings for the prospective interested readers:
1) For the purpose of your research (and possibly any other aspect of human factors in microscopic level), the accuracy of the data in itself is very important. The NGSIM data is also shown to be riddled with systematic errors due to the rotation of camera and the associated image processing methods. Yet, these errors may not affect your research if you are mainly interested in macroscopic state variables or some aspects of car-following behaviour. But if you are trying to extract additional human factors, these data may not be a good source. the following papers presents more discussion on the accuracy of the NGSIM data:
i) On the assessment of vehicle trajectory data accuracy and application to the Next Generation SIMulation (NGSIM) program data
V Punzo, MT Borzacchiello, B Ciuffo
Transportation Research Part C: Emerging Technologies 19 (6), 1243-1262
ii) Trajectory data reconstruction and simulation-based validation against macroscopic traffic patterns
M Montanino, V Punzo
Transportation Research Part B: Methodological 80, 82-106
2) GPS-based Floating car data (FCD) may not again suit what you're looking as the spatial & temporal accuracy of these data may be below what you may need. Extended floating car data (XFCD), however, can compensate for the limitation of FCD as you have information of the leading vehicle. But this is helpful if at least the temporal resolution of the data is above your human reaction time...
3) If you are developing a new methodology, probably the best way (to my knowledge) is to test it on reconstructed trajecoty data by commercial softwares such as VISSIM & AIMSUN to minimise the effect of systematic error in the process of data collection. You should, however, be advised that whatever results you are getting with using these data are based on Viedemann (VISSIM) and Gipps car-following models (AIMSUN) and may not produce adequate insights about the actual human factors.
• asked a question related to Traffic Flow
Question
The Wiedemann 99 model is applied by VISSIM and it can describe the traffic flow characters of free ways. The details of Wiedemann 99 model are listed in the attachment of this question. The question is how to describe the speed by using acceleration in this model? For example, when a certain vehicle's speed is 90 km/h, is 1.5m/s^2 the acceleration when its need to change its speed? If not, what is the fomulation of the acceleration?
I have been thinking about your question. As we all know, acceleration is the change in speed with respect to time. So an instantaneous speed reading is not enough to know how the vehicle is accelerating, or how it could accelerate. However, we have some hope: suppose we know the maximum speed possible for the vehicle, and some idea of its capability to accelerate. So, a Tesla has really quick acceleration, and could be expected to speed up from 90 to 100 in a very short time. Other vehicles will have other parameters. One model I would use would be to set a max speed, and some rate of change of speed towards that max; then acceleration is the rate of change. If you have an analytical function you can take the derivative. If you have just a graphic, you can do finite differences. As the speed approaches your maximum, the acceleration drops towards zero.
The attached excel sheet has an EXAMPLE -- you would want to modify to place your own model for speed change.
• asked a question related to Traffic Flow
Question
Can anyone give reference procedure or an illustrative example for the estimation of OD Demand matrices through CUBE.
Probably they are estimated through extension CUBE Analyst/Analyst Drive.
Input Data available to me: A prior yearly OD matrix & Traffic Counts (Not Average values)
And lastly, how are the results of output matrix. Are the results reliable and statistically significant?
followed
• asked a question related to Traffic Flow
Question
I have average speeds data for different road section & I would like to build an O/D matrix from it. Firstly, I need to build a relationship of speed & flow to compute flow and then to do OD estimation by using traffic counts (inverse assignment).
If anyone is familiar with the procedure. Please guide
I have never seen a technique to successfully reverse-engineer flows from speeds. I expect that any such data is too noisy to enable you to do so with confidence and I would be very intersted in references to papers that show how and where this was done well.
As for matrix estimation from those reverse-engineered 'counts' - you would usually rely on a half-decent prior matrix of OD flows that you would adjust to the 'counts'. Without such structure the resulting matrix would not be very reliable either.
I think you are setting yourself a pretty difficult task!
• asked a question related to Traffic Flow
Question
Is there actually no recent opensource tool for continuous/macroscopic traffic simulation based on sth. like gas-kinetic-concepts (working on networks deduced from real world maps)?
Thanks
• asked a question related to Traffic Flow
Question
I know that the update time step is equal to the reaction time in many papers using Gipps car following model. I also read the paper by Kesting A. and Treiber M. (2008) and know that they can be different. But I do not know how to update the position of every vehicle when update time is different from reaction time.
If they are the same,
v_n(t+\tau) = F[v_n(t), x_n(t), x_{n-1}(t), v_{n-1}(t)]; % F denotes the gipps car following law
x_n(t+\tau) = x_n(t) + 0.5*(v_n(t+\tau) + v_n(t))*\tau.
\tau denotes the reaction time.
If they are different,
v_n(t+dt) = F(v_n(t+dt-\tau), x_n(t+dt-\tau), x_{n-1}(t+dt-\tau), v_{n-1}(t+dt-\tau));
x_n(t+dt) = x_n(t) + 0.5*(v_n(t+dt) + v_n(t))*dt
Is this right?
yes, you can update like this. But you have to set some initial data to ensure the beginning of the CF models. and i think the tau should be equal to n * dt(n is positive integer ) to ensure the correctness of iterations.
• asked a question related to Traffic Flow
Question
TIA comes with the legal background. Therefore it has been allowed normalize traffic level for all. But there are significant road segments that cannot allow the legal level.
If there any article journals related this please let me know. I like to make a framework for my study. therefore I need the base that other localities use.
Thank you,
Dilshan
• asked a question related to Traffic Flow
Question
I want to simulate the traffic flow of the existing commuter trains and proposed monorail system in city within the other modes of transportation (Street Network).
you can use matlab to simulate moving trains and cars to verify your solutions.
• asked a question related to Traffic Flow
Question
There is a broad spectrum of researches conducted on string stability of platoons. However, to me myself it is not quite clear why do we need to stick on that.
let us assume we have a simple predecessor following model which has been proved to be string unstable. Isn't it possible to produce forward waves in the traffic flow to compensate backward waves?
I believe It is possible to do so by using centralized controllers.
Thank you John for your comment!
My question may need some clarifications.
Let me start with this introduction that, In my opinion when we use the term "platooning" it automatically includes those "platooning strategies" that reduce costs without safety issues. Otherwise, "do nothing" is better than "platooning".
So-called "string stability" concept introduced in the literature is somewhat known (at least as far as I understood) as a criterion for such platooning strategy to avoid cost increase and safety issues. My question in fact target this concept. Thus the question is "Do we really need controllers for platooning to be string stable?" or equivalently " Can string unstable platooning control method still be efficient in the way of reducing costs and safety issues?"
Regarding your follow up question, I should add this point that the question is related to another concept namely "traffic flow stability". In traffic studies, the latter term is usually investigated after "string stability". In other words, exponentially string stable platoons may or may not lead to stable traffic flow.
• asked a question related to Traffic Flow
Question
Usually Time headway is calculated as the time difference between two vehicles (front-front bumper of rear-rear bumpers) on the same position (same lane). in non lane based traffic it is the same but the position is a line on a road stretch (the same direction). what are the motivations behind using the whole road stretch ? In my case I have a road of 3 lanes (same direction) and I group two lanes to see the pattern of time headway. Meaning I calculate Time Headway based on a line along the two lanes. Does this make sense in traffic theory ? It does seem unconventional but since I have vehicle arrival with no respect to lane separators, it seems to me that the arrival of a vehicle in a position on the two grouped lanes is influenced by the preceeding vehicles no matter what it's position in the two grouped lanes.
P.S : Each lane in my scenario is of 3 to 3.25 meters width
In this case (last ten years), the headway in group of lanes during off peak had been provided within 5 seconds. If a driver drove his car passing the virtual loop, it leased to extend the range of green times. Howeve, it was not over the maximum green times. In case of red times, there was no vehicle to pass the virtual loop.
• asked a question related to Traffic Flow
Question
This control technique is considered to be very effective in the field of surveillance.
The PCA or PCANL for non-linear parameters is considered as a tool for avoiding or reducing any anomalies that may occur in the field of system reliability.
• asked a question related to Traffic Flow
Question
Is anybody have the Matlab source code for simulating the traffic flow using Cellular Automata?
• asked a question related to Traffic Flow
Question
Does anyone know of any paper or research work related to the efectiveness of reducing the road wide within urban areas with the purpose of reducing speed and increasing safety? Thank you!
You can explore the attached paper
• asked a question related to Traffic Flow
Question
Hi,
I am working on creating a random road traffic generator, so far i've seen so many random traffic generators either on commercial software or open source software, but i can't seem to figure out how random is it? is there a control on how the arrival generation is done in order to show some phenomenon, like periodicity.
In my case I am working on generating traffic coming from a signalized intersection. while using a distribution with parameters fitted using real data, by generating random Time Headway between vehicles i can't see the periodicity, however when i add a control on how much vehicles should be generated in each period (let's call it the phase in the preceding intersection) using a poisson distribution and after that making sure to not generated Time Headways that would not be more than then the period duration and also not respecting the amount of vehicles generated in a period for computation efficiency (in order to not have the computer do too much loops and take more time in the traffic generation) I can clearly see the periodicity phenomenon. But scientifically speaking is this not interfering with the random generation and adding a bias to my generated data ?
Assume Poisson's arrivals at intersections and incorporate a suitable  headway distribution. The distributions can be deterministic as discussed in Dr. Webster's comments above.
Thanks,
Dr. Bazlamit
• asked a question related to Traffic Flow
Question
In occupancy vs. speed graphs for different modes (cars, motorbikes and rickshaws), the R-squared values were quite low (22.7% to 47.7%), although a clear correlation can be seen.
As car-following is an extension of human behavior, which itself is highly random, low R-squared values were expected. What are some studies that can help me justify these low values? What are ideal ranges for such values in studies in car-following and human behavior in transportation? And if I were to remove outliers to improve the values, how many can I remove?
An Alternative Regression Model of Speed-Occupancy Relation
at the Congested Flow Level
• asked a question related to Traffic Flow
Question
I am looing for a tool for simulating multi-regions (geographical network)? for instance: simulating network topology among different data centers in different regions (London, Seoul, Texas, Boston..) each node in topology could be a region-data centers and user nodes. They are connected each other. The following factor are consider: latency, distance among regions and traffic load. I am trying to simulate to get actual latency/respone time when we generate a traffic flow and it traverses from user to selected region node with given path. In additional, I would like to set and monitoring available bandwidth on each link in that topology as well.  Please help to give me advices in this case. Thank you all
Chik opnet simulator
• asked a question related to Traffic Flow
Question
• asked a question related to Traffic Flow
Question
Is it viable to calculate the pollution only near bus terminals and across the red light crossings and on the basis of that predict the pollution of the whole city?
Pawan,
It appears you have moved the conversation from measuring from a sampling of locations where emissions occur, to one of finding ways to control or solve the pollution problem.
If prevention measures are what you are looking to answer, there are technical as well as human behavioural aspects to the research question. The technical may involve looking at engine technologies, maintenance regimes, and fuels. Behaviourial aspects could involve simple things such as turning the vehicle engines off when the vehicle is on stand by, etc.
Regards,
Ricardo
• asked a question related to Traffic Flow
Question
to study the lack of parking spaces in tehran,I needed to find out how many cars commute in this city to compare to the current parking spaces.
Hi,
You may find these articles useful:
Iran ranked 13th in world passenger cars sales of 2015 - Tehran Times
Apr 2, 2016 - TEHRAN- Iran ranked 13th in the world sales of passenger cars, hitting ... .According to the report, the amount of passenger cars sold in Iran in ...
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Car ownership
Car ownership per household in Tehran. The increasing number of private automobiles in Tehran has turned into a major problem for this metropolis. Tehran, in ...
• asked a question related to Traffic Flow
Question
see above
4 steps model is usually used all over the country. it is easy to use but this model has some disadvantage too.  for this model, we need data for 2% of total population. so that it is too costly in higher population country. there are some model also but those are not easy for their algorithm.
• asked a question related to Traffic Flow
Question
Hi There,
Is there a method or standard to estimate the daily traffic distribution from the peak AM and PM?
Thanks
Dear Arash:
Expanding short counts (less than 24 hours) to ADT can be done using hourly, daily and monthly expansion factors. These factors normally take seasonal changes into account. Search for articles in the area of traffic forecasting and seasonal adjustments. That should help
• asked a question related to Traffic Flow
Question
For example, if a vehicle is performing lateral movement, is it possible to calculate the maximum lateral velocity (maximum lateral maneuvering speed) with which the vehicle can shift laterally.
Hi Punith,
Yes, it is perfectly feasible to calculate the maximum manoeuvring speed of any vehicle. There are several systems simulation tools, mostly based on 'Modelica' which can do the job. Formula 1 racing teams do not fabricate prototypes to test the components (incl tyres) for optimum race trajectory, adapted to each circuit. They simulate the complete chassis and parts, and fabricate the parts with which they will go into the race. Which demonstrates how accurate they believe the results are ; )
All the Best,
Georgi
• asked a question related to Traffic Flow
Question
minimum traffic flow on the road
delay, LOS, accident
Hi Ramesh
Better to read traffic engineering handbook by Institute of Transportation Engineers. If the lane volume is 2000 vehicles per hour or 15,000 vehicles per day or the interestion with very high volume of  pedestrian traffic etc. then interchange is needed. First the existing lane volumes of each lane at the T-intersection should be counted. Then forecast volume after 30 years need to be worked out. A intersection traffic analysis can be carried out using SIDRA or similar software. From the analysis, the layout needed can be worked out for the forecast volume. Usually, maximum traffic signal cycle time is 150 seconds. From the analysis, it is possible to find out at-grade intersection will work or not for the forecast volume. Modelling interchanges can be done using microsimulation models such as PARAMICS, VISSUM, AIMSUN etc.
Best regards
Ravi
• asked a question related to Traffic Flow
Question
I want to evaluate the effects of the differential speed limit (DSL) on driver behavior and speed characteristics in Passing lane on two-lane two-way highways.  I have  data for before condition, which is data for uniform speed limit (USL) in both the lanes of passing-lane section, and also data for after condition which is data for DSL (left and right lane has different speed limits) condition. I want to compare the data for before and after DSL implementation. Now please recommend me a best statistical technique which I can use to get good results.
• asked a question related to Traffic Flow
Question
I've not expertise on traffic flow assessment, but I need a simple model to calculate the amount of traffic on road stretches connecting several nodes, possibly by using only data on population of each town (also through specific transfer functions). The final aim is ranking each road stretch according to the normalized values (from 0 to 1) of amount of traffic.
Hi Roberta,
If you want a simple model to calculate traffic volume on road segments connecting several towns and you have only the population data, you can use the Gravity model. It is not a precise model (aggregate model) and does not take into account key variables. However, it is based on the premise that as the population between two nodes increases so does the traffic flow between them. The distance between nodes is another factor. I think you might look at the Four-Step traffic assignment process (trip generation, trip distribution, modal choice and finally route choice (trip assignment).
• asked a question related to Traffic Flow
Question
I am trying to develop a overtaking behavior micro-simulation  model for non lane based heterogeneous traffic environment using VISSIM to define the number and nature of conflict. I am planing to use COM interface. How can I proceed from the very beginning and what type data need to be collected? Any manual or tutorial is appreciated (if available).
I wonder if you really mean non-lane based mixed traffic. Without lanes and if bigger vehicles (trucks) occupy more lateral space than smaller vehicles (particularly motorcycles and the like), the notion of lane changing becomes meaningless. Instead, it is replaced by a continuous lateral motion  with the objective of passing at a later time. This means, rather than using a car-following and associated  lane-changing model, one has a fully two-dimensional dynamic model. Notice that the ynamics of this situation iressembles more unidirectional pedestrian flow rather than classical lane-based vehicular traffic.
• asked a question related to Traffic Flow
Question
I want to simulate the several traffic models and evaluate their performances in terms of UE throughput.
I have gone through many literature's but ended up on their theoretical aspects only.
Are there any links or journals or textbooks available that deals with their theory and the associated equations?
• asked a question related to Traffic Flow
Question
Hello, I need a model to simulate the formation of traffic jams, to estimate waiting times at crossings, information in this regard. I need to work with a road network on the scale of a medium-sized city (200-500 thousand inhabitants). I have traffic flow data on major roads to feed the system.
Hope someone can help me choose a software.
For traffic simulation there are  free resources demo software are available like ...
• asked a question related to Traffic Flow
Question
I am studying the dynamics of the Origin / Destination data. Currently I have access to flight data but need more public data sets ( e.g. mobile phone usage, car traffic, train, bus, etc. ) for further experiments. Any ideas?
I think you can find accurent data for test  in this website: http://www.bgu.ac.il/~bargera/tntp/
• asked a question related to Traffic Flow
Question
without simulation of WSN  where does the WSN network traffic data set is available-any govt sector or online.for congestion analysis .
Thank u sir.can u please share the details.
• asked a question related to Traffic Flow
Question