Everyday Mapping of Traffic Conditions - An Urban Planning Tool Laboratory of Geodesy Aristotle University of Thessaloniki, Department of Civil Engineering Prof. P. Savvaidis - Ass. Prof. I. Ifadis - Dr. K. Lakakis

A major problem in designing a traffic plan for an urban area: The availability of traffic data and the cost in time and money of their updating A major problem in designing a traffic plan for an urban area: The availability of traffic data and the cost in time and money of their updating The traffic conditions are characterized or can be simulated by: Mean vehicle speed Traffic volume, traffic density Traffic capacity etc. The traffic conditions are characterized or can be simulated by: Mean vehicle speed Traffic volume, traffic density Traffic capacity etc.

Observations carried out at certain points Movement of a vehicle along traffic routes Use of recording instrumentation Observations carried out at certain points Movement of a vehicle along traffic routes Use of recording instrumentation Traditional ways of obtaining traffic data:

Simple in practice Time consuming Need a large number of observers to cover a road network Provide data only for the period of the measurements Updating the observed data in a future occasion requires the organization of a new survey The results will again soon be out of date Simple in practice Time consuming Need a large number of observers to cover a road network Provide data only for the period of the measurements Updating the observed data in a future occasion requires the organization of a new survey The results will again soon be out of date These conventional techniques are:

A land navigation system was developed in the Laboratory of Geodesy, School of Civil Engineering To overcome these problems: The system was used in a pilot project as the mean for the determination of the basic traffic parameters in the downtown part of the city of Thessaloniki.

Vecon (VEhicle COntrol and Navigation System)Vecon

Continuous GPS Reference Station Controlled Moving Units Telecommunication System (UHF) GIS Unit CONTROL STATION VEHICLES GPS antenna GPS receiver Prime Unit of GPS Differential Corrections GPS antenna GPS receiver RTCM ready Antennas Transceivers Modems Spatial and Time Digital Maps (x,y,t) Regression, Exponential smoothing, Autoregression, Adaptive Filters, etc. Graph Algorithms. Shortest path, Best delivery route, etc. User Interface USER USER (ΝΜΕΑ format) (RTCM format) Vecon Vecon Framework

Continuous GPS Reference Station GIS Unit Vecon Control Station

The Vehicle Unit Vecon Vehicle Unit or Sensor Telecommunication System (UHF) Vecon Control Station

Vecon How Vecon works: When incorporating the system for the first time, the GPS/GIS operations are based on available existing digital maps of the area of interest The system computes and displays a new digital map of the area under investigation with the accuracy of the DGPS Depending on the number of vehicle sensors and their travelling along the urban road network, the system gradually builds its own map in a continuous and self-feeded way When incorporating the system for the first time, the GPS/GIS operations are based on available existing digital maps of the area of interest The system computes and displays a new digital map of the area under investigation with the accuracy of the DGPS Depending on the number of vehicle sensors and their travelling along the urban road network, the system gradually builds its own map in a continuous and self-feeded way

GPS is a very accurate timekeeper with spatial reference The GPS module of the system provides continuous recording of time data The obtained vehicle positions always refer to specific times easily found in the resulting files By using the appropriate software, the time needed for each vehicle sensor to travel between two nodes of the road network can be computed GPS is a very accurate timekeeper with spatial reference The GPS module of the system provides continuous recording of time data The obtained vehicle positions always refer to specific times easily found in the resulting files By using the appropriate software, the time needed for each vehicle sensor to travel between two nodes of the road network can be computed Vecon How Vecon works:

Computation of traffic data: For each segment, the travel time between the starting and the ending node is computed from the GPS time data. Knowing the distance between the nodes and the respective travel time, the speed of the vehicle along the particular road segment is computed. For each segment, the travel time between the starting and the ending node is computed from the GPS time data. Knowing the distance between the nodes and the respective travel time, the speed of the vehicle along the particular road segment is computed.

Traffic volume Q (vehicles/hour) can be related to mean vehicle speed V both theoretically and empirically (e.g. by using the equations proposed by Greenshields or by Greenberg) Traffic density K (vehicles/km or mile) can be also computed from empirical equations giving the value of K as a function of the mean vehicle speed V (e.g. the Greenberg equation) Traffic volume Q (vehicles/hour) can be related to mean vehicle speed V both theoretically and empirically (e.g. by using the equations proposed by Greenshields or by Greenberg) Traffic density K (vehicles/km or mile) can be also computed from empirical equations giving the value of K as a function of the mean vehicle speed V (e.g. the Greenberg equation) Computation of traffic data: Q = 122 V – 1.65 V 2 Q = 227 V e –V/17.2 Q = 122 V – 1.65 V 2 Q = 227 V e –V/17.2 K = 227 e – V K = 227 e – V Q = 74 K – 0.61 K 2

Single Vehicle Sensor Small Fleet of Vehicle Sensors travelling along the road network of an urban area according to a pre-determined plan Vehicle Fleet Systems already operational Urban transportation units – buses Taxi fleets Single Vehicle Sensor Small Fleet of Vehicle Sensors travelling along the road network of an urban area according to a pre-determined plan Vehicle Fleet Systems already operational Urban transportation units – buses Taxi fleets Vecon Possible Vecon Vehicle Sensors:

Urban transportation units will give information along main roads Taxi vehicles will cover the main and secondary roads in a random way Taxi vehicles can very soon gather a lot of data all during the day The time database of the system will be continually enriched, thus updating the available traffic data on an everyday basis Urban transportation units will give information along main roads Taxi vehicles will cover the main and secondary roads in a random way Taxi vehicles can very soon gather a lot of data all during the day The time database of the system will be continually enriched, thus updating the available traffic data on an everyday basis Vecon Possible Vecon Vehicle Sensors:

Vecon The Vecon System: functions as a self-governed closed system because it can produce the needed digital geographical database from its incoming information records travel times with the help of the GPS system for every road segment driven through by each vehicle sensor, thus providing a digital time database from which traffic parameters can be also computed can make use of existing vehicle fleets in an urban area, rapidly collecting data and covering the whole road network in the simplest way can be defined as a dynamic system because, during the everyday operation, it continuously updates and corrects its databases, optimizing in this way their effectiveness can be used for real time monitoring of traffic conditions under disaster or emergency situations when all the previously available data become invalid or unreliable functions as a self-governed closed system because it can produce the needed digital geographical database from its incoming information records travel times with the help of the GPS system for every road segment driven through by each vehicle sensor, thus providing a digital time database from which traffic parameters can be also computed can make use of existing vehicle fleets in an urban area, rapidly collecting data and covering the whole road network in the simplest way can be defined as a dynamic system because, during the everyday operation, it continuously updates and corrects its databases, optimizing in this way their effectiveness can be used for real time monitoring of traffic conditions under disaster or emergency situations when all the previously available data become invalid or unreliable