As a part of the Plzen's smart city policy, the city representatives came in contact with the OpenTransportNet (OTN) project (EU project co-funded under the ICT-PSP grant agreement no. 620533) with the goal to visualise the traffic model of the city. The large dataset with detailed modelling of traffic volume had only been used by Plzeň's traffic engineers and city planners for urban planning purposes. The usage of the traffic model was restricted for these purposes until it was made available to public as open data in a form of WMS-t within the OTN's traffic volumes application.

At the same time the city asked OTN to calculate how the traffic will change during road works planned for the coming two years. The city currently prepares the launch of the construction works on the two major roads connecting the suburbs with the Plzeň city centre. Large-scale traffic issues are expected when driving down-town due to these works. The city is interested to use the OTN's traffic volume visualisation to communicate the traffic disturbance to its citizens in an interactive way.

OTN team developed the traffic visualisation for Plzeň which allows to compare the normal city traffic with the traffic issues that will occur in coming years. Using the traffic model provided by the city, OTN calculated the changes in traffic volumes for four situations:

• A: Mikulášská street  and B: Karlovarská street
• A and B open (normal traffic)
• A closed, B open
• A open, B narrowed to one lane
• A closed and B narrowed to one lane

Then two traffic visualisation were developed for the city of Plzeň to show the above described traffic flow situations.

PLZEŇ TRAFFIC VOLUMES

http://opentransportnet.eu/web/guest/app-details?id=28

The traffic visualisation is based on the traffic model of the city. It allows users to compare the normal city traffic with three situations that will occur in the coming years. The app displays the traffic volume in one hour intervals and displays the absolute amounts of vehicles per road segment.

PLZEŇ - CHANGE OF TRAFFIC DURING ROAD WORKS http://opentransportnet.eu/web/guest/app-details?id=34

This visualisation builds on the previous one. It displays the relative change of traffic during the roadworks at Mikulášská and Karlovarská streets. Data displays the change of traffic in % compared to normal (=no roadworks) situation (symbols: violet colour = decrease of traffic, orange colour = increase of traffic). The visualisation furthermore highlights segments of roads where the traffic will exceed 85% and 100% of the road capacity (symbol: red and black dots). Same as the first app, it also allows to visualise the change of traffic in one hour intervals during a week.         

THE USE OF THE APP (http://opentransportnet.eu/web/guest/app-details?id=28)

• The normal traffic situation is displayed when opening the app.
• The numbers displayed in each road segment mean the number of vehicles which will pass the segment within one hour interval.
• The traffic layer displayed in the red frame represents the traffic change during road works: The changes in traffic volumes are available for three 'disturbed' situations: these are the 3 layers in the 'S dopravním omezením (other)' box. You can display these layers in the red frame and drag the frame over the 'normal traffic' layer which is displayed at the rest of the map screen.
• The red frame is resizable. By dragging the red box over, you can easily compare normal with the 'disturbed' traffic situation and consult how the traffic jams will change when roads are closed.
• The figures displayed over the street segments mean the amount of vehicles which will pass the segment within one hour interval.
• When opening the layer details, you can use the time slider to consult how the traffic changes over time during a week.
• The use of colours is intuitive - the darker the red is, the heavier the traffic is (from the dark green line which represents the traffic volume lower than 25% of the road capacity up to the dark red which exceeds 100% of the road capacity). Use of Symbols: 'V' stands for the volume of traffic in a road segment, 'C' stands for the capacity of  a road segment.Data is provided as a WMS-t service from the database. The web app is based on the customized HSLayers (HSLayers builds on top of two known JavaScript frameworks, namely OpenLayers & ExtJS.) http://hslayers.org/

Unlike the OpenStreetMap, the OpenTransportMap provides a data model which is topologically correct and compatible with the INSPIRE Transport Network Schema. Moreover, time related traffic volumes can be calculated in an area of interest in the same way as they are already calculated for the pilot sites of OTN.

The city of Plzen considers the OTN's traffic visualization a useful tool to communicate the traffic situation to its citizens. Therefore the city already used the app to announce the expected traffic changes during planned roadworks to the general public and also intends to further collaborate with OTN on commercial basis, namely to: create a yearly traffic prediction based on the sensors from the streets and to calculate the changes of traffic for major road construction works in the years to come.

The solution is extendible to any region. If not provided with a detailed traffic model of a city or region (like in case of Plten), we can use the OpenTransportMap data (http://opentransportmap.info/) to prepare such visualisation of any city or region. Such traffic volume visualisation have been already created within the OTN project for the Liberec region (Czech Republic), Issy-les-Moulineaux (France) and Antwerp (Belgium).

The solution is built on open source projects - HSLayers, OpenTransportMap The data is made available in a standard WMS-t services.

The City of Plzeň together with four OTN partners (IS-practice, University of West Bohemia, EDIP, HSRS) were involved in developing the traffic volumes app. Using the city's traffic model, the traffic engineers from EDIP calculated the expected traffic changes during the planned road works. University of West Bohemia processed the data and transferred it to a database, which was then used by HSRS to create the WMS-t web services and to visualize these in the HSLayers web interface. IS-practice served as the main liaison with the city, collected the city's user requirements, transferred these to the technical team and also beta tested the application in order to improve the user experience.