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Inventory of Lahti’s pedestrian crossings carried out as a geographical information service

Project

Inventory of pedestrian crossings in the City of Lahti

Commission

Inventory of pedestrian crossings and updating needs as a geographical information service

Customer

City of Lahti

Inventory of Lahti’s pedestrian crossings carried out as a geographical information service

Due to the revised Road Traffic Act, the City of Lahti needed an overview of the pedestrian crossing markings and traffic signs at intersections. Sweco’s experts presented the results of the inventory of pedestrian crossings on a GIS-based web map. The service also supports contractors in different management areas.

The City of Lahti has been cooperating with Sweco in traffic planning for a long time. In spring 2021, the city commissioned an inventory of pedestrian crossings in the city centre. This was due to the revised Road Traffic Act that came into force on 1 June 2020, which changed the way in which cycling path extensions are marked in pedestrian crossings. Cycling path extensions require a give way or stop sign at the junction for motorists.

“The revised Road Traffic Act is linked to the city’s operations in many ways, which is why we had to work out how to update the planning material on pedestrian crossings,” says the City of Lahti’s Traffic Engineer Matti Heikkinen. The situation was particularly challenging because the transition period was very short.

Initially, the city planned on compiling PDF maps of the intersections, but there would have been hundreds of them. “That is why we proposed a cheaper and more versatile solution: a GIS-based web map,” says Sweco’s Senior GIS Specialist Lassi Tarri. The initial data used were the traffic sign material commissioned in advance by the City of Lahti, compiled by using computer vision, and aerial images of the traffic signs and markings of the intersections. “Without them, the development of the GIS-based inventory tool would have been much more difficult. After all, GIS solutions always require data.”

Heikkinen believes that Sweco’s experts understood the needs of the city and the contractors very well. “Our cooperation was good and smooth, even though it was not a traditional planning project.”

Geographical information service easy to use and update

Experts developed a process based on computer vision that analyses aerial images to determine whether a marking on a given intersection is a pedestrian crossing or a cycling path extension. The results were compared with the traffic sign material on stop and give way signs at intersections. “This gave us reliable information on whether new traffic signs and markings were needed at the intersection,” Tarri says. The results revealed that more than 1,200 pedestrian crossing markings and almost 4,000 additional panels needed updating.

The map tool is open to everyone and works with a web browser. The map view can be zoomed to a 360 view of a given intersection, allowing the city’s authorities and contractors to see the need for updating as a whole, by management areas or for a specific intersection. In addition, the service was designed to accommodate the constantly changing urban infrastructure. “We gave the City of Lahti editing rights to the service so that they would have the ability to update information about the intersections,” Tarri states.

The use of GIS data has already moved from design to implementation. “In the right hands, the GIS interface is easy to use, and data can be edited during projects,” Heikkinen states.

The development of the geographical information service included an assessment of the costs of the various contract districts by their management areas and building blocks. “Thanks to the accurate cost estimate, the city has been able to plan well in advance for the correction of the markings as investment expenditure,” Heikkinen says. “Achieving the safety objectives of the Road Traffic Act is very important to us, and this is something the geographical information service has been very successful at.”

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