MetropAccess-Digiroad is a street network dataset of Helsinki Region, which is modified by taking account intersection movement delays to represent more realistic travel times made by private car (more details below). Modified MetropAccess-Digiroad network dataset is available for two years:
Calculations in both datasets are based on the National road and street database Digiroad (Finnish Transport Agency) and Floating car measurements in the Helsinki Region (Helsinki City Planning Department and Helsinki Region Transport).
Travel time is a typical measure of accessibility which is often measured from the viewpoint of private car users. Many GIS-softwares provide analytical tools for modelling travel times based on road network datasets. Usually travel time calculations are, however, based on only information about speed limits and length of the street elements.
Taking into account only the speed limit of the road network leads to underestimation of drive times especially in the urban networks where the congestion, intersections and parking slow down the traffic significantly especially during the rush hours. Because of this the estimates based on speed limits are rarely comparable to public transport or walking time calculations. Comparing travel times between private car and public transport, we need to take into account the whole travel chain: walking to your car, driving time, parking time and walking to the final destination. Without taking into account these different steps of the journey it is not possible to compare private car and public transport very realistically.
Since the year 2004 there has been maintained a national street database called (Digiroad) which can be used for route optimization and network analyses in Finland. In MetropAccess project we have developed methods and tools to modify this network dataset.
In practice our method creates intersection movement delays that takes into account not only the speed limit but also the effect of intersections and diurnal variation in traffic volumes as decelerating factors. Delays are associated to each road network element separately and the amount of delay varies based on road classes (highway, avenue, street etc.). MetropAccess-Digiroad network dataset is a ready-made street dataset in which the intersection movement delays have been taking into account based on the method that we have developed. Dataset is free and openly accessible for everyone to download.
More details on the method can be found from the Master’s Thesis of Timo Jaakkola (in Finnish only) and in our data description article (full text only in Finnish) (see references at the bottom of this page).
Intersection delays associated to each road class are based on floating car data (FCD) that was collected by Helsinki City Planning Department and Helsinki Region Transport. FCD was used to calculate intersection delays for each road class with linear regression analysis based on the amount of deceleration of intersection to the free-flow speed.
Dataset has been classified into three classes based on time of day: The whole day average (Kokopva_aa) represents the movement delays between 07:00-17:00, the midday (Keskpva_aa) between 09:00-15:00, and rush-hour (Ruuhka_aa) between 07:00-09:00 and 15:00-17:00.
See intersection delays for different road classes (in Finnish: Tieluokka) at different times of the day from this table.
If you use MetropAccess-Digiroad dataset or related tools in your work, we encourage you to cite properly to our work. Description of the MetropAccess-Digiroad tool is included in the following works:
Toivonen, T., M. Salonen, H. Tenkanen, P. Saarsalmi, T. Jaakkola & J. Järvi (2014). Joukkoliikenteellä, autolla ja kävellen: Avoin saavutettavuusaineisto pääkaupunkiseudulla. Terra 126: 3, 127-136.
Jaakkola, T. (2013). GIS-based method for modeling drive and travel times – example of the Helsinki Metropolitan Area. Master’s Thesis. University of Helsinki. The Department of Geosciences and Geography.
MetropAccess-Digiroad by MetropAccess-project/ Accessibility Research Group (University of Helsinki) is licensed under a Creative Commons Attribution 4.0 International License.
More information about license: http://creativecommons.org/licenses/by/4.0/
The data may be used freely. We do not take any responsibility for any mistakes, errors or other deficiencies in the data.