1. Home
  2. TRID
  3. View Record
https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Definition, parameters and measuring the smooth flow of road traffic

Tieliikenteen toimivuuden maarittely, tunnusluvut ja mittaaminen

Smoothly flowing traffic is part of the service level of road traffic. In this study, the smooth flow of traffic is defined on the basis of journey times and their variation. The factors that impact on the smooth flow of traffic include the degree of connection, the ease of flow and reliability performance. The degree of connection describes the journey time that can be achieved within the speed limits in good conditions without being affected by other traffic; the ease of flow describes the variation in journey times that can mainly be predicted; and reliability performance is the predictability of the variation. Information about the smooth flow of road traffic and its development is needed at various stages in planning road maintenance. The key uses for this information are monitoring the state of the road network and in giving reasons for and prioritising projects. In future, more comprehensive demands relating to the smooth flow of traffic will be incorporated into procurement procedures, and monitoring their implementation will require the systematic measuring of the smooth flow of traffic. The various factors involved in the smooth flow of traffic can be measured separately. Separate measurements will allow a more detailed description of the types of shortcomings in the flow and the focusing of the right type of measures on the problem areas. The degree of connection can be estimated on the basis of information describing the immovable properties of the road that are contained in the road register. Measuring the ease of flow and reliability performance require information on traffic and its fluctuations. The current shortcomings in the smooth flow of traffic in the road network are focused on the ease of flow and reliability performance. In the future, the travel time information service of the Finnish Road Administration will create the best starting point for measuring the smooth flow of traffic on the basis of data collected on traffic, which will be expanded to cover the most important road links in the main road network and the main roads in large urban areas. The service will enable the ease of flow and reliability performance to be measured automatically on the basis of actual journey times. The ease of flow can be measured on the basis of the severity and frequency of delays. The indicator describes how often the road's traffic demand is close to or exceeds capacity, i.e. to a great extent the same things as the traditional parameters describing the road's level of service (e.g. HCM). However, the indicator will enable more detailed monitoring of the development in the ease of flow based on actual measured data and the assessment of more extensive effects of jams on the network. The majority of the road network will remain outside the travel time information service in the future. The ease of flow can be assessed using calculation models, which will enable an evaluation of the smooth flow of traffic based on journey times also for the road network that is not included in the information service. Likewise, the calculation models can be used for predicting the future development in the ease of flow and in evaluating the impacts of projects. It is proposed that reliability performance is measured on the basis of various factors. The variation in journey times during peak traffic hours and the occurrence of long delays will be measured on the basis of data produced by the travel time information service. The variation in journey times in peak hours describes how large a variation in the journey time the road user should allow for in normal rush hour traffic. Long delays measured separately are typically caused by exceptional circumstances. The occurrence of exceptional disruptions can be measured on the basis of data on disruptions collected in the data system of the Traffic Management Centre, alongside data on journey times, which will enable reliability performance to be measured also for the road network remaining outside the travel time information service. The indicators presented can be introduced once the operations of the travel time information service start. However, in the future it will be necessary to reassess the indicators presented on the basis of data collected from a more extensive road network. The material will enable the development of assessment methods for the ease of flow and reliability performance for the road network remaining outside the information service. This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf2/3201088_Tieliikenteen_toimivuuden_maarittely.pdf

Language

  • Finnish

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01104614
  • Record Type: Publication
  • Source Agency: TRL
  • ISBN: 978-952-221-026-5
  • Files: ITRD
  • Created Date: Jul 17 2008 12:50PM