Methods for estimating pedestrian and cycle traffic. Survey and quality assessment

This report is part of the project Measures and methods for evaluating pedestrian and bicycle traffic and summarises the present needs for, and the procedures applied in, estimating the proportion of total travel represented by pedestrian and cycle traffic. The report also comprises an analysis of the data available in Sweden in the form of travel surveys and measurements of pedestrian and cycle traffic flows. In the analysis, different methods are compared, similarities and differences are identified, and the significance of these differences for monitoring pedestrian and cycle travel is discussed. The aim of the project is to propose a harmonised method for estimating the proportion of cycle and pedestrian traffic in Swedish towns.

Most local authorities have some type of target with regard to cycle traffic, while target formulations for pedestrian traffic are less frequent. To increase the proportion of total travel represented by cycle traffic is the most common target. However, this target is seldom followed up, and it is mostly the numbers of cyclists at certain points that are measured instead. Many local authorities make annual flow measurements in order to monitor their overriding targets regarding cycling and to prioritise certain measures among others, or to monitor specific measures on individual routes. Travel surveys are made less frequently and are mainly used in planning and monitoring general plans. In certain cases, local authorities have made additional surveys for their own areas within the framework of regional travel surveys. These can then be used to analyse travel at local level also, inclusive of the journeys in the local authority area by people commuting into the area. In principle, national travel surveys such as RES 2005–2006 could be used for monitoring pedestrian and cycle travel at local level, but as a rule there are far too few observations in individual towns.

The survey and analysis have demonstrated that there are several differences in method between different travel surveys, and that these have distorted the results concerning the choice of mode. Both the method as such with its definitions and limitations, and the quality of the various phases in its implementation, play a part. Our analyses have for example shown that the definition of travel (main trips, part trips, trip element) is of especially great importance. This has consequences in comparisons between different places and also for monitoring over time. The period spent on collecting data and the period for which the results are reported also have an important part to play. RES collects data over the entire year, while the local investigations and measurements often focus on spring/autumn and weekdays.

There are also differences between cycle counts, from fixed measurement points at a few places to manual counts at a relatively large number of places. It is often the cycle flows to/from the centre of the town that are counted. In some cases, short counts are combined with those at some fixed measurement point, and the counts are scaled up into daily or annual values. Many local authorities collect weather data during these measurements, but few correct the traffic data with respect to these. Measurements are mostly made in the spring or autumn. Measurements of pedestrian flows are becoming increasingly common, and are often made by organisations such as "City Interaction" or similar. The arrangement is often based on the way cycle counts are made.

Since travel surveys and traffic flow measurements measure different things, conclusions based on the different sources may at times differ. The measurements may show that people cycle more than ever before, while travel surveys show that the proportion of cycle traffic is decreasing. Both conclusions may be right, and they reflect the importance of the methods employed, and also of the units (numbers or proportion). The unit "proportion" is made up of more components than pedestrian and cycle traffic as such, and depends above all on the total travel. It is therefore not only the proportions that are of interest but, for example, also the number of trips per person.


Keywords

  • Traffic analysis
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  • Walking
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  • Cycling
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  • Traffic count
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  • Journey
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  • Behaviour
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  • Modal split
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  • Data acquisition
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  • Method
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  • Research area: Traffic analysis
  • Published: 2010-09-09
  • VTI-code: R686

VTI rapport 686 (93 pages + 5 Appendices including 34 pages, 1 411 kB, written in Swedish with an English summary)

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