2010
Vehicle Kilometres Travelled in Calgary
Proposed Methodology
The City of Calgary
Transportation Planning
June 2010
2
Table of Contents
1.0
Summary .................................................................................................................................... 7
2.0 Background ..................................................................................................................................... 8
3.0 Methodology Objective and Definitions ..................................................................................... 10
3.1 Possible Methods of Calculating VKT............................................................................................ 10
3.2 Daily Vehicle Kilometres Travelled Definition ............................................................................... 11
3.2.1 Primary Roadway Definitions ................................................................................................ 11
3.3 Data Sources................................................................................................................................ 14
3.3.1 Roadway Segment Lengths Data Sources .............................................................................. 14
3.3.2 Traffic Volume Data Sources ................................................................................................. 16
3.3.3 Traffic Volume Data Source for Primary Roadways with less than 10,000 Vehicles per Day.... 18
3.4 Daily VKT Calculation and Analysis ............................................................................................... 18
3.4.1 Comparison with the Regional Transportation Model Results................................................ 21
3.5 Annual Vehicle Kilometres Travelled Definition ............................................................................ 22
3.5.1 Daily-to-Annual Factor .......................................................................................................... 22
3.5.2 Total Annual VKT per Capita Calculation ................................................................................ 23
4.0 Conclusion and Recommendations ............................................................................................. 26
Appendix A – Statistical Analysis of Recommended Volumes on Primary Roadways with Traffic
Volumes under 10,000 vehicles per day ........................................................................................... 28
Appendix B – Permanent Traffic Counting Station Locations .......................................................... 34
Appendix C – Daily-to-Annual Factors ............................................................................................... 35
Appendix D – Average Fuel Prices in Calgary .................................................................................... 36
References ........................................................................................................................................... 37
3
List of Figures
Figure 1. Calgary Transportation Plan 2009: Road and Street Network................................................... 13
Figure 2. 2008 Flow Map Primary Roadway Network ............................................................................. 14
Figure 3. 2008 Major Streets Missing Links ............................................................................................ 14
Figure 4. Double line example from the RoadNet GIS (red line) replaced with a single blue line in the
Flow Map database ............................................................................................................................... 15
Figure 5. 2008 Flow Map Average 24-hour Weekday Traffic Volumes .................................................... 17
Figure 6. Daily VKT by Roadway Classification ........................................................................................ 20
Figure 7. Roadway Classification Breakdown ......................................................................................... 21
Figure 8. RTM Primary Roadway Network.............................................................................................. 22
Figure 9. Annual VKT in Calgary ............................................................................................................. 24
Figure 10. Annual Vehicle Kilometres Travelled per Capita..................................................................... 24
Figure 11. Population and VKT percentage growth in Calgary since 2005 ............................................... 25
Figure 12. Recommended Value for Skeletal Roads with Traffic Volume under 10,000 Vehicles per Day 29
Figure 13. Recommended Traffic Volume for Major Streets ................................................................... 31
Figure 14. 2009 Permanent Traffic Count Station Locations ................................................................... 34
Figure 15. Fuel prices in Calgary since 2005 ........................................................................................... 36
4
List of Tables
Table 1. Annual vehicle kilometres travelled per Capita for Calgary as reported by Kenworthy ................ 9
Table 2. Recommended Traffic Volumes for Primary Roadways ............................................................. 18
Table 3. 2005 Daily VKT Calculation ....................................................................................................... 18
Table 4. 2006 Daily VKT Calculation ....................................................................................................... 19
Table 5. 2007 Daily VKT Calculation ....................................................................................................... 19
Table 6. 2008 Daily VKT Calculation ....................................................................................................... 19
Table 7. 2009 Daily VKT Calculation ....................................................................................................... 19
Table 8. 2006 RTM Daily Vehicle Kilometres Travelled ........................................................................... 21
Table 9. Daily-to-Annual Factor.............................................................................................................. 23
Table 10. Annual Vehicle Kilometres Travelled per Capita ...................................................................... 23
Table 11. Average Traffic Volumes for Primary Roadways with Traffic Volumes under 10,000 Vehicles per
Day........................................................................................................................................................ 28
Table 12. Skeletal Roads Average Traffic Volume and Sample Size per Year ........................................... 28
Table 13. Skeletal Roads Recommended Volume Analysis ..................................................................... 30
Table 14. Major Streets Average Traffic Volume and Sample Size per Year ............................................ 30
Table 15. Major Streets Recommended Volume Analysis....................................................................... 32
Table 16. Daily VKT Calculation using (µ±S) Traffic Volume Variations.................................................... 32
Table 17. Major Streets Traffic Volume Sensitivity Analysis.................................................................... 33
Table 18. Daily-to-Annual Factor Calculation.......................................................................................... 35
5
6
1.0 Summary
The City of Calgary (Transportation Planning, Transportation Data division) has developed a
methodology regarding the calculation of vehicle kilometres travelled (VKT) within Calgary’s city limits
based on observed traffic volumes. Currently, VKT estimates can be determined from several sources,
including:
•
•
•
•
traffic counts;
transportation models;
surveys;
odometer readings.
It is important to develop a methodology that can be standardized, is consistent and easy to use
nationwide. Estimated VKT (using different sources and/or methodologies) have been used for
comparison with other cities or for benchmarking, which can be misleading if a standardized
methodology is not used.
It is essential to provide a VKT definition with any VKT release, so a number of questions are answered:
Which roadways are taken into consideration in terms of roadway classification? Are they private roads
or are they owned by the municipal, provincial or federal government? Are they within the city limits?
Are average annual daily traffic (AADT) volumes used for the VKT calculation? Are daily or annual VKT
estimates being compared? How is the annual VKT estimated?
This report will attempt to answer some of these questions, as well as propose a methodology that may
be easily adopted by other municipalities. The report will not discuss the factors influencing the VKT
value such as:
•
•
•
•
•
•
spatial segregation of land uses and consequently trip length;
personal income;
auto ownership;
travel time budget;
fuel prices and fuel economy of vehicles ;
Travel Demand Measures like telecommuting and flex work time.
7
2.0 Background
The vehicle kilometres travelled (VKT) indicator is one of the performance indicators that is widely used
in literature as a common measure of roadway use. It is used in estimating congestion and can provide a
general measure of the level of economic activity in a city. In addition, this indicator is used for
transportation greenhouse gas (GHG) emissions and air quality calculations. Approximately 30 per cent
of all GHG emissions in Calgary are produced by transportation sector1.
The VKT indicator reflects the link between land use and transportation. Land uses (home, job, school,
day care, retail, etc.) that are further away from each other result in longer trip lengths and inevitably
lead to more traffic on the streets and more vehicle kilometres travelled2.
The Municipal Development Plan (MDP)3 and the Calgary Transportation Plan (CTP) 4 were adopted by
Calgary’s City Council on September 28, 2009. The Transportation Monitoring and Reporting Program is
being developed to provide a mechanism through which CTP and MDP goals, objectives and policies are
assessed. The progress of achieving these goals, objectives and policies will be reported based on the
measurements of indicators that are identified through the mentioned plans, as well as the Plan It
Calgary Implementation Plan. However, any one indicator should not be taken in isolation of other
indicators, as only a full set of indicators can provide a comprehensive picture in order to make strategic
decisions.
The Transportation Research Board’s Sustainable Transportation Indicators Subcommittee5 identifies
the annual vehicle kilometres travelled (annual VKT) indicator as one of the most important economic
indicators. It is also in direct correlation with environmental indicators, such as greenhouse gas
emissions and air quality.
The Transportation Association of Canada (TAC)6 conducts a survey on urban transportation indicators
every five years. One of those indicators is daily vehicle kilometres travelled by passenger vehicles per
capita. Only a few of the surveyed cities reported the values on this indicator, perhaps because it is
challenging to report on daily VKT for passenger vehicles only without doing an extensive and therefore
1
Plan It Calgary. Where do we grow from here? Workbook, 2007
<http://www.calgary.ca/docgallery/BU/planning/pdf/plan_it/plan_it_workbook_final.pdf.>
2
Reid Ewing, Keith Bartholomew, Steve Winkelman, Jerry Walters and Geoffrey Anderson. “Urban Development and Climate
Change”. Journal of Urbanism, November 2008
<http://www.informaworld.com/smpp/128263918646668579/content~db=all?content=10.1080/17549170802529316>
3
City of Calgary. Municipal Development Plan, 2009 <http://www.calgary.ca/mdp>
4
City of Calgary. Calgary Transportation Plan, 2009 <http://www.calgary.ca/ctp>
5
Sustainable Transportation Indicators Subcommittee of the Transportation Research Board (ADD40 [1]). Sustainable
transportation Indicators: A Recommended Research Program For Developing Sustainable Transportation Indicators and Data.
November 2008 <http://www.vtpi.org/sustain/sti.pdf>
6
IBI Group, Transportation Association of Canada. TAC Urban Transportation Indicators – Fourth Survey. Draft Final Report.
November 2009
8
expensive survey or using a transportation model. Furthermore, those reported values may come from
different sources (e.g., travel demand model or observed traffic count data) and the conclusions could
be deceiving if those reported values are compared between cities that used different methodologies.
For comparison purposes, it is essential to have a consistent and standardized methodology.
The analysis of vehicle miles travelled (VMT) and its trends have been done on a regular basis in the
U.S.7 The Federal Highway Administration (FHWA)8 publishes highway statistics, which contains the
sectional lengths for all public roads and vehicle miles travelled by state. Based on state-managed
permanent traffic counters, the average annual daily traffic (AADT) is measured and then multiplied by
the length of the roadway section to get daily VMT. The VMT for the entire year are calculated by
multiplying daily VMT by 365 (days). The methodology used to calculate VMT is similar to the proposed
VKT methodology in Calgary.
Annual VKT per capita for Calgary was first published in “The International Source Book of Automobile
Dependence in Cities, 1960 – 1990” by Kenworthy and Laube9. It is assumed that the estimates were
provided by The City of Calgary, but the original calculations could not be obtained. The values for this
indicator are given in the table below. Dr. Kenworthy provided a value for 1996 via email.
Table 1. Annual vehicle kilometres travelled per Capita for Calgary as reported by Kenworthy
Year
1971
1981
1991
1996
Annual VKT per capita
4,253
7,057
9,201
8,237
7
Robert Puentes, Adie Tomer. “The Road…Less Traveled: An Analysis of Vehicle Miles Traveled”. Brookings Institution.
Metropolitan Infrastructure Initiative Number 4. December 2008
<http://www.brookings.edu/reports/2008/1216_transportation_tomer_puentes.aspx>
8
U.S. Department of Transportation. Federal Highway Administration. Policy Information. Travel Monitoring.
<http://www.fhwa.dot.gov/ohim/tvtw/tvtpage.cfm>
9
Jeffrey Kenworthy, Felix Laube. “The International Source Book of Automobile Dependence in Cities, 1960 – 1990”. University
of Colorado Press, 1999
9
3.0 Methodology Objective and Definitions
The objective was to develop a process that measures travel demand over time on an annual basis. The
method used to calculate the annual VKT within Calgary’s city limits based on readily available, observed
data should be:
•
•
•
•
•
•
•
repeatable from year to year using available data;
simple and easy to understand;
data are cost-effective to collect;
data are easily and reliably measurable;
VKT estimates are comparable to estimates reported by other cities (assuming the same
methodology is used);
estimates should not vary radically from year to year due to sampling error; and,
allow for future enhancements to improve the quality of the estimates.
3.1 Possible Methods of Calculating VKT
The Regional Transportation Model10 (developed by the Forecasting Division in Transportation Planning)
can calculate daily VKT and forecast future years based on the land use and transportation network
assumptions. As the model is calibrated using the Household Activity Survey, which is conducted every
ten years, and recalibrated using ground counts at five year intervals between surveys, the VKT
produced cannot be used for monitoring on an annual basis.
Currently Alberta has a voluntary odometer reading program. Every year when a vehicle is registered,
one can voluntarily report the odometer reading for that vehicle. In some European countries, odometer
reporting is mandatory. In the long-term, the Province of Alberta might request mandatory odometer
reporting. However, there are a few caveats with mandatory odometer reporting, as it includes all travel
in the city and outside the city (e.g., vacation). Furthermore, there are many company headquarters in
Calgary, so for example, a vehicle could be registered in Calgary, but its location is really in Fort
McMurray and all VKT could occur in and around Fort McMurray. Therefore, using odometer readings to
determine vehicle kilometres travelled in Calgary would not be accurate.
Household activity surveys can be used to determine the number of vehicle kilometres travelled per
household. However, in order to obtain a sample size large enough to obtain an accurate estimate of
VKT many households need to be surveyed and the study becomes extremely expensive. This would not
be practical methodology for reporting on a frequent basis.
10
City of Calgary. Transportation Planning. Forecasting division.
10
3.2 Daily Vehicle Kilometres Travelled Definition
Daily vehicle kilometres travelled are calculated by multiplying the observed 24-hour average
annual weekday traffic volumes by the single centre-line length of the primary roadways
within city limits only.
As part of the definition further clarification is needed:
•
•
•
Daily VKT include all weekday travel on Calgary streets by not only Calgarians but also all visitors
and commuters from the region. It also includes all commercial travel (passengers and goods) on
Calgary roadways.
Daily VKT do not include any traffic volumes on the roadways outside of Calgary (e.g., a trip from
Airdrie to downtown Calgary would only include the kilometres travelled within the city) nor
weekend travel.
All primary roadways were included in the calculation regardless of the ownership (e.g., Deerfoot
Trail is included in the VKT calculation even though it is owned by the Province of Alberta).
It is important to note that the VKT calculation does not include travel on all Calgary roadways.
Residential Streets are not used in the VKT calculation because of traffic volume variations throughout
the city on these roadways. In addition, the existing traffic count sample on these roadways is too small
to make a reliable estimate. Traffic volumes on these roadways could be biased, as the few traffic counts
on residential roadways are usually done as part of traffic calming studies, crosswalk warrants or other
special studies. Furthermore, in the TAC Urban Transportation Indicators, roadway use was measured
on arterials and expressways (or multi-lane highways) only.
The method to calculate daily VKT for a segment is to multiply the length of a roadway segment by the
volume of traffic on that segment. The formula for the daily VKT on a segment calculation is given
below:
Daily VKT = Segment length (km) x Volume on that segment (vehicles per day)
3.2.1 Primary Roadway Definitions
Primary roadways may have different definitions throughout Canada. Generally, they represent
roadways with higher capacity and higher traffic volumes. It is important to establish the clear definition
nationwide.
In Calgary, under the current Calgary Transportation Plan 2009 classification, primary roadways consist
of Skeletal Roads, Arterial Streets, Parkways, Urban Boulevards, Neighbourhood Boulevards and
Industrial Arterials (Figure 1).
11
Skeletal Roads (usually named expressways and freeways) have an emphasis on moving vehicular traffic
over great distances. They typically operate at high speeds (≥ 80 km/h) and have little interaction with
adjacent land uses. The access to these roadways is very limited (every 800 m to 3200 m). Skeletal
Roads usually form a “skeletal grid” across the city with approximately three to five kilometres spacing.
The average annual daily traffic volume (AADT) is usually high (> 50,000 vehicles per day). In 2008, the
AADT on certain segments on Deerfoot Trail was greater than 170,000 vehicles per day.
Arterial Streets, Parkways, Urban Boulevards, Neighbourhood Boulevards and Industrial Arterials
(further referred as Major Streets in the report) have varying degrees of interaction with adjacent land
uses. Open space and natural areas are adjacent to Parkways and Industrial Arterials are located in
industrial areas and have a high percentage of truck volumes. Urban and Neighbourhood Boulevards are
destinations (mixed-land use developments) with a pedestrian-friendly streetscape and high quality
urban design. Arterial Streets provide a direct connection between the communities, to/from major
destinations, and they accommodate all modes of transportation. The intersection spacing varies and
depends on adjacent land use: from 60 m on Neighbourhood Boulevard to a maximum of 500 m on an
Arterial Street. The AADT varies from 10,000 vehicles per day on a smaller Arterial Street to over 50,000
vehicles per day such as on Macleod Trail in 2008. Definitions and other information on roadway
classification can be found in the Calgary Transportation Plan.
Classifying roadways by function (not by name) allows us to define primary roadways that can be
compared nationwide.
12
Figure 1. Calgary Transportation Plan 2009: Road and Street Network
13
3.3 Data Sources
3.3.1 Roadway Segment Lengths Data Sources
The main source of data is the Flow Map GIS database created by the Transportation Data division11.
This database contains single line lengths roadways in Calgary and a 24-hour average weekday traffic
volume on those segments back to 2005. As the Flow Map database includes only primary roadway
segments with a traffic volume ≥ 10,000 vehicles, for the VKT calculation, the database was expanded
with all primary roadway segments that have less than 10,000 vehicles per day (examples in Figure 2 and
Figure 3).
Figure 2. 2008 Flow Map Primary Roadway Network
Figure 3. 2008 Major Streets Missing Links
The source for the missing roadway lengths (green line in Figure 3) from the Flow Map database is the
ArcGIS RoadNet (future TransNet) layer, maintained by Roads, Traffic division. This database contains a
record of the length of roads and streets by roadway classification:
•
•
•
•
11
Freeways and expressways
Major Streets
Collector roadways
Local roadways
City of Calgary. Transportation Planning. Transportation Data division.
14
The existing RoadNet GIS layer represents roadways with a median as two lines instead of one centreline. It also includes all ramps as separate lines. The total length of roads and streets could not be used
from the RoadNet database as that total contains double-counted line lengths (e.g., Deerfoot Trail has
two lines in the RoadNet database). For the VKT calculation, centre-line length is taken only once, as
traffic volumes represent volumes in both travel directions.
The following example illustrates the difference between the RoadNet and Flow Map layers.
Figure 4. Double line example from the RoadNet GIS (red line) replaced with a single blue line in the
Flow Map database
The roadway lengths for the primary roadways network missing from the Flow Map database are
calculated as a difference between the Flow Map layer and a single line from the RoadNet for each year.
The difference is shown separately for each roadway classification, for each year in Tables 3 – 7.
The CTP 2009 introduced the new roadway classification (Figure 1). As only the primary roadway
network is used for the VKT calculation, there is a need to translate the “old” roadway classification into
the “new” roadway classifications:
•
•
Freeways and expressways are Skeletal Roads
Major Streets are Arterial Streets, Industrial Arterials, Urban Boulevards, Neighbourhood
Boulevards and Parkways
This will be done once the new TransNet layer is introduced in 2010. Once the GIS TransNet layer is
adjusted to reflect the new roadway classifications and has the ability to create a centre line, it will be
easier to measure segment lengths in the future. Consequently, the VKT will be easier to calculate.
15
3.3.2 Traffic Volume Data Sources
The main source for traffic volume data is the Flow Map GIS database. This database uses all of the
traffic count data:
•
•
•
manual intersection 6-hour traffic counts;
short-term automatic 24-hour counts;
permanent traffic counting station counts .
In general, the Flow Map (an example shown in Figure 5) database includes expressways and freeways,
Major Streets, special collectors (such as Elbow Drive) and a few local streets with daily traffic volume
greater than 10,000 vehicles per day. The current practice is to exclude roadway segments with less
than 10,000 vehicles per day in the database. The volumes are reviewed each year and compared with
previous years to ensure they are reasonable.
As the Flow Map database represents average daily, weekday traffic volumes, adjustment factors are
developed from the permanent traffic counting stations and automatic 24-hour counts. Those
adjustment factors are then applied to the six-hour manual counts to represent 24-hour volumes.
For more details about the Flow Map database and above-mentioned factors refer to Transportation
Data division.
16
Figure 5. 2008 Flow Map Average 24-hour Weekday Traffic Volumes
17
3.3.3 Traffic Volume Data Source for Primary Roadways with less than 10,000 Vehicles per
Day
For primary roadway segments that are not included in the Flow Map database, the volume is estimated
based on the automatic 24-hour traffic counts from previous years. The following table shows the
estimated weekday daily traffic volume based on the traffic count database. Only primary roadways
with the volumes less than 10,000 vehicles per day are taken into consideration. Transportation Data
division maintains the traffic count database.
Table 2. Recommended Traffic Volumes for Primary Roadways
Roadway classification
Skeletal Roads (formerly expressways and freeways)
Skeletal Roads
Major Streets
Streets (Arterial Streets, Industrial Arterials, Urban Boulevards,
Neighbourhood Boulevards and Parkways)
Recommended weekday volume
(vehicles/day)
7,000
6,200
The statistical analysis of recommended volumes for Skeletal Roads and Major Streets is shown in
Appendix A.
3.4 Daily VKT Calculation and Analysis
To calculate daily (Weekday 24-hour) VKT for Calgary, a VKT database was created using all of the
following sources:
•
•
•
Flow Map database
roadway network GIS database
Transportation Data traffic counts database
The VKT database is maintained as both an ESRI GIS file and an Excel spreadsheet file.
Using the formula from Section 3.2, daily VKT for the years 2005 through to 2009 are calculated as
follows:
Table 3. 2005 Daily VKT Calculation
18
Table 4. 2006 Daily VKT Calculation
Table 5. 2007 Daily VKT Calculation
Table 6. 2008 Daily VKT Calculation
Table 7. 2009 Daily VKT Calculation
Figure 6 shows a growth of 11 per cent in the daily VKT on Skeletal Roads and almost constant VKT on
Major Streets over the five-year period. This is expected, as the largest traffic volumes are observed on
the Skeletal Roads, especially Deerfoot Trail where the total traffic volume on all segments within city
limits increased by 22 per cent from 2005 to 2008.
During the same time period, the Skeletal Roads centre-line length increased from 277 km in 2005 to
291 km in 2009 (an increase of 5 per cent), while the centre-line length of Major Streets grew to 560 km
in 2009 from 511 km in 2005 (10 per cent increase).
19
Figure 6. Daily VKT by Roadway Classification
In 2005, the total centre-line length was comprised of 35 per cent Skeletal Roads and 65 per cent Major
Streets (Figure 7). Out of all daily vehicle kilometres travelled, 60 per cent occurred on Skeletal Roads.
On average, one kilometre of Skeletal Roads centre-line carried more than 47,000 vehicles per day.
As shown in Figure 7, the percentage of Skeletal Roads centre-line decreased to 34 per cent in 2009.
Sixty-one per cent of all daily VKT occurred on Skeletal Roads. On average, one kilometre of Skeletal
Roads centre-line carried 50,500 vehicles per day (approximately 6 per cent increase from 2005). During
the same period, the average traffic volume per one km of Major Streets decreased from 17,500
vehicles per day in 2005 to 16,700 vehicles per day in 2009.
20
Figure 7. Roadway Classification Breakdown
3.4.1 Comparison with the Regional Transportation Model Results
Daily VKT is one of the outputs of the Regional Transportation Model (RTM). The VKT are calculated by
multiplying the number of vehicles on each type of link by the length of the link. For the 2006 base year
(R1163), daily VKT for all vehicles (including commercial vehicles) equals 25,220,000. The values shown
in Table 8 are rounded to the nearest 10,000 VKT. The main reason daily VKT are higher in the RTM by
approximately 8 per cent is that the calculations are based on two different roadway networks. Figure 9
shows the primary roadway network (Skeletal Roads and Major Streets) in the 2006 RTM and Figures 2
and 3 show the 2008 Flow Map primary roadway network and missing links.
Table 8. 2006 RTM Daily Vehicle Kilometres Travelled
Roadway classification
Skeletal Roads
Major Streets
Total
2006 RTM daily VKT
16,780,000
8,440,000
25,220,000
It can be concluded that the proposed methodology is in line with the results from the RTM. The results
from the proposed methodology are based on the observed traffic volumes and could be used for RTM
validation. In the future, an effort will be made to generate identical transportation networks in the
Flow Map and the RTM, as per the CTP 2009 roadway classification.
21
Figure 8. RTM Primary Roadway Network
3.5 Annual Vehicle Kilometres Travelled Definition
Annual vehicle kilometres travelled are calculated by multiplying daily VKT with a daily-toannual conversion factor for each year.
As daily VKT represent a 24-hour weekday traffic volume, a daily-to-annual factor is used (not simply
365) to estimate the annual VKT. By using data from the permanent count stations, the daily-to-annual
factor takes into account traffic volume variations on weekends and statutory holidays on Calgary
roadways.
A formula for the annual VKT calculation is given below:
Annual VKT = Daily VKT x Daily-to-annual factor
3.5.1 Daily-to-Annual Factor
The daily-to-annual factor is estimated from permanent traffic count stations. Currently there are 31
permanent traffic count stations located throughout Calgary, mainly on the Skeletal Roads (Figure 14).
Only stations that were operational all year (365 days) were taken into consideration for the calculation
of this factor.
22
The factor varies for each year (2005-2009) and is shown in Table 9 below. A detailed calculation of the
daily-to-annual factor can be found in Table 18 in Appendix C. This factor can be easily calculated for
each year in the future.
Table 9. Daily-to-Annual Factor
Year
2005
2006
2007
2008
2009
Daily-to-annual factor
326.23
328.69
340.73
337.37
335.16
These factors can be obtained on an annual basis, if permanent count stations are available.
3.5.2 Total Annual VKT per Capita Calculation
To get the annual VKT per capita, annual VKT is divided by population for that particular year
(population source: Calgary Civic Census).
Table 10. Annual Vehicle Kilometres Travelled per Capita
As Figure 9 shows, the annual VKT has a constant increase during the five-year period (12 per cent from
2005 to 2009). However, from 2007 to 2009, the annual VKT increased only by 1 per cent, which may
have been in response to rising fuel prices in Calgary (Figure 15 in Appendix D).
23
Figure 9. Annual VKT in Calgary
Although daily and annual VKT have a steady increase during the five year period, the 2009 annual VKT
per capita is almost the same as the 2005 annual VKT per capita. This is mainly due to the population
increase of 11 per cent over the five-year time period, but also due to slower increase in annual VKT,
especially from 2007 to 2009 (only 1 per cent change). Figure 10 shows the annual VKT per capita over
the five-year period.
Figure 10. Annual Vehicle Kilometres Travelled per Capita
24
Figure 11 shows a relative change in the annual VKT, annual VKT per capita and population growth in
relation to the 2005 base year. Annual VKT growth reached plateau in 2007 while annual VKT per capita
decreased after 2007 due to steady population increase.
Figure 11. Population and VKT percentage growth in Calgary since 2005
25
4.0 Conclusion and Recommendations
Vehicle kilometres travelled has been a key transportation indicator for many years. It is commonly used
by municipalities, provinces, states and countries to measure roadway usage and to plan for future
transportation networks. The VKT correlates directly with urban form and can be used in the strategic
decisions that shape future growth of our cities.
The proposed methodology has several benefits as noted on the following conclusions and
recommendations:
•
Consistent and standardized methodology enables comparison with other cities nationwide.
Establishing a standardized and consistent methodology for VKT calculation within Canada
allows for benchmarking, so values are comparable between cities.
Recommendation: Pursue with TAC and CITE to develop a standardized and consistent
methodology for VKT calculation within Canada.
•
Daily VKT and annual VKT per capita can be estimated annually based on the observed traffic
volumes in Calgary.
By establishing the methodology and calculating the VKT, a good baseline to track the progress
towards achieving the MDP/CTP goals and objectives is possible. Daily VKT and annual
VKT/capita indicators can be measured over time.
Recommendation: Use 2005 as a baseline to track the progress.
•
Consistent and standardized count program provides better quality data.
Establishing a consistent and standardized traffic count program for collecting data on all
Skeletal Roads and Major Streets in Calgary can provide better quality data and better traffic
count coverage within the city.
Recommendations:
o Based on the Figure 14 in Appendix B, identify other locations and include them in the
2010 automatic 24-hour count program.
o It is recommended that traffic counts be obtained on all Skeletal Roads and Major
Streets in subsequent years in order to avoid the errors associated with estimating
volumes for roadways not on the Flow Map.
o Re-create a Flow Map that includes all segments of the Skeletal Roads and Major Streets
to reflect Road and Street Network in Figure 1, even though the traffic volume on
certain segments is less than 10,000 vehicles per day (now the Flow Map represents all
roadways with the volume > 10,000 vehicles per day). This would simplify the Flow Map
and the VKT calculation in the future.
26
•
Calculated daily (weekday 24-hour) VKT values are comparable with the RTM values.
Observed traffic volume values and modelled values are similar and logical. Observed traffic
volume values can be used in the model calibration and validation.
Recommendation:
o Strengthen the relationship between the Forecasting and Transportation Data divisions.
o Use the RTM outputs by trip purpose, such as daily VKT and average trip length at the
Area Structure Plan level.
•
GIS based database is easy to maintain and VKT easy to calculate based on the proposed
methodology annually.
Recommendation: Create a single centre-line attribute in the TransNet layer based on the Flow
Map that can be easily imported as necessary.
•
The definition must always be included with any release of either daily or annual VKT.
It is necessary to be cautious when comparing the VKT/capita indicator due to differences in
calculation methodologies (e.g., different sources, daily vs. annual VKT, which roadway
classification taken into calculation).
•
Reporting relative change in the vehicle kilometres travelled values (percentage or direction of
change either increase or decrease) are more accurate to report instead of reporting absolute
values.
The VKT may be impacted by factors not related to the CTP and MDP and their respective
implementation plans. New economic opportunities or constraints, such as economic boom or
downturn, changes in technology or a massive jump in fuel prices, environmental awareness and social
values changes are all unknown variables that can significantly contribute to a VKT increase or decrease.
In recent years, we have witnessed how high gasoline prices can motivate drivers to drive less and use
other modes of transportation. The three-year VKT review is a part of the regular Monitoring and
Reporting Program of the MDP and CTP.
27
Appendix A – Statistical Analysis of Recommended Volumes on Primary
Roadways with Traffic Volumes under 10,000 vehicles per day
The recommended volume calculations for Skeletal Roads and Major Streets are derived from the
automatic 24-hour counts as the average of the traffic volumes for the period 2002 – 2009 (Table 11).
Note that in 2007, no automatic 24-hour counts were performed on Skeletal Roads that had less than
10,000 vehicles per day.
Table 11. Average Traffic Volumes for Primary Roadways with Traffic Volumes under 10,000 Vehicles
per Day
Roadway Classification
Average Traffic Volume on
Skeletal Roads
Average Traffic Volume on
Major Streets
2002
2003
2004
2005
2006
7,513
6,336
6,760
6,432
5,718
5,659
5,268
5,453
5,717
6,664
2007
6,688
2008
2009
8 Year
Average
8,996
7,549
7,000
7,161
6,660
6,200
Skeletal Roads Recommended Volume Analysis
Based on the automatic, 24-hour counts, an average traffic volume of 7,000 vehicles per day was
computed for Skeletal Roads. As the sample size per year is relatively small, a t-test was used for
analysis. Figure 12 shows the relationship between the average traffic volumes over the period 2002 –
2009 and a recommended volume of 7,000 vehicles per day.
Table 12. Skeletal Roads Average Traffic Volume and Sample Size per Year
28
Average 24-hr Traffic Volume on Skeletal Roads
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
2002
2003
2004
2005
2006
2007
2008
2009
Average Traffic Volume on Skeletal Roads
Recommended Value for Skeletal Roads
Figure 12. Recommended Value for Skeletal Roads with Traffic Volume under 10,000 Vehicles per Day
For the Skeletal Roads, a t-test is used to determine whether the mean (recommended volume) is
significantly different from the 2005 – 2008 samples. The t-test formula is used:
where
T is a t-value,
is an average volume,
μ (mean) is a recommended volume,
S is a standard deviation, and
n is a sample size.
It is assumed that 19 out of 20 times (α = 5 per cent) the recommended volumes is 7,000 vehicles per
day for 2005, 2006 and 2008. No counts on Skeletal Roads with less than 10,000 vehicles per day were
found for 2007.
29
Table 13. Skeletal Roads Recommended Volume Analysis
This test shows that there is no statistical evidence to reject the recommended value of 7,000 vehicles
per day. It is recommended that traffic counts be obtained on all Skeletal Roads in subsequent years in
order to avoid the errors associated with estimating .
Based on the statistical analysis, the average traffic volume of 7,000 vehicles per day is the
recommended value for the VKT estimate on Skeletal Roads.
Major Streets Recommended Volume Analysis
Based on the automatic, 24-hour counts (Table 14), the average traffic volume of 6,200 vehicles per day
was computed for Major Streets. Figure 13 shows the relationship between the average traffic volumes
over the period 2002 – 2009 and a recommended volume of 6,200 vehicles per day.
Table 14. Major Streets Average Traffic Volume and Sample Size per Year
30
Average 24-hr Traffic Volume for Major Streets
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
2002
2003
2004
2005
2006
2007
2008
2009
Average Traffic Volume on Major Streets
Recommended Value for Major Streets
Figure 13. Recommended Traffic Volume for Major Streets
Because the sample size ≥ 30 for each year, the normal distribution is used to calculate the probability
consistent with the Central Limit Theorem:
If is the mean of a random sample of size n taken from a population with mean µ and finite variance
σ², then the limiting form of the distribution of
As n
The following table contains the Z-values for the years 2005-2008. Sample standard deviation (S) is used,
as it is an unbiased estimate of σ (population standard deviation). Higher probability suggests that the
recommended value is a reliable estimate.
31
Table 15. Major Streets Recommended Volume Analysis
Except for 2005, all other years have a high probability of having average traffic volume of 6,200 vehicles
per day.
Based on the statistical analysis, the average traffic volume of 6,200 vehicles per day is the
recommended value for the VKT estimate on Major Streets.
Sensitivity Analysis
Sensitivity analysis was done to ensure that the recommended value for Major Streets provides a
reliable estimate for the VKT calculation.
The analysis was done using the 2009 data and assuming traffic volumes variations (µ ± S). The
recommended value for Skeletal Roads is assumed unchanged for this analysis. It is recommended that
the traffic volumes be measured in the future on all Skeletal Roads. The estimated daily VKT are shown
in Table 16.
Table 16. Daily VKT Calculation using (µ±S) Traffic Volume Variations
32
Table 17 shows that the estimated VKT on Major Streets represent a three to six per cent share of the
total VKT on all primary roadways. That share does not make a significant difference in overall VKT
calculations. It is proposed that a value of 6,200 vehicles per day remains as a recommended value for
Major Streets when a true volume is not available.
Table 17. Major Streets Traffic Volume Sensitivity Analysis
Volume (Vehicles/Day)
Estimated VKT on Major
Streets with traffic
volume under 10,000
vehicles/day
Total VKT on all primary
roadways
Per cent of estimated
VKT on Major Streets
(of total VKT on all
primary roadways)
Recommended volume
(µ)
6,200
1,013,000
Volume (µ+S)
Volume (µ-S)
8,650
1,413,000
3,750
613,000
24,019,000
24,419,000
23,619,000
4%
6%
3%
33
Appendix B – Permanent Traffic Counting Station Locations
Figure 14. 2009 Permanent Traffic Count Station Locations
34
Appendix C – Daily-to-Annual Factors
Average daily-to-annual factors are used to calculate annual VKT. Only permanent count stations that
were operational 365 days were used in the calculation. As can be seen from the table below, the
factors vary depending on traffic volume, year and location within the city.
Table 18. Daily-to-Annual Factor Calculation
35
Appendix D – Average Fuel Prices in Calgary
Fuel prices in Calgary fluctuated over the last five years, reaching their high in 2008.
Figure 15. Fuel prices in Calgary since 2005
Calgary gas prices website accessed April 5, 2010
(http://www.calgarygasprices.com/retail_price_chart.aspx)
36
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