Wellington Transport Analytics Unit — Glossary & Measure Calculation Methodology

This page defines key acronyms and terms used across the WTAU Continuous Monitoring Dashboards and provides formulas for any key measures not shown directly in the dashboards.

Acronyms

Highway Traffic Volume Dashboard > Measures

Public Transport Volume Dashboard > Dimensions

Crowding Dashboard > Dimensions

Highway and PT Travel Times Dashboard > Dimensions > Measures

Wellington CBD Cordon Dashboard > Dimensions > Measures

Acronyms

PT	Public Transport
SH	State Highway
HV	Heavy Vehicles
N2P	Ngauranga to Petone
ToD	Time of Day
DoW	Day of Week
TA	Territorial Authority

Highway Traffic Volumes Dashboard

Measures

Traffic Change / Growth Rate

This measure shows how much the average traffic volume of the current year has increased or decreased compared to the selected base year, expressed as a percentage. The formula is:

(Current Year Traffic Volume - Base Year Traffic Volume) / Base Year Traffic

% of Weekday Peak Hour Volume

Step 1: Calculate the average weekday peak hour volume over the selected time range. The weekday is defined as the weekday outside of public holidays and school holidays.
Step 2: Calculate the average hour volume across the selected time range.
Step 3: Calculate the percentage of Weekday Peak Hour Volume, and the formula is: average hour volume / average weekday peak hour volume

Percentage of Peak Hour Volume by Day of Week and Time of Day

Step 1: Calculate the average volume over the selected time range.
Step 2: Calculate the maximum average hourly traffic volume, across all hours of the day.
Step 3: Calculate the percentage of peak hour volume, and the formula is: average volume / maximum average hourly traffic volume of the day

Public Transport Volumes Dashboard

Dimensions

WD	Weekday (excluding public holidays)
WE	Weekend (including Saturdays, Sundays and public holidays)
IP	Inter-peak
ON	Overnight

Crowding Dashboard

Dimensions

Capacity	Ratio of passengers onboard to seats available
Crowding level of service	Alphabetical scale A-F based on the ratio of pax to seats A [0, 0.50] No need to site next to anyone B (0.5, 0.75] Choose where to sit C (0.75, 1.00] A seat is available D (1.0, 1.25] May need to stand but comfortable E (1.25, 1.50] Maximum scheduled load F (1.5, ∞] Crush load
AM Peak	06:00 - 09:00 weekdays
PM Peak	15:00 - 18:00 weekdays
Inter-peak	09:00 - 15:00 weekdays
Overnight	18:00 - 06:00 weekdays

Highway and PT Travel Times Dashboard

Dimensions

AM Peak	06:00 - 09:00 weekdays
PM Peak	15:00 - 18:00 weekdays
Inter-peak	09:00 - 15:00 weekdays
Overnight	18:00 - 06:00 weekdays

Measures

Variability	(75th percentile travel time - 25th percentile travel time) / (mean travel time). How much variation is there between the fastest and slowest trips for a given time period.
% of Free Flow	Travel time relative to an unimpeded trip time under 'free-flow' conditons. Free-flow conditions are defined as the average 07:00-08:00 travel time on weekends.
PT / Car Ratio	Relativity between PT travel time (or speed) and car travel time (or speed) for a given corridor

Wellington CBD Cordon Dashboard

Dimensions

AM Peak	06:00 - 09:00 weekdays
PM Peak	15:00 - 18:00 weekdays
Inter-peak	09:00 - 15:00 weekdays
Overnight	18:00 - 06:00 weekdays
Weekend Day	09:00 - 18:00 weekends
Weekend Overnight	18:00 - 09:00 weekends
Site	Point location where vehicles are detected (aggregation of one or more detectors)
Screenline	Geographic line where vehicles movenents across (in each direction) are detected (aggregation of one or more sites)
Cordon	Geographic polygon where vehicle movements in and out are detected (aggregation of one or more screenlines)
NetBI	Metlink's electronic ticketing dataset

Measures

Average Daily Passengers (ADP)	Average of passengers onboard by date
Year-on-year % Change	Percentage change from previous year for selected month(s): (ADP - ADPprev year)/ADPprev year
% Change from 2019	Percentage Change from 2019 (base year) for selected month(s): (ADP - ADP2019)/ADP2019
Bus / Rail Cordon Count – AM Inbound	Derived Measure from electronic ticketing data to replicate historic cordon survey counts. Data is the average daily passengers filtered to: 07:00 – 09:00 AM Tuesday – Thursday Inbound towards the CBD

Have a look at our ongoing projects

We provide documentation relating to all model updates so that interested parties can understand how the models have evolved through time. Let's have a look!