A Statistical Accident

Mon a.m. late

Abstract Remit

The New Zealand Agency (NZTA) investigated the relationship, if any, between school travel plans and improved road safety, in particular for pedestrians and cyclists.  

Using crash data within a 500 m radius around eleven schools in Auckland City over a 10 year period, this assessment indicates that the following decrease in reported crashes occurred since the launch of the travel plans:

_ 57% involving cyclists and pedestrians aged five to thirteen
_ 30% involving all pedestrian and cycling
_ 4% all crashes.

Accordingly, we analysed the crash data within a 500 m radius of eleven similar decile rated and roll size schools in Auckland City over the same period and found the following decrease in reported crashes occurred:

_8% involving pedestrians and cyclists aged five to thirteen
_28% involving all pedestrians and cyclists
_9% all reported crashes between

The average annual social cost of crashes for pedestrians and cyclists between the age of five and thirteen in a 500 m radius around schools with a travel plan was found to be $1,300,200 for the five years prior to the travel plan implementation, with an average annual cost of $551,800 for the years post travel plan implementation, a reduction of almost 60%.

Author Profile 

Quantifying ‘benefits’ and ‘costs’ is an essential element to transportation planning.    Coralie’s Applied (Environmental) Economics degree reflects both her desire to ‘save the world’ and an appreciation that enthusiasm alone may not bring others on board. 

Having developed a passion for Travel Demand Management as a Senior Transport Planner at Auckland City Council, Coralie gained a better appreciation of quantifying transport costs and benefits evaluating transport initiatives for LTNZ (now NZTA) as Principal Planning Advisor.

Coralie’s paper on school travel plan crash statistics, “A Statistical Accident” suggests an unexpected statistical outcome. The outcome in fact is not that unexpected, but is somewhat surprising in terms of its magnitude.

Organisation or Business: 
NZ Transport Agency
Document Type: 
City/Town: 
Presenter: 
Coralie O'Brian
Session or Keynote: 
School Initiatives