Keith Vodden Dr. Douglas Smith - Transports Canada

Analysis and Estimation of the Social Cost of Motor Vehicle Collisions in Ontario
Next adjustments were made to transfer the number of collisions and the vehicles
involved in them to injury and PDO collisions. The characteristics of a fatal collision
were used to transfer a sufficient number of collisions that would have involved extra
fatalities from injury to fatal collisions. Note that only the number of collisions and their
associated vehicles by damage severity were transferred since the model had already
correctly allocated the extra fatalities and injuries among collision severity categories.
The characteristics of an injury-only collision were used to transfer an appropriate
number of collisions and their associated vehicles by damage severity from PDOs to
injury collisions. A maximum number of collisions was calculated based on which injury
severity category would be the hardest to achieve given the number of injuries allocated
and the proportion of injuries by severity category in the average injury collision. The
number of vehicles by damage severity category was estimated for this maximum number
of collisions. This number of vehicles, subject to the maximum vehicles available by
damage category, was transferred from PDOs to injury collisions. Recall that the model
had already allocated the correct number of injuries to injury collisions based on the
Ontario overall result.
The redistribution of collisions moves injury collisions that would involve
fatalities to fatal collisions and PDO collisions that would involve injuries to injury
collisions while maintaining the total number of collisions. As a result the number of fatal
and injury collisions increases while PDOs declined. The model also keeps the number of
vehicles and the proportion by damage severity constant. However these are redistributed
among collision severity categories. The results of these adjustments are shown in Exhibit
V-2.
Note that the model for pedestrian involved collisions transferred injury to fatal
collisions but no PDOs to injury collisions. Because there were no demolished vehicles in
PDO collisions, no extra injuries were assigned to PDOs by the model and consequently
no collisions and their associated vehicles were transferred to injury collisions.
Data from ORSAR identify 133 PDOs involving a pedestrian and as appropriate
to the definition of a PDO, none involved an injury either to the pedestrian or vehicle
occupants. After adjustment the model continues to retain the 133 PDOs involving a
pedestrian but with no injuries.
B. SOCIAL COST OF MOTOR VEHICLE COLLISIONS RELATED TO
ONTARIO SUB-MODELS
Social costs related to each cost category of the Ontario core model are also
applied to Ontario sub-models. The same flexibility exists over cost parameters as
provided in the Ontario model. The analyst selects the valuation method for human
consequences, values assigned to human consequences, and year in which values are
presented. Social costs presented in this section used the willingness to pay—medium
scenario.
58 TNS Canadian Facts, Social and Policy Research