Editing Trip distribution (section)

{{No footnotes|date=May 2016}}[[File:IMG SignR4492829.jpg|thumb|All trips have an origin and destination and these are considered at the trip distribution stage.]]
'''Trip distribution''' (or '''destination choice''' or '''zonal interchange analysis''') is the second component (after [[trip generation]], but before [[mode choice]] and [[route assignment]]) in the traditional four-step [[transportation forecasting]] model. This step matches tripmakers’ origins and destinations to develop a “trip table”, a matrix that displays the number of trips going from each origin to each destination.<ref>Guidance on Transport Assessment https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/263054/guidance-transport-assessment.pdf</ref> Historically, this component has been the least developed component of the [[transportation planning model]].

{| border="1" cellpadding="5" cellspacing="0" align="center"
|+''Table: Illustrative trip table''
! Origin \ Destination	
!1
!2
!3
!Z
|-
|1
|''T''<sub>11</sub>	
|''T''<sub>12</sub>
|T<sub>13</sub>	
|T<sub>1Z</sub>
|-
|2
|''T''<sub>21</sub>
|
|	
|		
|-
|3
|''T''<sub>31</sub>
|
|
|
|-
|Z
|''T''<sub>Z1</sub>	
|
|
|''T''<sub>ZZ</sub>
|-
|}

Where: ''T''<sub>&nbsp;''ij''</sub> = trips from origin ''i'' to destination ''j''.  Note that the practical value of trips on the diagonal, e.g. from zone 1 to zone 1, is zero since no intra-zonal trip occurs.
	  
Work trip distribution is the way that travel demand models understand how people take jobs.  There are trip distribution models for other (non-work) activities such as the choice of location for grocery shopping, which follow the same structure.