A1) Estimate
Trip Generation
Each planning application requires a transport assessment
(TA) or transport statement (TS) to be undertaken.
In each case the process includes an estimate of trip
generation and mode split (see DfT’s
Guidance on Transport Assessment for details
of how and when to prepare a TA or TS).
Data in the TRICS® database is used in combination
with other relevant data to determine these estimates.
In some circumstances it may be appropriate to utilise
a first principles, or lifestyle analysis approach
to help determine the trip rates.
It should be noted that most trip generation databases
currently contain little information for sites with
effective Travel Plans in operation. Due to these current
data limitations it may be necessary to calculate the
likely trip generation for a proposed site, assuming
no Travel Plan will be implemented. A revised figure
can then be calculated to account for the impact of
an effective Travel Plan. Naturally, the expected impact
of the Travel Plan will depend on the specific opportunities
for trip reduction and for mode transfer.
It is essential that the methodology used to determine
the trip generation figures and mode splits is logical,
transparent and explained concisely in a manner easy
to understand.
The local authority will need to validate and agree
the trip generation estimate before the data is used
to establish appropriate targets.
If required, it is possible to provide trip generation
and mode share estimates through the TRICS® Bureau
Service.
A2)
After Survey Following the before survey the Travel
Plan will be implemented. The Travel Plan will
be more successful if it is designed with the
results of the survey in mind – for example,
if there are many staff living a short distance
from work, it might target a shift to walking
and cycling.
An after survey will be required following the operation
of the Travel Plan for a reasonable period of time
(as determined by the local authority, dependent on
the specific circumstances of the application). As
a guideline, DfT recommend a minimum period of 1 to
2 years to achieve an effective Travel Plan. For new
developments, it may be important to wait until the
end of the occupational period or until a specific
development phase is complete.
The after survey carried out is a repeat of the survey
carried out in Step 1. To ensure consistency and reliability,
the after survey should be carried out during a similar
period of the year and on the same day of the week
as the before survey.
A3)
Analyse Survey Results A statistically robust comparison
of the baseline predicted trip rates with the
actual trip rates can now be made.
From this analysis it will be possible to determine
transfers between modes and any significant reductions
in trip rate. The trip rates can be calculated and
analysed according to the targets set, for example
per person, or per gross floor area.
On request TRICS® can produce a summary report
detailing the analysis of the two surveys and the degree
to which the targets have been met. The LPA (local
planning authority), LHA (local highway authority)
or HA (Highways Agency) may be asked to provide details
of the targets agreed.
In cases of dispute ACT are able to act as independent
arbiters to verify the results of the analysis and
to consider any mitigating circumstances.
