Attachment 30 - Traffic Study Information Sheet, prepared by Parks and Public Works Dept
Staff responses are provided below to questions from a Council Member:
Provide an explanation for the assumption of the 700 total daily trips provided in the Alberto Traffic
Impact Report of which 272 are AM and PM peak hour trips.
Traffic engineering utilizes objective standards for traffic analysis, allowing for the Town to follow
identified criteria. These standards, like the ones identified in the Town’s Traffic Impact Policy, are
approved by the Council, creating an ongoing objective traffic analysis across all development projects.
The Town’s adopted Traffic Impact Policy (TIP) requires any Traffic Impact Analysis (TIA) developed for a
Town project to follow VTA’s Transportation Impact Analysis Guideline. This guideline specifies the use
of the most recent version of the Institute of Transportation Engineers’ (ITE) Trip Generation Manual to
develop proposed project trips. Using the ITE tool provides for the quantities identified in the in the
question.
The TIA guidelines require the determination of both AM and PM peak hour traffic trips. This one hour
timeframe in morning and evening is meant to identify the heaviest impact to an intersection. It is this
one hour heavy impact timeframe that is used to measure the impact at each intersection. This impact
is determined to be either less than significant or a significant impact based on the Town’s stated
objective standards in the Town’s Traffic Impact Policy. For significant impacts, the project must make
infrastructure changes to address that impact.
The Alberto project daily trip rate and peak hour trip rate were developed using the objective standards
in the ITE manual. The additional daily trip rate for the previously proposed 93,500 SF new office
building was calculated at 700 daily trips. The peak hour A.M. trips were calculated at 134 trips and the
peak hour P.M. trips were calculated at 138 for a total of 272 trips.
These numbers are meant to show the short-term timeframe where there is the biggest impact as well
as the total vehicle trips that can be expected over the course of a day. Keep in mind that the A.M. and
P.M. peak periods are two hours in the morning and two hours in the evening, so most of the trips
generated from the proposed use are within those peak hours.
Explain the assumptions and analysis that led to the traffic report’s conclusion than certain
percentages of the traffic are coming from the different directions.
The TIA forecasts the travel direction of project-generated trips to and from the project site. The
forecast is estimated based on the judgement of the traffic engineer professional developing the
forecast and the work of the developer’s engineer is then independently reviewed by both the Town’s
traffic consultant and the Town’s Traffic Engineer. A traffic engineer typically examines the existing
traffic pattern, roadway network, and project land use in order to develop an estimated trip distribution.
The forecast developed for the Alberto project showed that most the traffic traveling to the project site
would come from southbound Highway 17. Based on historical knowledge and review of past Town
traffic information, the Town’s Traffic Engineer and Town’s Traffic consultant agree that the TIA forecast
reflects similar existing traffic patterns as seen during commute hours in the Town.
ATTACHMENT 30