HomeMy WebLinkAboutPortola Ave Widening - Whitewater Channel to Hwy 111 CITY OF PALM DESERT
INTEROFFICE MEMORANDUM
TO: City Council and City Manager
FROM: Richard J. Folkers, Assistant City Manager/Public Works Director
SUBJECT: PORTOLA AVENUE WIDENING — WHITEWATER CHANNEL TO
HIGHWAY 111
DATE: October 14, 1999
RECOMMENDATION:
By minute motion, affirm staff recommendation for a reduced right-of-way and roadway
cross-section for Portola Avenue between the Whitewater Channel and Highway 111.
BACKGROUND:
In response to circulation issues raised regarding a proposed change of zone and General
Plan Amendment for a portion of the Portola Avenue corridor, Public Works staff have
undertaken an analysis on the impacts associated with the widening of Portola Avenue.
The City's Circulation Element designates Portola Avenue as a major thoroughfare. As
such, the right-of-way width is specified as 100 feet with 76 feet of roadway improvement
and 12-foot-wide parkways. The lane configuration within the 76 feet improvement width
includes four 12-foot-wide vehicle travel lanes, a 12-foot-wide center (painted) median
lane and two 8-foot-wide parking lanes. This cross section exists for the majority of Portola
Avenue north of the Whitewater Channel.
The segment of Portola Avenue between the Whitewater Channel and Highway 111
consists of a variety of right-of-way and improvement widths ranging from 44 feet of
improvements within 60 feet of right-of-way to 88 feet of improvements within 100 feet of
right-of-way. The roadway striping within this segment varies from a three-lane facility to
five-lane facility, all with no on-street parking and no provisions for bicycle or golf cart
lanes.
General Plan Circulation Element Policy 2.1 states that level of service (LOS) "C" is the
performance objective on the circulation system. For roadways with LOS worse than "C",
the objective is to maintain or improve the level of service. Table 2, "ADT Capacities", of
the Circulation Element indicates that the volume of traffic that can be accommodated at
LOS "C" is 10,000 vehicles per day on a two-lane roadway and 26,000 vehicles per day on
a four-lane roadway.
Page 2
October 14, 1999
SUBJECT: PORTOLA AVENUE WIDENING — WHITEWATER CHANNEL TO
HIGHWAY 111
Traffic volumes have exceeded 17,000 vehicles per day on Portola Avenue since at least
1994. This results in operation at LOS "F" during peak periods in the two-lane
configuration that currently exists. Portola Avenue is carrying all of the traffic that it can at
this time and some traffic may currently be diverting to other routes due to the congested
conditions.
A recent study of Fred Waring Drive found a traffic volume growth rate of approximately
three percent (3%) per year over the last several years. If Portola Avenue experiences a
three percent per year growth rate through 2010, traffic volumes would be approximately
22,000 vehicles per day. If Portola Avenue was widened to four lanes, this would result
in LOS "C" through 2010. If traffic volumes continued to grow at three percent per year,
level of service would drop to LOS "D" by 2017. Of course, traffic volumes do not
actually increase (or decrease) at a steady rate and they may reach these thresholds sooner
or not at all.
In analyzing the impact to existing development within the scenario, staff looked at two
possible scenarios. The first involved full implementation of the General Plan Circulation
Element criteria for Portola Avenue (100' R/W and 76' improvement width). Taking a
conservative, worse case, approach staff has determined that it would be necessary to fully
acquire approximately 19 properties with partial acquisitions involving 64 properties.
Acquisition costs have been estimated in the neighborhood of $3,785,000 plus an
additional $1,654,000 in construction-related costs for a total cost of $5,439,000.
In order to reduce the potential impacts the widening project would have, financial and
otherwise, staff evaluated a second scenario involving reduced right-of-way/improvement
width. As stated previously, a four-lane vehicle travel facility could provide for LOS "C"
beyond 2010. This four-lane facility could be accommodated through 68-feet of
improvement width and 88 feet of right-of-way. The lane configuration within the 68 feet
of roadway improvement would include two 12-foot-wide and two 11-foot-wide vehicle
lanes, a 10-foot-wide center (painted) median lane and two 6-foot-wide bicycle/golf cart
lanes as well as a 10-foot wide parkway area. Again, taking a conservative, worse case
approach, staff estimates that it would be necessary to fully acquire six properties with
partial acquisitions involving 27 properties. These costs have been estimated at
$1,400,000 with construction adding an additional $1,515,000 for a total cost of
$2,915,000.
•
Page 3
October 14, 199
SUBJECT: PORTOLA AVENUE WIDENING — WHITEWATER CHANNEL TO
HIGHWAY 111
With the ultimate goal being to provide an acceptable level of service in a safe, efficient
manner, staff feels that a reduced right-of-way and travel way width can accomplish that
goal while significantly reducing the project impact to existing development.
Staff recommends that the City Council, by minute motion, affirm the concept of reduced
right-of-way and roadway cross-section for Portola Avenue between the Whitewater
Channel and Highway 111.
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411.
RICHARD J. F0 KERS, P.E. REV WED AND CONC R
CITY MANAGER
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