Traffic study C E O R C E S . NOLTE AND ASSOCIATES
civilPm Engineers • P l a n n e r s • Sur % e y o r s
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STUDY OF TRAFFIC ADEQUACY
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ASSOCIATED WITH
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PROPOSED MARIM MALL REGIONAL SHOPPING CENTER
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June 7, 1973
1731 North First Street P.O. Box S20, San 10GS' "lilornis g6
112. (406) (2 6 7-3 4 001
SAN ja@g • SAN FRANCIgCO • WALNUT CRS8K • SOUTH SAN FRANCISCO • SAN DINGO
STUDY OVERVIEGi
The purpose of this study is to identify the traffic effect of the
proposed Mariani Mall regional shopping center on Saratoga-Sunny-
vale Road (Highwa 9)at its intersections with the Route 280
(Junipero Serra) Freeway ramps. The study was conducted in two
parts.
In Part I the effect of generated traffic on the existing ramp 1
intersections was analyzed. The super-imposition of shopping
traffic upon current traffic resulted in traffic volumes almost
4 double those of 1973. Using procedures prescribed in theRighway
i Capacity Manual, it was determined that forced flow (jammed) traf-
fic operation would result. Until such time as further street
and highway improvements are constructed to reduce dependency on `
the subject interchange, traffic using Saratoga-Sunnyvale Road
would be subject to intolerable delay and congestion.
• Part II focuses attention on several aspects of recently presented
findings of other traffic engineering consultants that require
further resolution. 1975 and 1995 levels of service at the inter-
sections of Saratoga-Sunnyvale Road and the freeway ramps are
1 sensitive to many factors. Among these are the number of trips
generated by Mariani Mall, the distribution and assignment of
these trips, peaking characteristics, and the number of north-south
' through lanes available.
Analysis of work performed by other consultants disclosed some in-
consistencies in these factors. The levels of service reported
in the Barton-Aschman associates study appear to be based on trip
generation factors.: lower than those being used by the consultant
conductinngg the traffic study for the General Plan, on a traffic
distribution and assignment which differ significantly from those
developed in an earlier traffic study for Mariani Mall, and on
• "thr.-ugh traffic" peaking characteristics that are less demand-
ing than the peaking characteristics of today's traffic.
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GtOtGE S NOVIN AND ASSOCIATtS
civil tatlRe rr - Planner* - surveyors
PART I
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TRIP GENERATION
It is estimated that Mariani Mall will generate 5200 trips during
• the evening peak hour (5:00 to 6:00 PM), of which 2600 are trips
in and 2600 are trips out. These estimates are based on trip
generation factors being used by the consultant perfcrming the j
traffic study for the Cupertino General Plan. The trip genera-
I tion factors were applied to the 1,180,000 square feet of floor
I area proposed by the developers.
It is reasonable to assume that, if Mariani Mall is constructed,
many nearby vacant parcels will also develop commercially. The
City has received several expressions of interest in this regard,
particularly from the area west of the Mariani Mall property.
These properties are in various stages of planning; some have had
site plans approved, some have had preliminar•,► site plans pre-
pared, and some have had no site planning whatsoever. There are
approximately 81.5 acres of land susceptible to commercial deve-
lopment in the area between Junipero Serra Freeway and Stevens
Creek Boulevard immediately west of Saratoga-Sunnyvale Road.
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GRORGs S. NOLTs AND ASSOCIATES
Chll squaws 0 ►I..s.r• • s.rr.,or. j
PART II
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aIT P GENERATION
The Barton-Aschman Associates estimates of afternoon ppeeak-hour
• (5 to 6 PM) traffic ggenerated by Mariani Mall are 1,770 vehi-
cles entering and 2,010 leaving based on 1,180,000 square feet
of flaor area. It is our understanding that the generation j
factors used by JHK and Associates in their general plan Work
for both the Mariani Mall and Vallco Park sites are 2.2 trips
in and 2.2 trips out per thousand square feet. Application of
these generation factors results in 2,600 vehicles in and 2,600
vehicles out. Total afternoon peak-hour generated traffic ac-
tivity based on the ggeneration factors being used in the Genera'
Plan studies is 5,200 vehicles, which is 37 percent more than
the 3,780 vehicles in the Barton-Aschman Associates estimates.
TRAFFIC DISTRIBUTION AND ASSIGNMENT
The Barton-Aschman Associates estimates of directional orienta-
tion of Mariani Mall shopping traffic differ significantly from
estimates prepared in 1971. by Donald Frischer and Associates,
particularlyy as these estimates affect the amount of traffic
traveling through the intersections of Saratoge-Sunnyvale Road
and the Junipero Serra Freeway ramps.
GRORGR S NOLTF AND ASSOCIATES
Civil RaRhe.rn - Pl.as*rr - Surveyors
Discussions with the City staff indicate that thetoveed rall
inten-
sity of development for a perarea
squarebf-et of land area. Based
square foot of floor area p approximately 880,000
on this ratio, the 81. 5 acres will support app
square feet of new commercial floor area. It is highly specula-
tive to estimate how much of this potential
all wdevelopment
hich would will probably j
occur prior to completion of MarBasediani ion what has happened in ; .
not occur until at least regional
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the vicinity of other potential, or 22oP000g square rfeettofscommercial i
that 25% of this Applying the same
floor area, will develop during thi.; period.
generation factors used for Mariani Mall (even tpergs square
enerate more trips p q }
shopping areas are known to g it is estimated that the
of floor area than regional centers) s
subject area will generate 1000 trips s during the evening D
e trips out.
hour of which 500 are trips in and 500 ar
Ohviously, near-term development will also be occurring in other
areas tributary to the subject interchange. Because a the traf-
fic study being conducted for the City as part of the General
• Plan work will provide incremental estimates of estimatesaofd on
development in the entire sub-regional area,
no this additional traffic are included herein.
Trip generation estimates are summarized in the following table.
PM PEAK-HOUR TRIP GENERATION
PLANNING AREA FLOOR AREA PM PEAK-HOUR TRIPS (veh./hr.)
s .ft. IN OUT TOTAL
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Mariani Mall
1,180,000 2.1600 2,600 51,200
Area Wesc of Saratoga- 500 500 1,000
' • Sunnyvalf. Road 2209000
PROPOSED STREET AND HIGHWAY IMPROVEMENTS i
Between Stevens Creek Boulevard and Junioero Serra Freeway, Saratoga-
Sunnyvale RoaC will be widen
dwithponlydtwo throughro , on anterim lanes inleach
three lanes in each di on
direction crossing the structure. The California Division of High-
ways has been requested by the City to reconstruct the interchange
to add loop ramps in the northeast and southwest quadrants. This
reconstruction would eliminate the double left-turnad lanesing on the e
structure and enable Saratoga-Sunnyvale
ov
4 lanes in each direction.
An alternative design being fo°nUrdered bbut the
wouldDivision
widenothelst�rucays
would retain the diamond configuration,
ture to provide three through lanes in each direction. Without
interchange reconstruction or bridge widening, only two through
lanes in each direction can be provided.
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GEORGE 8. NOLTE AND ASSOCIATES
Civil Kapneere • Planners a Surveyors
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The State has also been requested to construct a Torre Avenue j
overcrossing of the Junipero Serra Freeway. It is our under-
standing that neither the interchange reconstruction nor the
Torre Avenue overcrossing have been approved, designed or sche-
duled for construction by the State.
Another proposed future improvement is the extension of Route 85
(West Valley) Freeway from Stevens Creek Boulevard southeasterly
to Route 101 (Bayshure) Freev ay. The portion between Stevens
Creek Boulevard and Saratoga-Sunnyvale Road is tentatively sche-
duled for construction in 1978; the portion easterly is unsche-
duled.
TRAFFIC DISTRIBUTION AND ASSIGI*ENT
The distribution estimates devel;,ped for Mariani Mall by Donald
Frischez and Associates in 1971 were used in this analysis.
Because access will be available via local streets, a slight
modification of the Frischer distribution is considered appro-
priate for application to the area immediately west of Saratoga-
Sunnyvale Road. The distributions used for �i riani Mall and I
the area west of it, which are shown in Figure 1, were applied
to generated trips to produce peak-hour assignments.
The extension of West Valley Freeway to Saratoga-Sunnyvale Road
scheduled for 1978 will divert some traffic using the subject s
interchange. For example, tripsT—etween the Cities of Palo Alto
and Saratoga that have not already been diverted to the recent-
ly completed freeway connection at Stevens Creek Boulevard would f
be diverted to a freeway extension to Saratoga-Sunnyvale Road. '
To allow for this possible diversion, the current traffic volumes
executing movements susceptible to diversion have been hal,-red.
Figu•:e 2 shows 1973 peak-hour traffic counts taken by the City
witt the assignments of commercially generated trips superior-
• poseO %hereupon. Analysis of present and anticipated traffic
volumes indicates that traffic will almost double as a result
of trips to and from the proposed co mme rcial areas.
CAPACITY ANALYSIS
The estimated volumes shown in Figure 2 have been analyzed to i
determine the level of service that will result if commercially
generated traffic is added to present traffic. The analysis
indicates that the ramp intersections, which now operated at
level of service "C", will be operating at level of service "F".
Definitions of levels of service are attached.
CONCLUSION - PART I
Because neither the proposed reconstruction of the Saratoga-Sunny-
vale Road interchange at Junipero Serra Freeway nor the construc-
tion of a Torre Avenue overcrossing is scheduled, the existing
interchange will be required to serve newly generated commercial
traffic for several years. This study indicates that traffic de-
mand for this interchange will result in forced flow (jammed)
operation.
CRORC6 B. NOLTE AND A88 e '—
Civil■avinger. • .�r. • surveyors
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GEOME S. NOLTE AND ASSOCIATES FIGURE 1
OISTRISUTION OF TRAFFIC
SAN JO=E WALNUT CREEK • •AN FRANGSCO GENtRAT[D S1r FUTMIt
NMINt)� HU19H•Mf� NAMt11-1tN COM ot*cmL Mvnopm&"T
APPROVED DATE 14•f-1; !GALE No Suit 110.73
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►,1975 Traffic Cwnts token by
cit ona an 3116173(ou�th th ►n m"Tu"a 3. ..
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LEG EW0 mow+ t.s Rttiects passible diversion of
vth. 1>r — half of 1973 volwnt tO extension
of west whey Free way
ovant
TOTA��ROIINOED� o g
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600
6 t ruled by Moriorai Moll
t M' aM Arta FIGURE t
HCHECRID
OEOp43E S. NOLTE AND ASSOCIATES PEAK.NOV1t (3is b pm)
gAN DOSE WALNUT CHEEK gAN FRANCISCO TEArRIE vOWMIts oN NWYi.w,:.?,.00 4.,*:ui n.a AZ INNlPERO SEaR� FREEWAY He scok �. uo •T3
:;ppROYED GATE 1�•Y•13 SCALE
The Barton-Aschman Associates distribution estimates that 38
percent of generated traffic will traverse the ramp intersec-
tions as opposed to 52 percent estimated by Donald Frischer
and Associates. The difference is largely due to their dif-
fering estimates of the usage of proposed Torre Avenue.
Barton-Aschman Associates estimated that 42 percent of site-
�,enerated traffic will use Torre Avenue, whereas Donald
Frischer and Associates estimated 28 percent. Applying the
daily trip generation factor being used by the General Plan
consultant, Mariani Mall will generate 51 , 100 trips per day,
42 percent of which is 22,300 trips per day.
PEAKING CHARACTERISTICS OF THROUGH TRAFFIC
Traffic not generated by Mariani Mall can be considered through
traffic for the purposes of this analysis. The Barton-Aschman
Associates report states an assumption used to convert their
• estimates of 1995 ADT (average daily traffic) to peak-hour
volumes. Among these assumptions is "That the peak-hour split
in traffic would be approximately equal". In other words,
between 5:00 and 6:00 P.M. , northbound and southbound through
traffic volumes on Saratoga-Sunnyvale Road will be equal in
1995. This contrasts with the current spliL , which is approxi-
mately 65 percent southbound and 35 percent northbound. The
even split predicted by Barton-Aschman Associates tends to
reduce lane requirements.
LANE AVAILABILITY ON SARATOGA-SUNNYVALE ROAD AT FREEWAY RAMPS
Bec;;use the existing 8-lane wide structure contains double
left-turn lanes for both the northbound and southbound left-
turn movements onto the freeway, only four lanes (two in each
direction) are available for through movements. The forthcoming
assessment district widening of Saratoga-Sunnyvale Road will
• not affect this limitation; regardless of its width adjacent to
Mariani Mall, the lane availability for through movements at
I the rasp intersections will continue to be two lanes in each
direction until such time as either the interchange or structure
is modified.
The Barton-Aschman study concluded that with traffic generated
by Mariani Mall, the existing (unmodified) interchange will
operate at level of service C' in 1975 and "D" in 1995. These
levels of service are shown in Tables 2 and 3 of their report.
Also shown in Tables 2 and 3 are the number of lanes on each
+ approach to the two intersections. It appears that the number
of north-south through lanes is overstated. The accompanying
i narrative clearly indicates that the levels of service shown
in Tables 2 and 3 pertain to the existing, unmodified inter-
change structure. Until a modification is constructed, t%.o
through lanes will be available for each direction on the north-
bound and southbound approaches to these intersections, as op-
posed to three lanes shown in Table 2 for 1975 and four lanes
I shown in Table 3 (and Figure 11) for 1995.
CEORCE 5. NCILTE AND ASSOr:IA7F.'S
Civil am erg • Pl..n.n • surveyors
tr.
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In order to provide the number of 1995 through lanes stated in
Table 3 and portrayed in Figure 11, while retaining the diamocld
configuration, the structure would have to be widened from
eight to twelve lanes. The "C" level of service reported in
Table 2 for 1975 and the "D" level of service reported in Tale
3 for 1995 may be based on overstated availability of through !
lanes. f.
CON CLUS ION - PART II i
The calculations necessary to estimate levels of service involve
tion and assignment, peaking char
acteristicsnandrnumberaffic doftaribu-
vail-
able lanes. The study findings thus far presented by other core-
; sultants indicate that these factors have not yet been completely f
resolved with respect to Mariani Mall traffic.
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CRORGE S. NOLTE AND ASSOC1ATRS
'-- Clvll tallftovre - ►luwore - surveyors
DEF IN IT IONS OF LEVELS OF SERVICE
Level of service A describes a condi.t-_on of free flow, with
low volumes and high speeds . Traffic density is low, with
speeds controlled by driver desires , speed Liriits , and
physical roadway- conditiuns . 'There is little or no restriction
in maneuverability due tc the presence of other vehicles , and
drivers can maintain their desired speeds with little or no
delay.
Level of service B is in the zone of stable flow, with operating
icpeeds beginning to be restricted somewhat by traffic conditions .
Drivers still have reasonable freedom to select their speed and
lane of cper,ition. Reductions in speed are net unreasonable,
with a low probability of traffic flow being restricted. The
lower limit (io est speed, highest. volume) of this level of
• service has bee.1 associated with service volumes used in the
de3ign of rural Cighways .
Level of service ( is still in the zone of stable flow, but
speeds and maneuv?rabi_lity are more closely controlled by the
higher volumes . must of the drivers are restricted in their
freedom to select their own speed, change lanes , or pass . A
relatively satisfactory operating speed is still obtained, with
service volumes perhaps suitable for urban design practice.
Level of service D approaches unstable flow, with tolerable
operating speeds being maintained though considerably affected by
changes in operating conditions . Fiuctuations in volume and
temporary restrictions to flow may cause substantial drops in
operating speeds . Drivers have little freedom to maneuver, and
comfort and convenience are low, but conditions can be tolerated for
short periods of time.
• Level of service E cannot be described by speed alone, but
represents operations at even lower operating speeds than in
level D, with volumes at or near the capacity of the highway.
At capcity, speeds are typically, but not always, in the neigh-
borhood of 30 mph. Flow is unstable, and there may be stoppages
of momentary duration.
Level of service r describes forced flow operation at low speeds,
where volumes are below capacity. These conditions usually
result from queues of vehicles backing up from a restriction
downstream. The section under study will be serving as a storage
area during parts or all of the peak hour. Speeds are reduced
substantially and stoppe -;es may occur for short or long periods
of time because of the downstream congestion. -In the extreme,
both speed and volume an drop to zero.
From Highwav Capacity Manual, by Highway Research Board.
page 3
The preliminary plans for the area, as represented on drawing CP-3, call fcr
J portion of the park area to be mounded so it forms a na_ural amphitheater,
having a trellised stage as its focal. point. Other sections of the park
provide for a paved plaza for other activities as described below. An
ample number of bike parking blocks will be furnished.
This area is envisioned to be used for commercially-oriented civic and
public activities, such as Scout activities, bake sales, high school and
college art shows, strolling musicians, etc.
• AN/mcr
12-5-72
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