HomeMy WebLinkAboutItem 7.1 DB@SilvergateIntersctn (2)CITY OF DUBLIN
AGENDA STATEMENT
City Council Meeting Date: November 26, 1990
SUBJECT:
Dub]in Boulevard/Silvergate Drive Intersection
(Report by Public Works Director Lee Thompson)
EXHIBITS ATTACHED:
1) Schematic diagram of proposed improvements
2) Excerpt from Resol.ution 130-89 Hansen Ranch
Tentative Map approval
3) Excerpt from Resolution 79-90 Don]an Canyon
Tentative Map approval
4) September 27, 1989, memorandum from TJKM
5) Additional exhibits which compare existing
conditions with proposed improvements will be
displayed at the meeting
RECOMMENDATION:
1) Review schematic design and approve in concept or
direct Staff to make modifications.
2) If the City Council concurs that the proposed
design is appropriate and wishes to proceed with
the preliminary and design engineering work during
the 1990-91 fiscal year, the City Council should
(a) authorize the new Capita] Improvement Project
and (b) authorize a budget transfer in the amount
of $24,600 from the San Ramon Road Phase IV
project to the Dublin Bl.vd./Silvergate Drive
Intersection project.
3) If the City Council authorizes Staff to proceed
with the design process, it is further recommended
that the City Council direct Staff to include this
project in the 1991-92 update of the Five Year
Capital Improvement Program for construction in
FY1991-92.
FINANCIAL STATEMENT:
The preliminary estimated cost of modifying the Dublin
Boulevard/Si].vergate Drive intersection is as follows:
Preliminary Engineering (topo) $ 5,000
Design 19,600
Construction 164,600
Inspection 7,000
Construction Staking 8,000
Total: $204,200
The Capita] Improvement budget does not contain funds
to design and/or construct these improvements within
FY 1990-91. A budget transfer would be necessary to
start the design process in this fiscal year.
Costs incurred are proposed to be reimbursed by
private developers at the time of development.
DESCRIPTION: At its November 13, 1990, meeting, the City Council
directed Staff to prepare a report regarding the estimated cost of engineering
and construction for modifying the Dub]in Bou]evard/Si]vergate Drive
intersection to a normal "T" configuration.
These improvements are presently proposed to be paid for by the developers of
the Hansen Ranch, Don]an Canyon, and other West Dublin housing projects. At
this point, only the Hansen and Don]an projects have been approved. Economic
concerns have caused these developers to de]ay the projects, thus delaying
modification of the intersection. The ttansen Ranch developers are tentatively
proposing to begin construction in the spring of 1991.
ITEM NO.~__
COPIES TO: TJKM
The conditions of approval for the Hansen Ranch development require a 23.7%
contribution to the modification of the Dub]in Boulevard/Silvergate Drive
intersection and to the widening of Dublin Boulevard at that intersection
prior to the occupancy of any units. Donlan Canyon's contribution is defined
as a pro rata share, al.so to be paid prior to occupancy. TJKM's report dated
September 27, 1989 (Exhibit 4) indicates the percentage to be contributed by
each development, including West Dublin.
At the November 13, 1990, City Council meeting, the issue of safety at the
existing DubJin Bou]evard/Si]vergate Drive intersection was discussed. TJKM
recommended, and Staff wi]]. proceed to install, an advisory curve warning sign
for the right turn movement from westbound Dub]in Boulevard onto Silvergate
Drive in an effort to slow the drivers making that turn. Once the
intersection has been reconfigured, drivers will be forced to negotiate the
turn at a slower speed because of the removal of the sweeping curve.
The preliminary estimated cost of design, inspection, and improvements for the
intersection reconfiguration only (not including the cost of widening Dublin
Boulevard, which is also proposed to be paid by developer contribution) is
just over $200,000. It is anticipated that the design process would require
about three to four months to complete.
Staff recommends that the City Council:
(1)
(2)
Review the schematic design for reconfiguration of the
intersection and either approve the design in concept or direct
Staff to make modifications. Plans and specifications would be
returned to the City Council for final approval prior to bidding
the project for construction.
If the City Council approves the schematic design and wishes to
proceed with preliminary and design engineering work, the City
Council should (a) authorize the new Capital Improvement Project,
and (b) authorize a budget transfer in the amount of $24,600 from
the San Ramon Road Phase IV project to the Dublin Boulevard/
Si]vergate Drive Intersection project.
If the City Council proceeds with Option 2 above, it is further
recommended that the City Council. direct Staff to include the
Dub]in Bou]evard/Si]vergate Drive intersection modifications in
the draft Five Year Capita] Improvement Program for construction
in FY1991-92 at the time that the Capital Improvement Program is
updated in June of 1991.
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13:LU
41.
42.
43.
right-of-way where this work is not covered under the
improvement plans.
Street width standards shall be not less than the
Alameda County standards. "A", "B", "D" and "E"
streets shall be considered 2-lane collectors. "C"
Street shall be considered a 2-lane minor street, for
these purposes.
Street names shall be submitted and processed through
the Planning Department and shall be indicated on the
Final Map.
The Developer shall furnish and install street name
signs, in accordance with the standards of the City of
Dublin, bearing such names as are approved by the
Planning Director. The subdivider shall furnish and
install traffic safety signs in accordance with the
standards of the City of Dublin.
OFF-SITE IMPROVEMENTS
44. Prior to release of occupancy, the developer shall be
responsible for the construction of an additional
right-turn lane and related signal modifications on the
west leg of eastbound Dublin Boulevard at the San Ramon
Road intersection. This cost shall be split between
this development and the development of the Blaylock,
Gleason, Fletcher property immediately to the west, on
a pro rata basis based on the amount of traffic
generated by each development.
45. Prior to approval of the improvement plans and Final
Map, the Applicant/Developer shall submit documents
satisfactory to the City of Dublin evidencing
irrevocable public access on the proposed road across
the Valley Christian Center property. Said documents
shall be subject to City Attorney review and approval.
46. Prior to release of occupancy of any units, the
Applicant/Developer shall be responsible for the
project's proportionate share (23.7%) of the cost for
the widening of the existing Dublin Boulevard roadway,
approximately 15 feet, all on the south side, between
Silvergate Drive and Hansen Drive to a~commodate four
12-foot traffic lanes, two five-foot bike lanes, and a
five-foot sidewalk, as generally shown on the proposed
widening plans prepared by TJKM and dated received
August of 1988 and described in the study prepared by
TJKM in memo dated September 27, 1989. The costs shall
be determined prior to release of occupancy.
Prior to release of occupancy of any units, the
Applicant/Developer shall be responsible for the
- 9 .~. ~:,.!'. ~?'~ ~
47.
48.
UTILITIES
49.
50.
51.
52.
WATER
53.
54.
project's proportionate share (23.7%) of the cost of
the redesign of the existing Dublin Boulevard/
Silvergate Drive intersection to form a "T"
intersection with Dublin Boulevard becoming the through
road and Silvergate Drive becoming controlled by a
"Stop" sign as generally shown on the plans prepared by
TJKM dated received August 1988 and described in the
study prepared by TJKM in memo dated September 27,
1989. The cost shall be determined prior to release of
occupancy.
Developer shall prepare legal descriptions for the
application to annex Dublin Boulevard into the City of
Dublin between Silvergate Drive and the west end of
Dublin Boulevard, and for the S%ate of California to
relinquish Dublin Boulevard to .fhe City.
Electrical, gas, telephone, and Cable TV services,
shall be provided underground to each lot or building
in accordance with the City policies and existing
ordinances. All utilities shall be located and
provided within public utility easements, sized to meet
utility company standards, or in public streets.
Prior to filing of the grading and improvement plans,
the developer shall furnish the Public Works Director
with a letter from Dublin San Ramon Services District
(DSRSD) stating that DSRSD has agreed to furnish water
and sewer service to the development.
Secure DSRSD agreement to maintain the on-site sanitary
sewer collection system excluding individual laterals.
The system shall be designed as acceptable to DSRSD.
All utilities to and within the project shall be
undergrounded.
Water facilities must be connected to the DSRSD system,
and must be installed at the expense of the developer,
in accordance with District standards and
specifications. All material and workmanship for water
mains, and appurtenances thereto, must conform with all
of the requirements of the officially adopted Water
Code of the District, and will be subject to field
inspection by the District.
Any water well, cathodic protection well, or
exploratory boring shown on the map, that is known to
exist, is proposed or is located during the course of
field operations, must be properly destroyed,
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OFFSITE IMPROVEMENTS
52. Prior to approval of the improvement plans and Final Map the
developer shall submit documents satisfactory to the City of
Dublin presenting proof of public access on the proposed road
across Parcel "C"
53. Construct 35 foot radius cul-de-sac at the end of Dublin
Boulevard. The new curb and gutter shall not be constructed any
closer to Interstate 580 than the existing curb.
54. Provide a 2" AC overlay on Dublin Boulevard in front of the
Donlan Canyon project. The overlay shall include placing paving
fabric between the existing pavement and the overlay.
55. Remove the existing AC berm on the north side of Dublin Boulevard
from the proposed turnaround to Silvergate Drive and replace with
Alameda County Standard Curb, Gutter and 5 foot wide sidewalk.
56. The Applicant shall obtain Caltrans approval for any work
performed within their right-of-way, or affecting their
facilities (i.e., tying into their cross-culvert, etc.) .
57. Prior to release of occupancy of any units, the developer shall
be responsible for contribution towards cost of the design,
construction'and inspection of an additional right-turn lane
including right-of-way and related signal modification in the
west leg of eastbound Dublin Boulevard at the San Ramon Road
intersection. This cost shall be split between this development
and the development of the Hansen Hills property immediately to
the east, on a pro rata basis based on the amount of traffic
generated by each development.
Prior to release of occupancy of any units, the developer shall
be responsible for contribution towards cost of the design,
construction and inspection of the widening of the existing
roadway of Dublin Boulevard approximately 15 feet, all on the
south side, between Silvergate Drive and Hansen Drive, to
accommodate four 12-foot traffic lanes, and two five-foot bike
lailes~ and a five-foot sidewalk, as generally shown on the
proposed widening plans prepared by TJKM and dated received
August of 1988 and described in the study prepared by TJKM in
memo dated September 27, 1989. This work shall also involve
reconstructing the intersection of Dublin Boulevard and
Silvergate Drive to form a "T" intersection, with Dublin
Boulevard being the through road. This cost shall be split
between this development and the deve].opment of the Hansen Hills
property immediaLely to the east and development of West Dublin
on a pro rata basis based on the amount of traffic generated by
each development.
59. The developer shall be responsible for paying his fair share
towards the cost of the design, construction and inspection of
58.
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MEMORANDUM
DATE:
TO:
FROM:
SUBJECT:
September 27, 1989
Maureen O'Halloran
Michelle DeRobertis
PA 89-062 Hanson Hill Ranch - Update of Traffic Impacts to Dublin
Boulevard Due to Most Current Proposals for Hanson Hill Ranch and
Donlan Canyon
At your request, this memo presents an update of the impacts of the Hanson Hill
Ranch and Donlan Canyon projects and other potent/al developments on the
intersection of Dublin Boulevard/Silvergate Drive and on Dublin Boulevard between
Hansen D~ive and Sflvergate D~ve.
The current proposal for Hanson Hill Ranch is 190 single-family dwelling units. The
current proposal for Donlan Canyon is for 17 single-family dwelling units with
access through the Hansen Hill Ranch property and 300 apartment units with
access directly to Dublin Boulevard.
In addition to the Hanson Hill Ranch and Donlan Canyon projects, there is a
proposal for the West Dublin Hills for a total of 4,443 dwelling units (d.u.). (The
Cronin parcel is included in the West Dublin totals, and is assumed to have 143 d.u.)
The majority of this traffic would use the ][-580 Eden Canyon interchange or the
proposed 1-580/Schaefer Road interchange. However, since Dublin Boulevard would
be extended westerly to Sheerer Road, a p, ortion of the traffic generated by this
'project would use Dublin Boulevard between Silvergate Drive and Hansen Lane.
The future daily traffic volumes on Dublin Boulevard east of Silvergate Drive with
existing plus Hanson Ranch plus Donlon Canyon traffic would be 7,249 vehicles per
day (vpd), which would be Level of Service (LOS) C. LOS C is an acceptable
condition for collectors and minor arterials. If the proposed development in West
Dublin is approved and developed as described, the future daily traffic volumes on
Dublin Boulevard east of Silvergate Drive would be 9,454 vpd, which would be.
LOS E, which is considered a significant impact. (Although LOS E is clearly an
unacceptable condition, it is desirable for collectors and minor arterials to remain at
LOS C or better; therefore, mitigation for Dublin Boulevard east of Silvergate is
recommended when conditions become LOS D.) Therefore, although the existing
Dublin Boulevard would suffice for existing plus Hanson Ranch plus Donlan Canyon
traffic only, the cumulative effect of the Hanson Ranch project, the Donlan Canyon
project emd the West Dublin project would result in adverse traffic conditions on
Dublin Boulevard east of Silvergate Drive where it is currently a two-lane section,
4637 Chabo[ Orive. Suile 214. Pleasan~on, Calitornla 9,
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Mom-eon O'Halloran -2. September 27, 1989
i.e. between Silvergate Drive and Hanson Lane. It would become LOS D when the
West Dublin Project is 38 percent built and occupied and would become LOS E when
the West Dublin Project is 84 percent built and occupied.
To mitigate the significant adverse impacts of the development of these three
projects, this section of Dubli~ Boulevard would need to be widened to have four
lanes, (In addition, Dublin Boulevard between Hanson Lane and Donlon Way would
requiro re-striping to have four through lanes; it is presently wide enough to
accommodate four lanes). The daily traffic volumes on Dublin Boulevard east of
Silvergate Drive and the relative percent shares of the three future projects are
presented below. Two percent shares are presented. The first is the project's
percent share of all new traffic including the cumulative, projects approved prior to
Hanson Ranch. The second is the relative percent of only the three projects under
consideration in this memo: Hanson Ranch, Donlon Canyon and West Dublin. The
latter percent may be appropriate to use to determine the cost shares since the
cumulative projects approved prior to Hanson Ranch have already contributed funds
to other improvements which will benefit the three new projects as well.
~ource
1988 existing
Traffic Volume on
Dublin Boulevard
e/o Silverga .to Drive
3,840 vpd
Percent Share
of all,
New Traffic
Percent Share
of three
New Projects
Cumulative
(Approved prior
to Hanson Ranch)
493vpd
8.8
Hanson Ranch
(190 Single-Family
DwellLng Units)
1,214 vpd
21.6
28.7
Donlan Canyon
(300 apts. +
17 Single-Family
Dwelling Units)
.1,702vpd
30.3
33.2
West Dublin
TOTAL
9,454 vpd
39.3
100.0
_43.!_
100.0
vpd = vehicles per day
( ¸(
Maureen O'Halloran -3- September 27, 1989
The intersection of Dublin Boulevard/Silvergate Drive would also need to be
redesigned to accommodate the increased traffic volumes from any of these three
projects. If the intersection remains as is, the future franc volumes generated by
any of the three projects would cause a significant adverse impact on its operating
characteristics. '
The recommended redesign, previously submitted t~ the City, would make Dublin
Boulevard the main through route at the intersection, and Silvergate Drive would be
the side street controlled by a STOP sign. Based on our professional judgment, this
would improve the operating characteristics d£ the intersection including safety,
which camaot be measured quantitatively, rather than the capacity per se. This
redesign would be necessary with Hanses Ranch and/or Donlan Canyon traffic only,
i.e. even without the West Dublin project, although the West Dublin project .would
be a prime beneficiary of Uae improvemen~ as We'll. The peak hour traffic volumes at
the intersection of Dublin Boulevard/Silverga~te Drive and the relative percent
shares of the three future projects are presente&below.
Traffic Volume at : Percent Share
Dublin Boulevard/' Percent Share of three
Source Silvergate Drive of New Traffic New Projects
11286 existing 286 vph :
Cumulative
(Approved prior
to Hansen Ranch)
Hansen Ranch
(190 Single-Family
Dwelling Unit~)
Donlan Canyon
(300 apts. +
17 Single-Family
Dwelling Units)
185 vph
121 vph
160 vph
27.0
17.6
23.3
24.2
31.9
West Dublin 220 vph
TOTAL 972 vph
32
100.0
43.9
100.0
vph = vehicles per hour
If you have any questions, please give me or Chris a call.
mah
157-001