HomeMy WebLinkAboutGATEWAY TO HARMONY ROAD PUD - PRELIMINARY - 1-88A - CORRESPONDENCE - TRAFFIC STUDY•
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DATE: April 15, 1988
MEMORANDUM
TO: Tom Peterson, Planning Director
FROM: Richard L. Ensdorff, Transportation Administrator��
RE: Harmony Road Access for the Gateway at Harmony Road PUD Proposal
In review of the site plan for this proposal I have reviewed the requested
access on Harmony Road between College Avenue and Mason Street and have
found that I cannot recommend approval of this access for the following
reasons:
o Harmony Road is designated in the City's Master Street Plan as a major
arterial. As such, it is important to provide an improved flow for
traffic even above our arterial standard. The City standard design
speed for major arterials is 50 mph. The proposed access to this
project on Harmony requires a deceleration lane that is designed to
adequately handle the posted speed on this roadway. The posted speed
that we believe is appropriate for a major arterial is 40 mph. The
applicant in the analysis of this access (see attached memorandum dated
February 8, 1988) indicates that their design for the proposed
deceleration lane is equivalent to 26 mph, using the City standards.
This significant variation from the City standards is unacceptable.
o Other sections of major arterials that we have had an opportunity to
review for access control have been required to meet the City standard.
Case in point is Arbor Plaza on the south side of Harmony. No access
points were approved in this development between Mason and College.
College is also designated as a major arterial. Over the past several
years, we have required all development to meet major arterial standards
for approval of the design of access points. An example would be the
Pavilion shopping area.
In the February 8 memorandum from the developer, the developer's traffic
engineer indicates that data from a policy on geometric design of
highways and streets (ASSHTO) provides supportive data that would
justify a deceleration lane of approximately 160 feet. I believe that
this supportive data is out of context and does not reflect the
appropriate reference to determine design of deceleration lanes. The
City standard for deceleration lanes is taken from the same ASSHTO
Design Guidelines and I believe is the appropriate reference to be used
in determining the length of a deceleration lane such as the one
proposed on Harmony Road.
In conclusion, I feel that the request for an access on Harmony Road in
this location does not meet our design standards for a major arterial and
therefore would have a negative impact on traffic flow in this area. I
would recommend that the access on Harmony not be approved.
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MEMORANDUM
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To: Ed Zdenek: , Z''•:!FK
Rick: Ensdor•ff, Fort Collins Traffic Engineer
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From: Hatt Del ich `i'4Jb
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Date: February 8, I _8
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Subject: Harmony Road right -in/right-out access to the
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This memorandum documentsmy research and analysis
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with regard to the proposed Harmony Road right-i n/r i ght-
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out access to the McDonald'= site. City Staff requested
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information regarding the deceleration lane geometr i cs
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for this. access point. The design _Feed for Harmon:, --
Road was assumed to be mph which is the existing
posted speed of the street. The proposed .access is
between College Avenue and Mason Street. The centerline
distance between these two streets is 540 feet. It is.
assumed that the City Staff would require a. "pedestrian
bulb" at the College/Harmony intersection. This would
require that the taper +or• the deceleration lane could
begin no closer than 50 feet from the flow line can the
west side of College Avenue. Ideally, the City Staff
would like the proposed right-in/eight-out access,
designed to cr i ter i a. set forth in the State Highway
Access Cade. If these =.ta.nda.rds can not be met, ether
criteria/standards/examples should be provided with
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regard to the necessary deceleration lane.
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For the 25 mph design speed, the State Highway
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Access Code requires. a deceleration lane of c._,_� feet
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plus 120 feet of taper Qot.al - 355 feet? using .a 15 mph
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turn at the access point. A 15 mph turn requires a. curb
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return radius of 40 feet. The deceleration lane based
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upon these cr i ter ia. would place the right-in/right-out
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accessa.cces.s approximately 70 feet from the centerline of
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Mason Street. This is unacceptable to all parties.
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concerned with this access.
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In order to have a. developable lot on the northeast
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corner of the Harmony/Mason �n intersection, the centerline
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of the proposed right-in/right-out .a.cces.s must. be
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approximately 150 feet east of the east right-of-way of
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1':1.a.s.on Street. Assuming a 30 foot wide access, .a totals
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125 feet are available for deceleration and taper.
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According to Design Cr• i ter i .a. .and Sta.nd•ards• for Streets,
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City of Fart Collins., July 1 86, Section 1.02.08,
Deceleration Lanes. - Arterial Street'_., the deceleration
lane plus taper is 250 feet for 30 mph and 370 feet for.
40 mph. Using the 310 feet r250 + =:70 ; ^? for 35 mph,
it can be seen that the Fort Collins standard cannot be
met. According to A Policy can Geometric Design of
Highways and Streets, AASHTG, IF64, pg. 874,
"The length of the auxiliary lanes for turning
vehicles consists of three component..: (1 )
deceleration length, r21 storage length, and
(3) entering taper. Desirably, the total length
of the aux i 1 i a.r•y lane should be the sum of the
length for these three component_. Common
practice, however, is to accept a. moderate amount
of deceleration within the through lanes and to
consider the taper as .a part of the deceleration
length. Where intersections occur as frequently
as four per mi 1 e , it is customary to forego most
of the deceleration length and to provide only
the storage length plus taper."
According to � Figure 1, copied from A Policy can Geome tr• i c
Design of Highways and Streets, r=ASHTO, 1?$4, pg. 36,
the distance needed to comfortably slow a vehicle
travel 1 i ng 35 mph, (speed on Harmony) to a 15 mph turning
speed is 160 feet. Given this, the length of decelera-
tion lanes should be at least 160 feet. Since accesses
along both of these streets are more frequent than four
per mile, this distance includes the taper. Storage
length is not required on a. right -turn lane of this type
since vehicles will not be delayed in entering the site.
Given that there is 1?5 feet available for deceleration
lane and taper, this distance should be used. The
portion devoted to full width deceleration lane and the
portion devoted to taper is an engineering .judgment. P
the taper length is as short as possible, then the
exiting vehicle can fully utilize the full width of the
deceleration lane being fully removed from the right
through lane. This more abrupt type of design of the
taper offers improved driver commitment to the exit
maneuver and also contributes to driver security and
safety because their vehicle can be fully out of the
through lane. The shortened taper can only be
introduced at lower design speeds and in urban
situations, where frequent exits to deceleration lanes
are common place .and expected. Offering early exit to a,
full width deceleration lane could also improve the
capacity of the arterial street because the _low-down
interference to the through lane would be diminished.
Using a. symmetrical reverse curve design {from
Figure 1 -65C: in A Folic;, on Geometric Design of
Highways and Streets, with a. radius of 150 feet, a. taper
length of 86 feet for a 12 foot lane results. This
allows 10=' feet MY - 66Q of full width deceleration
lane at this location. This is in excess of the minimum
braking distance for wet pavements at 35 mph C 100 feet -
C:urve Y in Figure 1 ? . This design meets the cr i ter i a in
the f=ASHTO design manual and can be accommodated at the
proposed right-in/right-out Harmony Road access.
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100,/
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p 100Q0°0200 300 400 500 600
DISTANCE TRAVELED IFT)
DECELERATION DISTANCES
FOR PASSENGER VEHICLES
APPROACHING INTERSECTIONS
SPEED REACHED
(COMFORTABLE RATE)
A = 50 MPH
B = 40 MPII
C 30 MPH
D 20 MPH
E 0 MPH
MINIMUM BRAKING DISTANCE
X - DRYPAVEMENt
Y - WETPAVEMENT
FIGURE 1