HomeMy WebLinkAboutLIBERTY FARMS - FDP - 31-06A/B - SUBMITTAL DOCUMENTS - ROUND 1 - TRAFFIC STUDYTruck Apron
A 12' truck apron is provided on the outside of the central island. The truck apron needs to
be designed with a mountable curb and structurally sound to accommodate the WB-67
trailer.
Sight Triangles
No landscape plan was provided at this time for review and analysis. However, sight
triangles should be maintained in accordance with Figures 6.29-32 of the informational
guide.
Conclusion
The roundabout design meets the design requirements of the information guide and the
LUCASS. Acceptable levels of service (LOS A) with minimum queues can be expected in
the long-range future. The roundabouts should operate safely and efficiently well into the
future if constructed as designed. The design volumes for the intersection are relatively
low and the intersection will operate acceptably and safely in the future.
ELB Engineering, LLC
5401 Taylor Lane
Fort Collins, CO 80528
Phone: 970-988-7551 1 FAX..- 970-225-8942
ELBEngineering@lpbroadband.net
M
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I 15:1:13 Liberty Farm Roundabout Analysis 10 1
I I
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I I I
1 E (m) 4.90 4.90 4.90 4.90 1 TIME PERIOD min 90
I L' (m) 10.00 10.00 10.00 10.00 1 TIME SLICE min 15 1
I V (m) 3.00 3.00 3.00 3.00 1 RESULTS PERIOD min 15 75 1
I RAD (m) 20.00 20.00 20.00 15.00 1 TIME COST $/hr 15.00 1
1 PHI (d) 26.00 30.00 26.00 30.00 1 FLOW PERIOD min 15 75 1
I DIA (m) 36.60 36.60 36.60 36.60 1 FLOW TYPE pcu/veh VEH I
I GRAD SEP 0 0 0 0 1 FLOW PEAK am/op/pm PM I
I________---------------
__________________________-_______
I LEG NAME IPCU I TURNS (1st exit, 2nd..U) IFLOFICLI FLOW RATIO IFLOW TIMEI
I I I I I I I I
I LEG1 11.051 10 5 40 0 11.5018010.75 1.125 0.75115 45 75 1
1 LEG2 11.051 5 95 5 0 11.5018010.75 1.125 0.75115 45 75 1
1 LEG3 11.051 75 5 5 0 11.5018010.75 1.125 0.75115 45 75 1
1 LEG4 11.051 25 155 130 0 11.5018010.75 1.125 0.75115 45 75 1
I I I I I I I I
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I I I I I I I I
I I I I I I
I I I
I FLOW veh 83 158 128 465 1 AVEDEL s 5.6 1
I CAPACITY veh 815 898 943 1014 I LOS SIG A I
I AVE DELAY secs 4.8 4.8 4.3 6.4 1 LOS UNSIG A I
I MAX DELAY secs 6.3 6.2 5.6 8.7 1 1
1 AVE QUEUE veh 0 0 0 1 1 VEHIC HRS 1.3 1
1 MAX QUEUE veh 0 0 0 1 1 COST $ 20 1
1-------------------------------------------------------------------------------
Other Design Parameters
Splitter Islands
Splitter islands are provided on all of the approaches to the intersection and provide
pedestrian refuge approximately 25' back from the yield line. The splitter islands are also
providing the necessary deflection required to achieve good operation. Each splitter island
is approximately 40' long and the yield lines should be set to standard.
ELB Engineering, LLC
5401 Taylor Lane
Fort Collins, CO80528
Phone: 970-988-7551 1 FAX 970-225-8942
ELBEngineering@lpbroadband.net
W
Capacity Analysis
Projected traffic volumes were determined by the analyses contained in Liberty Farms
Transportation Impact Study.
The design process utilized the 20-year volumes to provide a conservative analysis. The
roundabout was analyzed using the software program of RODEL as required by the
LCUASS. The results indicated that the future volumes could function under acceptable
levels of service (LOS A) as a single -lane urban roundabout. The RODEL capacity
reports are shown below
15:1:13
I E (m) 4.90
I L' (m) 10.00
I V (m) 3.00
I RAD (m) 20.00
I PHI (d) 26.00
I DIA (m) 36.60
1 GRAD SEP 0
I -------------------
Liberty Farm Roundabout Analysis
4.90
4.90
4.90
10.00
10.00
10.00
3.00
3.00
3.00
20.00
20.00
15.00
30.00
26.00
30.00
36.60
36.60
36.60
0
0
0
I
I LEG NAME IPCU I TURNS (1st exit, 2nd..U)
I I I
I LEG1 11.051 5
1 LEG2 11.051 5
1 LEG3 11.051 115
1 LEG4 11.051 15
I I I
---------------------
I I I
I
I
I FLOW veh
I CAPACITY veh
I AVE DELAY secs
I MAX DELAY secs
I AVE QUEUE veh
I MAX QUEUE veh
----------------------
5 15 0
130 10 0
5 5 0
50 40 0
I
------------------
I
TIME PERIOD min 90 1
TIME SLICE min 15 1
RESULTS PERIOD min 15 75 1
TIME COST $/hr 15.00 1
FLOW PERIOD min 15 75 1
FLOW TYPE pcu/veh VEH I
FLOW PEAK am/op/pm AM I
I
----------------------------------I
IFLOFICLI FLOW RATIO IFLOW TIMEI
11.5018010.75 1.125 0.75115 45 75 1
11.5018010.75 1.125 0.75115 45 75 1
11.5018010.75 1.125 0.75115 45 75 1
11.5018010.75 1.125 0.75115 45 75 1
I I I I
I I I I I
I I I I I
38
218
188
158
981
995
930
1010
3.7
4.5
4.7
4.1
4.7
5.8
6.2
5.3
0
0
0
0
0
0
0
0
--------------------I
I I
AVEDEL s 4.4
LOS SIG A I
I LOS UNSIG A I
I I
I VEHIC HRS 0.7 I
1 COST $ 11 I
I I
ELB Engineering, LLC 4
5401 Taylor Lane
Fort Collins, CO 80528
Phone: 970-988-7551 1 FAX. 970-225-8942
ELBEngineering@lpbroadband.net
Table 1
Fastest Path Calculations
NB Approach
Radius ID
radius feet
Velocity
(mph)
R1
68
16.90
R2
78
18.10
R3
83
18.67
R4
53
14.92
R5
65
16.52
WB Approach
Radius ID
radius feet
Velocity
(mph)
R1
70
17.15
R2
50
.
14.49
R3
91
19.55
R4
53
14.92
R5
93
19.76
SB Approach
Radius ID
radius feet
Velocity
(mph)
R1
119
22.36
R2
53
14.92
R3
53
14.92
R4
53
14.92
R5
153
25.35
EB Approach
Radius ID
radius feet
Velocity
(mph)
R1
54
15.06
R2
55
15.20
R3
72
17.39
R4
53
14.92
R5
43
13.44
All of the fastest path calculations reveal that the roundabout will provide a reasonable and
safe operating speed.
ELB Engineering, LLC
5401 Taylor Lane
Fort Collins, CO 80518
Phone: 970-988-7551 1 FAX. 970-115-8941
ELBEngineering@Ipbroadband. net
The design of the roundabout utilized the following documents as guidance:
• LCUASS-2002
• Roundabout Information Guide, Federal Highway Administration, June
2000.
Fastest Path Calculations
Designs speeds were calculated for each of the approaches. The radii identification for
each movement is shown in the figure below. The following table shows the fastest path
radiuses for the roundabout designs. These paths were constructed using the methodology
as described in the FFIWA roundabout Information Guide, Chapter 6.
rigure 2: Modem Roundabout Radius ldentiAication
Source: FHWA Roundabouts: Informational Guide
ELB Engineering. LLC
5401 Taylor Lane
Forr Collins. CO 80528
Phone: 970-988.7551 1 PAX' 970-225-8942
ELBEngineeringQlpbroadband.ner
���IIIeellll� LLC
Transporietioa Eagiaeering.Solutions
Memorandum
TO: Mr. Ward Stanf6rd, Traffic Engineer
W. Don Tiller
FROM: Eric L. Bracke, P.E., P.T.O.E
DATE: February 5, 2008
SUBJECT: Liberty Farm Roundabout Design Review
This memorandum addresses the supplemental information requested by the City of Fort
Collins Traffic Operations Department regarding the design of the modem roundabout
being proposed at the intersection of Cherry Hurst Road and Collamer Road in the Liberty
Farms Development.
The proposed modern roundabout is a 4-legged roundabout with an inscribed diameter of
120 feet. The west leg and north leg of the roundabout are classified as minor arterials and
the south leg and east leg are classified as collector/connector roadways. The roundabout
is shown below.
Figure I : Cherry6uraVCohmer Modem Roundabout
£L8 Engineering, LLC
5401 Taylor Lane
Fort Collins, CO 80528
Phone: 970-988-7551 1 FAX 970-225-8942
ELBEngineenng@Ipbroadband.net