Carter Addn 3-CS110106Page 1 of 2
George Marshall - RE: Carter Addition PhIII
From: "Casey Ross" <cross daa- civil com>
To: "George Marshall" <gmarshall(�'.&oppelltx.gov>
Date: 1/6/2011 9:42 AM
Subject: RE: Carter Addition PhIII
Attachments: AASHTO.pdf
George,
I would like to design the vertical curves to a speed limit of 25 MPH Attached is the latest AASHTO
requirements for the "K" values on crest and sag vertical curves. The "K" for a 25 MPH crest is 12 and the "K"
for a 25 MPH sag is 26. 1 will use a minimum 100' vertical curve length regardless of the "K" value. Please let
me know if I can design the vertical curves per AASHTO for a 25 MPH design speed.
Thanks,
Casey Ross, P.E., CFM
Dowdey, Anderson & Assoc.
5225 Village Creek Drive, Suite 200
Plano, TX 75093
972 - 931 -0694 (0)
469 -576 -1039 (C)
972 - 931 -9538 (F)
From: George Marshall [ mailto:gmarshall @coppelltx.gov]
Sent: Thursday, January 06, 20118:09 AM
To: Casey Ross
Subject: RE: Carter Addition PhIII
Please follow our subdivision regulations. See page 63 of our subdivision ordinance that covers geometric design
standards. Also note the minimum length of a vertical curve is 100'. Carter Edition Phase 1 was built under a
different set of design standards. You are expected to follow the current standards. Typically our street
department reviews the plans and then prepares a cost for signage and then bills the developer for the City to
install. Under rare instances the HOA /developer will enter into a licence agreement for them to install
and maintain the signs.
Thank You, George
George Marshall, PE
City of Coppell
Engineering
972 - 304 -3562
> > > "Casey Ross" < cross@daa- civil.com 1/5/20115:24 PM > > >
George,
I have another question for you. Carter Drive and Christi Lane have posted speed limit signs of 15 MPH. As I
begin design of Phase III, 1 would like to use "K" values in vertical curves that coincide with a design speed of 20
MPH. I will place 15 MPH signs in the design plans for Phase III. Is that acceptable?
file: HC: \Documents and Settings \radloo \Local Settings\ Temp \XPgrpwise \4D258EA2City_... 1/11/2011
Page 2 of 2
Thanks,
Casey Ross, P.E., CFM
Dowdey, Anderson & Assoc.
5225 Village Creek Drive, Suite 200
Plano, TX 75093
972 - 931 -0694 (0)
469 -576 -1039 (C)
972 - 931 -9538 (F)
From: George Marshall [ mailto:gmarshall @coppelltx.gov]
Sent: Tuesday, January 04, 20112:25 PM
To: Casey Ross
Subject: Re: Carter Addition PhIII
Casey,
As discussed earlier, our main concern is fire protection. You should perform a water analysis to determine if
there is sufficient pressure and flow for the proposed subdivision. If the water is sufficient then we will not
require a loop to Rolling Hills. A valve will need to be placed on the existing 6" between the two new roads.
Thank You, George
George Marshall, PE
City of Coppell
Engineering
972 - 304 -3562
> > > "Casey Ross" < cross@daa- civil.com 1/4/201111:54 AM > > >
George,
Attached is our most current land plan. With this layout, we won't have any dead -end water lines. We can
loop it internally within the subdivision and tie into the existing 6" in Carter Drive. With this layout, will we
need to acquire any offsite water easements?
Thanks,
Casey Ross, P.E., CFM
Dowdey, Anderson & Assoc.
5225 Village Creek Drive, Suite 200
Plano, TX 75093
972 - 931 -0694 (0)
469 -576 -1039 (C)
972 - 931 -9538 (F)
file: HC: \Documents and Settings \radloo \Local Settings\ Temp \XPgrpwise \4D258EA2City_... 1/11/2011
AAS'HT®— Geometric Design of Highways and Streets
a Rate of vertical curvature, K, is the length of curve per percent algebraic difference in
intersecting grades (A). K = LlA
Exhibit 3-72. Design Controls for Stopping Sight Distance and for Crest Vertical Curves
M etric
US Customa
Stopping
Rate of vertiF
Mopping
Rate of vertical
Design
sight
curvature,
sight
curvature, K
speed
distance
Design speed
Passing sight
curvature, K'
distance
distance (
(km /h)
m
Calculated
Dft
200
46
Calculated
Design
20
20
0.6
84
25
80
3.0
3
30
35
1.9
1090
424
115
6.1
7
40
50
3.8
70
485
155
11.1
12
50
65
6.4
338
45
200
18.5
19
60
85
11.0
11
35
250
29.0
29
70
105
16.8
17
40
305
43.1
44
80
130
25.7
26
45
360
60.1
61
90
160
38.9
39
50
425
83.7
84
100
185
52.0
52
55
495
113.5
114
110
220
73.6
74
60
570
150.6
151
120
250
95.0
95
65
645
192.8
193
130
285
123.4
124
70
730
246.9
247
75
820
311.6
312
80
910
383.7
384
a Rate of vertical curvature, K, is the length of curve per percent algebraic difference in
intersecting grades (A). K = LlA
Exhibit 3-72. Design Controls for Stopping Sight Distance and for Crest Vertical Curves
Note: *Rate of vertical curvature, K, is the length of curve per percent algebraic airrerence rn
intersecting grades (A). K = LlA
Exhibit 3 -73• Design Controls for Crest Vertical Curves Based. on Passing Sight Distance
Generally, it is impractical to design crest vertical curves to provide for passing sight
distance because of high cost where crest cuts are involved and the difficulty of fitting the
resulting long vertical curves to the terrain, particularly for high -speed roads. Passing sight
272
Metric
US custorrma
Rate of
=curvature,
vertical
Design speed
Passing si*
Design speed
Passing sight
curvature, K'
(km /h)
distance (
(mph)
distance (ft)
desi n
30
200
46
20
710
180
40
270
84
25
900
289
50
345
138
30
1090
424
60
410
195
35
1280
585
70
485
272
40
1470
772
80
540
338
45
1625
943
90
615
438
50
1835
1203
100
670
520
55
1985
1407
110
730
617
60
2135
1628
120
775
695
65
2285
1865
130
815
769
70
2480
2197
75
2580
2377
80
2680
2565
Note: *Rate of vertical curvature, K, is the length of curve per percent algebraic airrerence rn
intersecting grades (A). K = LlA
Exhibit 3 -73• Design Controls for Crest Vertical Curves Based. on Passing Sight Distance
Generally, it is impractical to design crest vertical curves to provide for passing sight
distance because of high cost where crest cuts are involved and the difficulty of fitting the
resulting long vertical curves to the terrain, particularly for high -speed roads. Passing sight
272
Elemen*ofDesign
Rate of vertical curvature, K,is the length of curve (m) per percent algebraic difference
Exhibit 3-75. Design C*atrols for Sag Vertical Curves
Sight distance on the highway through omude separation should b*at least as long as the
minimum stoppi sight distance and preferably longer. Tloabro of the vertical alignment is the
nuue no at any other point on the biohvvm/ except in some cuacw of sag vertical cnzvoa
underpassi a structure as illustrated in Exhibit 3-76. While not a frequent problem, the structure
fascia may cut the line of sight and limi the sight distance to less that otherwise is attainable. It is
genera practical to provide the minimum length of sag vertical curve discussed above at grade
separat ubooturom, and even where the recommended grades are exceeded, the sight distance
should not 000d to be reduced hdmw the minimum recommended values for stopping sight
For some conditions, t designer may wish to check the available sight distance atuu
«udororoa i ' such as at a two-lane unJozcroo i vv�bout ramps vrbere d would bu desirable to
provide passi sight distance. Such checks are best ruudo graphically ou the profile, but may ho
performed through computations.
Metric
US CU2!2M2g
Stopping
Stopping
Design
sight
Rate of vertical
Design
sight
Rate of vertical
speed
distance
curvature, K'
speed
distance
curvature, K
if
50
65
12.2
13
30
200
36.4
37
60
85
17.3
18
35
250
49.0
49
70
105
22.6
23
40
305
63A
64
80
130
29A
30
45
360
78.1
79
90
160
37.6
38
50
425
95.7
96
100
185
44.6
45
55
495
114.9
115
110
220
54.4
55
60
570
135.7
136
120
250
62.8
63
65
645
156.5
157
130
285
72.7
73
70
730
180.3
181
75
820
205.6
206
1 80
910
231.0
ZL—i
Rate of vertical curvature, K,is the length of curve (m) per percent algebraic difference
Exhibit 3-75. Design C*atrols for Sag Vertical Curves
Sight distance on the highway through omude separation should b*at least as long as the
minimum stoppi sight distance and preferably longer. Tloabro of the vertical alignment is the
nuue no at any other point on the biohvvm/ except in some cuacw of sag vertical cnzvoa
underpassi a structure as illustrated in Exhibit 3-76. While not a frequent problem, the structure
fascia may cut the line of sight and limi the sight distance to less that otherwise is attainable. It is
genera practical to provide the minimum length of sag vertical curve discussed above at grade
separat ubooturom, and even where the recommended grades are exceeded, the sight distance
should not 000d to be reduced hdmw the minimum recommended values for stopping sight
For some conditions, t designer may wish to check the available sight distance atuu
«udororoa i ' such as at a two-lane unJozcroo i vv�bout ramps vrbere d would bu desirable to
provide passi sight distance. Such checks are best ruudo graphically ou the profile, but may ho
performed through computations.