INTRODUCTION This memorandum presents the results ... - Arlingtonva
SP #
Re:
Site Development
Subject:
Preliminary Parking Management and Garage Plan Sample Queuing Analysis
—
Date:
INTRODUCTION This memorandum presents the results of a queuing analysis for the inbound traffic at the garage access of the approved academic/office building as part of Site Plan #. The purpose of this assessment is to respond to a request from Arlington County for an evaluation of the queuing from inbound traffic at the proposed academic/office building garage entrance, to ensure that queues will remain within the subject property without extending on to the public roadway network.
ANALYSIS The following assumptions and calculations were made to perform the queuing analysis: 1. The number of inbound lanes at the academic/office building garage entrance was two (2) during the AM peak hour, and one (1) during the PM peak hour. 2. Office employees and students were assumed to use a proximity card for transient”/retail users and visitors were assumed to t entry into the garage; ‘ use a pay-on-foot system for entry into the garage. 3. Peak hour forecasts for the academic/office building garage entrance were
obtained from the traffic impact analysis. For purposes of this analysis, “monthly” users were considered to include office and academic uses, and “transient” users were considered to include retail uses.
= 257 vehicles/ho ur 111 vehicles/hour
AM Peak Hour Inbound Monthly Users Volume (Vm) PM PeakHour Inbound Monthly Users Volume (I/rn)
=
AM Peak Hour Inbound Transient Users Volume (Vt) PM Peak Hour Inbound Transient Users Volume (Vt)
= 3 vehicles/hour = 4 vehicles/hour
TotalAM Peak Hour Inbound Monthly Users Volume (I/rn) = 260 vehicles/hour Total PM Peak Hour Inbound Monthly Users Volume (Vrn) = 115 vehicles/hour Lane processing rates for each of the uses were derived from PARC service rates established in the Parking Structures, Third Edition manual. A blended processing rate was then derived. Monthly Users (Office and Academic) Processing Rate sec/vehicle) Transient Users (Retail) Processing Rate (,Ut) sec/vehicle)
=
yin
+ +
[LAM
[IPM
=
257 vph 257 vph/( 00 vph
+ +
=
lllvph 111 vph/1600 vph
=
= 400 vphpl (or 9
3vph (3 vph./ 00 vph)
597 vph (or 6.03 sec/vehicle)
+
600 vphpl (or 6
Vt V/ji
=
+
(trn)=
4vph (4 vph/(400 vph)
590 vph (or 6.10 sec/vehicle)
For a more conservative analysis, a turn factor was added into the lane processing rates to account for the time required for vehicles to turn into the gate area. A turn factor of approximately 1 seconds/vehicle was applied.
The total service rate
(ji)
Total Service Rote (iU1M)
for the gate is as follows: = =
Total Service Rate (PMJ
= =
2 lanes * 3600/(6.03 sec/vehicle 1,024 vehicles/hour 1 lane *3600/(6lOsec/vellicle 507 vehicles/hour
+
+
1 sec/vehicle)
1 sec/vehicle)
The traffic intensity (A) is generally A Thus, the traffic intensity for each gate is as follows: AM Peak Hour Traffic Intensity (2am) =
PM Peak Hour Traffic Intensity (Aprn)
=
=
260/1,024 0254 115/507 0.227
Attachment I shows the Parking Structures, Third Edition design queue curve as a function of traffic intensity. It is inferred from the graph that the 90% probability queue for the entrance, as a two4ane gate, would be zero (0) vehicles in the reservoir during the AM peak hour and zero (0) vehicles in the reservoir during the PM peak hour.
CONCLUSION As shown in the analysis elaborated above, allowing for two inbound lanes during the AM peak hour and one inbound lane during the PM peak hour would minimize queuing at the academic/office building entrance.
Attachment I
Design Queues 90% Probabhty
30
28
E
28
-_
24
4_
22 20 UI 18
14 12
z z
z
z z
z
z
10
8 71
4 I
2 0
*4* 0.00
*ê1 44I1 0.20 0.10
0,30
0.40
‘:r:: rirz 13.70
Tratfic lntonsfty j-*-i Ln e 2 Lanes ——3 Lone
4L8nes ——5Lan ——6Lano8
Figure 442. Design queue curves
Entrance AM Traffic Intensity of 0.254 along “2 Lanes” curve 90% Probability Queue (Reservoir Behind Service Position) =0 Vehicles Entrance PM Traffic Intensity of 0.227 along “2 Lanes” curve 90% Probability Queue (Reservoir Behind Service Position) =0 Vehicles
0.80
0,00
100
Non-Auto Mode Shore Reduction Retail Subtotal
Non-Auto Mode Shore Reduction Office Subtotal
Residential Subtotal
Non-Auto Mode Shore Reduction
-
826
710
220
272
105,000
80%
5,000
35%
55,000
50%
Square Feet
Square Feet
Square Feet
Dwelling Units
Square Feet
273 147
189
13 3
16
37 68
105
13
27 14
97 78
29
18 14 4
5 9
14
55
110 55
19
Out
AM Peak Hour
370 225
218
27 7
34
42 77
119
68
137 69
145
Total
Therefore, this ratio of 1.5 was multiplied with the existing trip generation to derive the proposed trip generation.
141 For the AM peak hour, a peak hour of the generator rate was used due to the lack of ITE data for peak hour of the adjacent Street. (51 Trip generation of proposed academic uses estimated based on the square footage ratio of the existing trip generation (see note 2.) The
(3) Average daily trips generated for academic uses estimated as ten 110) times the observed PM peak hour traffic.
63
In
169 106
95
15 11 4
ratio of 105,000 S.F. to 70,000 S.F. is 1.5.
182 132
75
18 15 3
75 16
8
116 41
29
58 29
50
Out
PM Peak Hour
24
109 55 54
(21 Existing trip generation for academic uses based on existing driveway counts for the peak hour of the adjacent Street at the intertection of N. Fairfax Drive and N. Glebe Road.
(1) Trip generation calculations based on Institute of Transportation Engineers lITEl Trip Generation, Ninth Edition.
Notes:
Total Proposed Net-New Trips
Academic (3)(5)
Retail (4)
Building Two Office
Residential
Proposed Uses Building One
70000 126
-
Units
Academic (2)(3)
Quantity In
ITE Land Use Code
Development Existing Uses
-
Site Plan Development SP If Site Trip Generation Summary (1)
351 238
170
33 26 7
49 91
140
83
167 84
113
Total
ADT
3171 2041
1700
222 178 44
292 541
833
1772 886 886
1130
Total
Re:
Site Development
Subject:
Preliminary Parking Management and Garage Plan Sample Queuing Analysis
—
Date:
INTRODUCTION This memorandum presents the results of a queuing analysis for the inbound traffic at the garage access of the approved academic/office building as part of Site Plan #. The purpose of this assessment is to respond to a request from Arlington County for an evaluation of the queuing from inbound traffic at the proposed academic/office building garage entrance, to ensure that queues will remain within the subject property without extending on to the public roadway network.
ANALYSIS The following assumptions and calculations were made to perform the queuing analysis: 1. The number of inbound lanes at the academic/office building garage entrance was two (2) during the AM peak hour, and one (1) during the PM peak hour. 2. Office employees and students were assumed to use a proximity card for transient”/retail users and visitors were assumed to t entry into the garage; ‘ use a pay-on-foot system for entry into the garage. 3. Peak hour forecasts for the academic/office building garage entrance were
obtained from the traffic impact analysis. For purposes of this analysis, “monthly” users were considered to include office and academic uses, and “transient” users were considered to include retail uses.
= 257 vehicles/ho ur 111 vehicles/hour
AM Peak Hour Inbound Monthly Users Volume (Vm) PM PeakHour Inbound Monthly Users Volume (I/rn)
=
AM Peak Hour Inbound Transient Users Volume (Vt) PM Peak Hour Inbound Transient Users Volume (Vt)
= 3 vehicles/hour = 4 vehicles/hour
TotalAM Peak Hour Inbound Monthly Users Volume (I/rn) = 260 vehicles/hour Total PM Peak Hour Inbound Monthly Users Volume (Vrn) = 115 vehicles/hour Lane processing rates for each of the uses were derived from PARC service rates established in the Parking Structures, Third Edition manual. A blended processing rate was then derived. Monthly Users (Office and Academic) Processing Rate sec/vehicle) Transient Users (Retail) Processing Rate (,Ut) sec/vehicle)
=
yin
+ +
[LAM
[IPM
=
257 vph 257 vph/( 00 vph
+ +
=
lllvph 111 vph/1600 vph
=
= 400 vphpl (or 9
3vph (3 vph./ 00 vph)
597 vph (or 6.03 sec/vehicle)
+
600 vphpl (or 6
Vt V/ji
=
+
(trn)=
4vph (4 vph/(400 vph)
590 vph (or 6.10 sec/vehicle)
For a more conservative analysis, a turn factor was added into the lane processing rates to account for the time required for vehicles to turn into the gate area. A turn factor of approximately 1 seconds/vehicle was applied.
The total service rate
(ji)
Total Service Rote (iU1M)
for the gate is as follows: = =
Total Service Rate (PMJ
= =
2 lanes * 3600/(6.03 sec/vehicle 1,024 vehicles/hour 1 lane *3600/(6lOsec/vellicle 507 vehicles/hour
+
+
1 sec/vehicle)
1 sec/vehicle)
The traffic intensity (A) is generally A Thus, the traffic intensity for each gate is as follows: AM Peak Hour Traffic Intensity (2am) =
PM Peak Hour Traffic Intensity (Aprn)
=
=
260/1,024 0254 115/507 0.227
Attachment I shows the Parking Structures, Third Edition design queue curve as a function of traffic intensity. It is inferred from the graph that the 90% probability queue for the entrance, as a two4ane gate, would be zero (0) vehicles in the reservoir during the AM peak hour and zero (0) vehicles in the reservoir during the PM peak hour.
CONCLUSION As shown in the analysis elaborated above, allowing for two inbound lanes during the AM peak hour and one inbound lane during the PM peak hour would minimize queuing at the academic/office building entrance.
Attachment I
Design Queues 90% Probabhty
30
28
E
28
-_
24
4_
22 20 UI 18
14 12
z z
z
z z
z
z
10
8 71
4 I
2 0
*4* 0.00
*ê1 44I1 0.20 0.10
0,30
0.40
‘:r:: rirz 13.70
Tratfic lntonsfty j-*-i Ln e 2 Lanes ——3 Lone
4L8nes ——5Lan ——6Lano8
Figure 442. Design queue curves
Entrance AM Traffic Intensity of 0.254 along “2 Lanes” curve 90% Probability Queue (Reservoir Behind Service Position) =0 Vehicles Entrance PM Traffic Intensity of 0.227 along “2 Lanes” curve 90% Probability Queue (Reservoir Behind Service Position) =0 Vehicles
0.80
0,00
100
Non-Auto Mode Shore Reduction Retail Subtotal
Non-Auto Mode Shore Reduction Office Subtotal
Residential Subtotal
Non-Auto Mode Shore Reduction
-
826
710
220
272
105,000
80%
5,000
35%
55,000
50%
Square Feet
Square Feet
Square Feet
Dwelling Units
Square Feet
273 147
189
13 3
16
37 68
105
13
27 14
97 78
29
18 14 4
5 9
14
55
110 55
19
Out
AM Peak Hour
370 225
218
27 7
34
42 77
119
68
137 69
145
Total
Therefore, this ratio of 1.5 was multiplied with the existing trip generation to derive the proposed trip generation.
141 For the AM peak hour, a peak hour of the generator rate was used due to the lack of ITE data for peak hour of the adjacent Street. (51 Trip generation of proposed academic uses estimated based on the square footage ratio of the existing trip generation (see note 2.) The
(3) Average daily trips generated for academic uses estimated as ten 110) times the observed PM peak hour traffic.
63
In
169 106
95
15 11 4
ratio of 105,000 S.F. to 70,000 S.F. is 1.5.
182 132
75
18 15 3
75 16
8
116 41
29
58 29
50
Out
PM Peak Hour
24
109 55 54
(21 Existing trip generation for academic uses based on existing driveway counts for the peak hour of the adjacent Street at the intertection of N. Fairfax Drive and N. Glebe Road.
(1) Trip generation calculations based on Institute of Transportation Engineers lITEl Trip Generation, Ninth Edition.
Notes:
Total Proposed Net-New Trips
Academic (3)(5)
Retail (4)
Building Two Office
Residential
Proposed Uses Building One
70000 126
-
Units
Academic (2)(3)
Quantity In
ITE Land Use Code
Development Existing Uses
-
Site Plan Development SP If Site Trip Generation Summary (1)
351 238
170
33 26 7
49 91
140
83
167 84
113
Total
ADT
3171 2041
1700
222 178 44
292 541
833
1772 886 886
1130
Total
