Intro Theory and Calcs

1.0 Introduction1.1 Background and Context

The intersection at the University of the West Indies southern access way and the Churchill Roosevelt

Highway becomes very congested during peak hours. Congestion of the intersection affect students,

university employees and surrounding businesses. The congestion also delays traffic along the eastbound

and westbound lanes towards Port of Spain noted as the largest business center in Trinidad. Traffic

congestion is most often criticized as a waste of time and money, a cause of pollution and stress, and a

detriment to productivity (Bertini, 2005). It is in this context that a detailed analysis of the intersection be

undertaken to assess the current and future traffic patterns of the intersection and also to draw conclusions

about the efficiency and functionality of the intersection.

Aim

To study the intersection at the University of the West Indies southern access road and the Churchill

Roosevelt Highway, provide recommendations to improve the performance of the intersection and

evaluate the sustainability of the intersection in the year 2020 using an average annual traffic growth

rate of 4.0%.

Objective

The objectives of this traffic study are to:

1. Determine the flows and volumes passing through the intersection.2. Investigate the current behavior and trends of traffic passing through the intersection. 3. Determine the saturation flow rate of the intersection.4. Determine the Level of Service (LOS) of the intersection.5. Determine the capacity of the intersection6. Determine 3, 4 and 5 of the intersection in 2020 at a traffic growth rate of 4.0%

Scope

The study area for this study is confined only to the intersection is confined only to the intersection.

What vehicle did or where they went have little bearing on the study. Traffic counting was carried out in

two 3-hour sessions, 6:00 am–9:00 am and 3:00 pm-6:00pm. Manual Counting was the method used to

acquire data.

Theory

Volume of Traffic

The volume of traffic is defined as the total amount of traffic passing through a given point in a

specific direction within the specified period of time. By counting the number of vehicles that pass a

point on the roadway during a 15-minute period, you can arrive at the 15-minute volume. Volume is

commonly converted directly to flow, which is a more useful parameter.

Saturation Flow Rate

Saturation Flow rate of an intersection can be defined as the number of vehicles per hour that

could cross the line if the signal remained in a continuous green state. However it is not practical to

measure this quantity directly in the field because the signal will not normally remain green for the

required time. The saturation flow rate is typically derived from the steady-state headway. The headway

is defined as the average elapsed time between the passages of successive vehicles over the stop line in

the same lane. The Highway Capacity Manual (2010) states that the headway should be taken from the

passage of the fourth vehicle to the seventh, eighth, ninth or tenth vehicle. This method however

assumes that the queue length is at minimum ten vehicles.

Capacity of Intersection

The capacity of the intersection is defined as the maximum rate at which vehicles can pass

through an intersection in one hour under prevailing conditions. The capacity of the intersection

accounts for roadway conditions such as lane configurations, lane utilization and signalized conditions.

In order to calculate the Capacity of the Intersection, the effective green and the saturation flow rate are

also needed. The process for obtaining on the Saturation Flow rate is describe above. However the

effective green is measured as the time that is available to a designated movement, and generally taken

to be the green time plus the change and clearance interval minus the lost time for the designated

movement.

Level of Service (LOS)

The Highway Capacity Manual (HCM) defines the level of service of a signalized intersection as the total

delay of all movements through an intersection. Control delay is used to define the level of service at

signalized intersections, given delay not only indicates the amount of lost travel time and fuel

consumption but also a measure of the frustration and discomfort of motorists. Control or signal delay,

which is that portion of total delay that is attributed to the control facility, is computed to define the

level of service at the signalized intersection. This includes the delay due to the initial deceleration,

queue move-up time, stopped time, and final acceleration. Delay, however, depends on the red time,

which in turn depends on the length of the cycle (Garber & Hoel 2009, 460).

Cycle Length

Cycle length is composed of the total signal time to serve all of the signal phases including the green time

plus any change interval. Longer cycles will accommodate more vehicles per hour but that will also

produce higher average delays.

MethodologyFlow Chart Showing Methodology for Signalized Intersections

Chart 1 (Taken from the Highway Capacity Manual 2010, pg. 18-32)

Results and Calculations

MORNING 6:00AM-9:00AM

Table 1- Vehicular Traffic Morning

Time Period Northbound Southbound Eastbound Westbound Total No.LEFT Through Right LEFT Through Right LEFT Through Right LEFT Through Right

6.00 - 6.15 31 23 31 7 27 42 7 255 7 12 567 16 10256.15 -6.30 23 42 23 16 27 43 18 409 5 9 441 14 10706.30-6.45 33 55 33 8 51 56 34 307 5 7 480 16 10856.45-7.00 74 33 74 17 71 59 36 421 10 15 502 22 13347.00-7.15 28 70 28 15 62 71 47 370 8 11 521 66 12977.15-7.30 39 83 39 19 87 67 82 430 10 27 447 70 14007.30-7.45 35 61 35 19 72 63 70 444 15 43 489 112 14587.45-8.00 50 78 50 21 76 94 96 375 13 43 465 114 14758.00-8.15 46 79 46 23 64 90 97 482 7 72 454 115 15758.15-8.30 36 69 36 13 49 88 106 490 16 54 644 87 16888.30-8.45 34 74 34 19 58 89 126 387 10 39 614 113 15978.45-9.00 34 88 34 18 69 86 128 446 13 30 479 87 1512Total 463 755 463 195 713 848 847 4816 119 362 6103 832

Vehicular Traffic @ 6am - 9 am

Table 2- Northbound & Southbound Peak Hour Factor

Through Lane Through Lane15 min 60min 15 min 60min 15 min 60min 15min 60min 15 min 60min 15 min 60min

6.00 - 6.15 31 23 31 7 27 426.15 -6.30 23 42 23 16 27 436.30-6.45 33 55 33 8 51 566.45-7.00 74 74 33 153 74 161 17 48 71 176 59 2007.00-7.15 28 28 70 200 28 158 15 56 62 211 71 2297.15-7.30 39 39 83 241 39 174 19 59 87 271 67 2537.30-7.45 35 35 61 247 35 176 19 70 72 292 63 2607.45-8.00 50 50 78 292 50 152 21 74 76 297 94 2958.00-8.15 46 46 79 301 46 170 23 82 64 299 90 3148.15-8.30 36 36 69 287 36 13 76 49 261 88 3358.30-8.45 34 34 74 300 34 166 19 76 58 247 89 3618.45-9.00 34 34 88 310 34 150 18 73 69 240 86 353

Peak Hour FactorMax 15min 74 88 74 23 87 94Max 60min 74 310 176 82 299 361

Left Lane Right Lane Left Lane Right LaneNorthbound Southbound

Time Period

0.25 0.88 0.59 0.89 0.86 0.96

Table 3 - Eastbound & Westbound Peak Hour Factor

6.00 - 6.156.15 -6.306.30-6.456.45-7.007.00-7.157.15-7.307.30-7.457.45-8.008.00-8.158.15-8.308.30-8.458.45-9.00

Peak Hour FactorMax 15minMax 60min

Time PeriodThrough Lane Through Lane

15 min 60min 15 min 60min 15 min 60min 15 min 60min 15 min 60min 15 min 60min7 255 7 12 567 16

18 409 5 9 441 1434 307 5 7 480 1636 95 421 1392 10 27 15 43 502 1990 22 6847 135 370 1507 8 28 11 42 521 1944 66 11882 199 430 1528 10 33 27 60 447 1950 70 17470 235 444 1665 15 43 43 96 489 1959 112 27096 295 375 1619 13 46 43 124 465 1922 114 36297 345 482 1731 7 45 72 185 454 1855 115 411

106 369 490 1791 16 51 54 212 644 2052 87 428126 425 387 1734 10 46 39 208 614 2177 113 429128 457 446 1805 13 46 30 195 479 2191 87 402

128 490 16 72 644 115457 1805 51 212 2191 429

0.74 0.85 0.930.92

Left Lane Right LaneEastbound Westbound

0.85

Left Lane Right Lane

0.89

Table 4 - Northbound Saturation Flow Rate

7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh.

1 6 1 7

2 8 10 2 83 12 3 44 6 4 115 13 5 116 18 6 77 10 7 108 11 8 69 13 9 8

10 9 10 911 13 11 912 9 12 813 13 13 1014 8 14 1015 17 15 4

Total 41 31 50 54 Total 32 34 28 28

1336.082 veh/hr 1834.655 veh/hrSaturation Flow Rate Saturation Flow Rate

Through Lane Righ Turn

Time: 6 - 9 am

Obs. No.

Time (sec) between 4th vehicle and …

Obs. No.


SATURATION FLOW RATE NORTHBOUND

Bound Traffic: North

Lane(s): Through; Right Turn

Table 5- Southbound Saturation Flow Rate

15

Through Right-Turn

7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh.1 5 1 82 8 2 73 11 3 104 13 4 115 9 5 156 11 6 77 5 7 128 7 8 109 8 9 8

10 5 10 911 8 11 612 9 12 713 8 13 1414 9 14 615 11 15 7

Total 23 32 37 35 Total 33 23 33 48

1869 veh/hr 1722.488 veh/hr

SATURATION FLOW RATE SOUTHBOUND

Total # of observations

Obs. No.Time (sec) between 4th vehicle and …


Saturation Flow Rate Saturation Flow Rate

Bound Traffic: South Lane(s): Through; Right TurnTime: 6 to 9 am

Table 6 - Eastbound Saturation Flow Rate

Lane 1 +2 Lane 3

7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh.1 9 1 122 9 2 19 123 9 3 9 134 9 4 85 10 5 86 13 6 117 17 7 118 9 8 79 11 9 11

10 13 10 1011 6 11 912 9 12 813 10 13 714 14 14 915 8 15 0 9

Total 14 65 37 40 Total 7 93 37 36

1543.592 veh/hr 1385.207 veh/hrX2 3087.184 veh/hr

Average Saturation Flow Rate 1490.797 veh/hr NO SAT FLOW FOR RIGHT TURNING LANE

SATURATION FLOW RATE EASTBOUND

Bound Traffic: EastLane(s): Through; Right Turn


Time: 6 to 9 am



Table 7- Westbound Saturation Flow Rate

Lane 1 +2 Lane 3 Turn Lane

7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh.1 6 1 9 1 62 12 2 12 2 93 9 3 13 3 84 5 4 7 4 85 10 5 8 5 76 7 6 9 6 117 11 7 8 7 128 10 8 8 8 79 8 9 7 9 6

10 13 10 10 10 1111 10 11 12 11 1012 9 12 5 12 913 8 13 6 13 1114 15 14 16 14 1215 11 15 6 15 5

Total 40 39 42 23 Total 31 33 19 53 Total 19 22 56 35

1529.023 veh/hr 1729.845 veh/hr 1870.67 veh/hrX2 3058.046 veh/hr

Average Saturation Flow Rate 1595.964 veh/hr

Time (sec) between 4th vehicle and …Obs. No.


Saturation Flow Rate Saturation Flow Rate Saturation Flow Rate

Time: 6 to 9 am


Obs. No.

Bound Traffic: WestLane(s): Through; Right Turn

SATURATION FLOW RATE WESTBOUND

Table 8 - Theoretical Saturation Flow Rate

Lane Width

fw

Heavy Vehicles

fHV

Grade fgParking

fp

Bus Blockage

fbb

Utilisation Factor

Area Type fa

Right Turn fRT

Left Turn fLT

Table 9-5 Table 9-6 Table 9-7 Table 9-8 Table 9-9 Table 9-4 Table 9-10 Table 9-11 Table 9-12

L 1900 1 1.00 0.98 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1863T 1900 1 1.00 0.95 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1810

R 1900 1 1.00 0.97 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1845

L 1900 1 1 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1889

T 1900 1 1.00 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1876R 1900 1 1.00 0.97 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1845L 1900 1 1.00 0.98 1 1 1 1 1 1 1 1862T 1900 3 1.00 0.94 1.00 0.95 1.00 0.91 1.00 1.00 1.00 4649R 1900 2 1.00 0.98 1.00 1.00 1.00 1.00 1.00 0.95 1.00 3550L 1900 1 1.00 0.95 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1805T 1900 3 1.00 0.97 1.00 0.95 1.00 0.91 1.00 1.00 1.00 4770R 1900 2 1.00 0.99 1.00 1.00 1.00 1.00 1.00 0.95 1.00 3581

Theoretical Saturation Flow Rate

Ideal Saturation Flow

No. of Lanes (N)

Adjustment FactorsAdjusted

Saturation Flow Rate, S

Movement

NB

SB

EB

WB

Table 9 - Calculation of Adjusted Flow Rate

L 74 0.25 296 1.00 296

T 310 0.88 352.272727 1.00 352.2727273

R 176 0.59 298.305085 1.00 298.3050847

L 82 0.89 92.1348315 1.00 92.13483146

T 299 0.86 347.674419 1.00 347.6744186

R 361 0.96 376.041667 1.00 376.0416667

L 457 0.89 513.483146 1.00 513.4831461

T 1805 0.92 1961.95652 0.91 1785.380435

R 51 0.85 60 1.00 60L 212 0.74 286.486486 1.00 286.4864865T 2191 0.85 2577.64706 0.91 2345.658824R 429 0.93 461.290323 1.00 461.2903226

NB

SB

EB

WB

Traffic Characteristics

Intersection MovementVolume in

veh/hrPeak Hour

Factor [PHF]

Adjusted Volume in

veh/hrLane Group

Lane Utilization

Factor [LUF]

Adjusted Flow Rate [v]

in veh/hr

Table 10 - Cycle Length

NorthBound SouthBoundThrough(s) Through(s) Through(s) Right (s) Through(s) Right (s)

194 194 188 191196 189 187 189

188 188 194Average 195 190.33 187.67 191.33Total Average 191.08

Traffic Light SignalsCycle Length

West Bound EastBound

Table 11- Phase Length

NorthBound SouthBound NorthBound SouthBoundThrough(s) Through(s) Through(s) Right (s) Through(s) Right (s) Through(s) Through(s) Through(s) Right (s) Through(s) Right (s)

25 34 76 9 100 20 3 3 5 6 5 925 34 76 9 100 20 3 3 5 6 5 925 34 76 9 20 3 3 5 6 9

Amber to Red EastBound West Bound

Traffic Light Signals

EastBound West Bound Green to Amber

Table 12 - Lane Capacity

L 296.0 N/A N/A 191 N/A N/A N/A N/AT 352.3 1336 25 191 0.131 174.80 2.015 0.264R 298.3 1834.65 25 191 0.131 240.03 1.243 0.163L 92.1 N/A N/A 191 N/A N/A N/A N/AT 347.7 1868.51 34 191 0.178 332.47 1.046 0.186R 376.0 1722.49 34 191 0.178 306.49 1.227 0.218L 513.5 N/A N/A 191 N/A N/A N/A N/AT 1785.4 1490.80 76 191 0.398 592.94 3.011 1.198R 60.0 N/A 9 191 0.047 N/A N/A N/AL 286.5 N/A N/A 191 N/A N/A N/A N/AT 2345.7 1595.96 100 191 0.523 835.22 2.808 1.470R 461.3 1870.66975 20 191 0.105 195.80 2.356 0.247

EB

WB

Capactiy

Effective green [g/C]

Lane Group Capacity [c] in

Lane Group Ratio [X=v/c]

Flow Ratio = v/s

NB

SB

Intersection MovementAdj. Flow Rate [v] in

Saturation Flow Rate [s]

Green Time [g] in sec

Cycle [C] in sec

Table 13 - Level of Service

k 0.5 T 0.25 I 1 Cycle length 191

L 296.0 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 352.3 0.131 2.015 174.80 0.33 0.043 1.0 1.101 2.015 41.189 45.3427 FR 298.3 0.131 1.243 240.03 0.33 0.043 1.0 1.101 1.243 66.791 73.52699 FL 92.1 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 347.7 0.178 1.046 332.47 0.33 0.059 1.0 1.145 1.046 75.074 85.9612 FR 376.0 0.178 1.227 306.49 0.33 0.059 1.0 1.145 1.227 63.986 73.26551 FL 513.5 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 1785.4 0.398 3.011 592.94 0.33 0.131 1.0 1.442 3.011 19.102 27.55345 FR 60.0 0.047 N/A N/A 0.33 0.016 1.0 1.033 N/A N/A N/A N/AL 286.5 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 2345.7 0.523 2.808 835.22 0.33 0.173 1.0 1.736 2.808 16.209 28.13209 FR 461.3 0.105 2.356 195.80 0.33 0.035 1.0 1.078 2.356 36.293 39.13521 F

Intersection

Level Of Service

EB 27.55 C

WB 29.94 C

LOS by Approach

NB 58.27 E

SB 79.36 E

d1 in s/veh

d in s/veh

LOS by Lane

Group Ratio

Delay by Approach in s/veh

Lane Group Capacity [c] in veh/hr

Rp [Arrival Type 1]

P = Rp x (g/C)fp [Assumed Arrival Type

1]

PF = (1-P)fp/(1-[g/C])


Lane Group Ratio

[X=v/c]

Effective Green [g/C]

Adjusted Flow Rate

[v] in veh/hrMovement

Table 14 - Projected Growth Rate

L 5 0.04 N/A N/A N/A N/A N/AT 2 0.04 1336.08247 1445.11 0.131 174.80 189.07R 2 0.04 1834.65459 1984.36 0.131 240.03 259.62L 2 0.04 N/A N/A N/A N/A N/AT 2 0.04 1868.51211 2020.98 0.178 332.47 359.60R 2 0.04 1722.48804 1863.04 0.178 306.49 331.50L 2 0.04 N/A N/A N/A N/A N/AT 2 0.04 1490.79724 1612.45 0.398 592.94 641.32R 2 0.04 N/A N/A N/A N/A N/AL 2 0.04 N/A N/A N/A N/A N/AT 2 0.04 1595.96381 1726.19 0.523 835.22 903.37R 2 0.04 1870.66975 1870.6697 0.105 195.80 195.80

WB 29.94 32.38 C

NB 58.27 70.89 E

SB 79.36 85.84 F

EB 27.55 29.80 C

Projected Growth Rate for the year 2020Assumed

Unchanged Effective

Lane Group Capacity [c] 2015

in veh/hr

Projected Lane Group Capacity [c]

Delay by Approach 2015

in s/veh

Projected Delay by

Approach LOSIntersection Movement

# of years of prediction

traffic growth rate/r

Saturation Flow Rate 2015 [s] in

Projected Saturation Flow Rate

EVENING 3:00PM-6:00PM

Table 15- Vehicular Traffic Evening

LEFT THROUGH RIGHT LEFT THROUGH RIGHT LEFT THROUGH RIGHT LEFT THROUGH LEFT6:00-6:15 9 42 20 16 51 131 96 581 37 62 505 65 16156:15-6:30 8 39 43 5 56 145 79 580 18 27 432 67 14996:30-6:45 5 41 27 11 51 105 87 618 32 27 476 53 15336:45-7:00 6 58 33 16 61 131 120 552 23 14 380 65 14597:00-7:15 11 58 29 20 38 119 103 675 31 32 528 55 16997:15-7:30 6 45 25 16 58 148 97 489 26 42 440 67 14597:30-7:45 8 69 30 8 38 129 120 656 23 46 575 52 17547:45-8:00 6 46 23 13 50 149 90 480 14 20 398 70 13598:00-8:15 12 50 22 16 41 120 94 613 15 22 573 60 16388:15-8:30 9 50 29 28 45 129 77 504 19 19 389 56 13548:30-8:45 8 56 34 21 53 119 93 563 12 14 521 53 15478:45-9:00 11 57 39 8 29 88 76 594 17 29 445 51 1444

Total 99 611 354 178 571 1513 1132 6905 267 354 5662 714

Total No.Time PeriodNorthbound Southbound Eastbound Westbound

Vehicular Traffic @3pm-6pm

Table 16 - Northbound & Southbound Peak Hour Factor

15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min6:00-6:15 9 42 20 16 51 1316:15-6:30 8 39 43 5 56 1456:30-6:45 5 41 27 11 51 1056:45-7:00 6 28 58 180 33 123 16 48 61 219 131 5127:00-7:15 11 30 58 196 29 132 20 52 38 206 119 5007:15-7:30 6 28 45 202 25 114 16 63 58 208 148 5037:30-7:45 8 31 69 230 30 117 8 60 38 195 129 5277:45-8:00 6 31 46 218 23 107 13 57 50 184 149 5458:00-8:15 12 32 50 210 22 100 16 53 41 187 120 5468:15-8:30 9 35 50 215 29 104 28 65 45 174 129 5278:30-8:45 8 35 56 202 34 108 21 78 53 189 119 5178:45-9:00 11 40 57 213 39 124 8 73 29 168 88 456

PHF 0.83 0.83 0.77 0.70 0.90 0.92Max 15min 12 69 43 28 61 149Max 60min 40 230 132 78 219 546

SouthboundLeft Lane Through Lane Right LaneTime Period Left Lane Through Lane Right Lane

Northbound

Table 17 - Eastbound & Westbound Peak Hour Factor

6:00-6:156:15-6:306:30-6:456:45-7:007:00-7:157:15-7:307:30-7:457:45-8:008:00-8:158:15-8:308:30-8:458:45-9:00

PHFMax 15minMax 60min

Time Period Right Lane15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min 15 min 60 min

96 581 37 62 505 6579 580 18 27 432 6787 618 32 27 476 53

120 382 552 2331 23 110 14 130 380 1793 65 250103 389 675 2425 31 104 32 100 528 1816 55 24097 407 489 2334 26 112 42 115 440 1824 67 240

120 440 656 2372 23 103 46 134 575 1923 52 23990 410 480 2300 14 94 20 140 398 1941 70 24494 401 613 2238 15 78 22 130 573 1986 60 24977 381 504 2253 19 71 19 107 389 1935 56 23893 354 563 2160 12 60 14 75 521 1881 53 23976 340 594 2274 17 63 29 84 445 1928 51 220

0.92 0.90 0.88 0.76 0.86 0.93120 675 32 46 575 67

440 2425 112 140 1986 250

Right LaneLeft Lane Through LaneWestboundEastbound

Left Lane Through Lane

Table 18 - Northbound Saturation Flow Rate

Time: 3 to 6 pmTotal # of observations = 15

Lane 1 Right-Turn


10 5 10 911 10 11 912 7 12 813 8 13 1014 6 14 1115 6 15 4

Total 27 33 23 35 Total 26 42 28 29

1950.6321 1824.324324

Bound Traffic: North Lane(s): Through; Right Turn




SATURATION FLOW RATE NORTHBOUND

Table 19 - Southbound Saturation Flow Rate


Lane 1 Right-Turn


10 12 10 811 13 11 1112 15 12 913 7 13 814 5 14 615 10 11 15 11

Total 17 34 46 63 Total 25 33 27 42

1594.488 1863.14Saturation Flow Rate Saturation Flow Rate


Obs. No.

Bound Traffic: South Lane(s): Through; Right TurnSATURATION FLOW RATE SOUTHBOUND


Table 20 - Eastbound Saturation Flow Rate


Lane 1 & 2 Lane 3


10 8 10 911 6 11 912 9 12 913 11 13 1514 11 14 1715 13 15 13

Total 13 43 46 47 Total 24 87 0 26

3362.74 1584.352

Average Saturation Flow Rate 1649.031 veh/hr NO SAT FLOW FOR RIGHT TURNING LANE



Bound Traffic: East Lane(s): Through; Right Turn


Obs. No.

SATURATION FLOW RATE EASTBOUND

Table 21 - Westbound Saturation Flow Rate


Lane 1 & 2 Lane 3 Turn Lane

7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh. 7th veh. 8th veh. 9th veh 10th veh.1 6 1 8 1 62 12 2 8 2 63 9 3 6 3 164 5 4 9 4 95 10 5 10 5 106 7 6 5 6 127 11 7 8 7 98 10 8 8 10 8 109 8 9 11 9 6

10 13 10 6 10 911 10 11 11 11 712 9 12 10 12 1113 8 13 6 13 13 714 15 14 6 14 1115 11 15 12 15 10

Total 40 39 42 23 Total 25 46 32 44 Total 25 25 41 48

3058.046 1608.739 1754.196

Average Saturation Flow Rate 1555.595 veh/hr




SATURATION FLOW RATE WESTBOUNDBound Traffic: West Lane(s): Through; Right Turn




Table 22 – Theoretical Saturation Flow Rate

Lane Width

fw

Heavy Vehicles

fHV

Grade fg Parking fpBus Blockage

fbb

Utilization Factor fbb

Area Type fa

Right Turn fRT

Left Turn fLT

Table 9-5 Table 9-6 Table 9-7 Table 9-8 Table 9-9 Table 9-4 Table 9-10 Table 9-11 Table 9-12

L 1900 1 1.00 0.95 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1800T 1900 1 1.00 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1880R 1900 1 1.00 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1878L 1900 1 1.00 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1888T 1900 1 1.00 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1878R 1900 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1893L 1900 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1900T 1900 3 1.00 0.96 1.00 0.95 1.00 0.91 1.00 1.00 1.00 5497R 1900 1 0.97 0.97 1.00 1.00 1.00 1.00 1.00 0.95 1.00 1692L 1900 1 0.97 0.96 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1764T 1900 3 0.97 0.95 1.00 1.00 1.00 0.91 1.00 1.00 1.00 5269R 1900 1 0.97 0.99 1.00 1.00 1.00 1.00 1.00 0.95 1.00 1730

Adjusted Saturation

Flow Rate, S

Theorectical Saturation Flow Rate

Intersection Movement

EB

WB

NB

SB

Adjustment FactorsIdeal Saturation

Flow

No. of Lanes (N)

Table 23 - Calculation of Adjusted Flow Rate

L 40 0.833 48 1 48

T 230 0.833 276 1 276

R 132 0.767 172 1 172

L 78 0.696 112 1 112

T 219 0.898 244 1 244

R 546 0.916 596 1 596

L 440 0.917 480 1 480

T 2425 0.898 2700 0.91 2457

R 112 0.875 128 1 128

L 140 0.761 184 1 184

T 1986 0.863 2300 0.91 2093

R 250 0.933 268 1 268


SB

NB

EB

WB


veh/hrPeak Hour

Factor [PHF]Adjusted

Volume in Lane Group

Lane Utilization

Adjusted Flow Rate [v] in veh/hr

Table 24 – Cycle Length

SouthBound EastBound WestBoundThrough Right Through

198 199 198198 203 199198 200 198

Average 198 201 198Average Cycle

Length

Traffic Light SignalsCycle Length

198

NorthBoundThrough/Right

198198

Through/Right192200197196198

Table 25 - Phase Length

Through Right Through Right Through Right Through Right94 12 99 21 6 4 4 997 12 102 21 4 3 5 992 12 99 21 5 4 5 9

333

Traffic Light Signals

33320

2020 35

3939

Through/Right Through/Right

Amber to RedNorthBound SouthBound EastBound WestBound

Through/Right Through/Right

Green to AmberNorthBound SouthBound EastBound WestBound

Table 26 - Lane Capacity

L 48 N/A N/A 198 N/A N/A N/A N/AT 276 1950.6321 20 198 0.101 197.03 1.401 0.141R 172 1824.3243 20 198 0.101 184.28 0.933 0.094L 112 N/A N/A 198 N/A N/A N/A N/AT 244 1594.4882 36 198 0.182 289.91 0.842 0.153R 596 1863.1397 36 198 0.182 338.75 1.759 0.320L 480 N/A N/A 198 N/A N/A N/A N/AT 2457 1649.0307 93 198 0.470 774.54 3.172 1.490R 128 N/A 12 198 0.061 N/A N/A N/AL 184 N/A N/A 198 N/A N/A N/A N/AT 2093 1555.595 100 198 0.505 785.65 2.664 1.345R 268 1754.196 21 198 0.106 186.05 1.440 0.153

Capacity

WB

NB




Flow Ratio = v/s

SB

MovementAdj. Flow Rate [v] in


Green Time [g] in sec

Cycle [C] in sec

Intersection

EB

Table 27 - Level of Service

k= 0.5 T 0.25 I 1.0 Cycle Length (sec) 198

L 48 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 276 0.101 1.4007767 197.03355 0.33 0.0333 1.0 1.075 1.401 63.536 68.32 FR 172 0.101 0.9333867 184.275184 0.33 0.0333 1.0 1.075 0.93 95.352 102.53 EL 112 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 244 0.182 0.8416494 289.906943 0.33 0.0600 1.0 1.149 0.84 96.240 110.57 ER 596 0.182 1.7593957 338.752679 0.33 0.0600 1.0 1.149 1.76 46.039 52.89 FL 480 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 2457 0.47 3.1721861 774.544721 0.33 0.1550 1.0 1.593 3.17 16.550 26.37 FR 128 0.061 N/A N/A 0.33 0.0200 1.0 1.043 N/A N/A N/A N/AL 184 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 2093 0.51 2.6640224 785.654053 0.33 0.1667 1.0 1.684 2.66 18.393 30.97 FR 268 0.11 1.4404646 186.05109 0.33 0.0350 1.0 1.079 1.44 61.439 66.32 F

Adj. Flow Rate [v] in

veh/hr

Effective Green [g/c]

Lane Group Ratio

C

d in s/vehLOS by

Lane Group Ratio

Level Of Service

WB 34.98 D

NB 85.42 F


LOS by Approach

SB 69.65 E

X [Ratio for Lane

Group]d1 in s/veh

Lane Group Capacity

Rp [Arrival Type 1]

P = Rp x (g/c)fp [Assumed Arrival Type

1]

PF = (1-P)fp/(1-

[g/c])Intersection Movement

EB 26.37

Table 28 - Projected Growth Rate

L 5 0.04 N/A N/A N/A N/A N/AT 5 0.04 1950.6321 2373.24 0.101 197.03 239.72R 5 0.04 1824.3243 2219.57 0.101 184.28 224.20L 5 0.04 N/A N/A N/A N/A N/AT 5 0.04 1594.4882 1939.94 0.182 289.91 352.72R 5 0.04 1863.1397 2266.79 0.182 338.75 412.14L 5 0.04 N/A N/A N/A N/A N/AT 5 0.04 1649.0307 2006.30 0.470 774.54 942.35R 5 0.04 N/A N/A N/A N/A N/AL 5 0.04 N/A N/A N/A N/A N/AT 5 0.04 1555.595 1892.62 0.505 785.65 955.87R 5 0.04 1754.196 2134.25 0.106 186.05 226.36


in veh/hr

Projected Lane Group Capacity [c] 2020 [s] in

veh/hr

Delay by Approach

2015 in s/veh

Intersection Movement# of years

of prediction



veh/hr

34.98

Projected Growth Rate for Year 2020

EB 26.37 32.08 C

WB 42.56 D

NB 85.42 103.93 F

Prejected Delay by

Approach 2020 in s/veh

LOS

SB 69.65 84.74 F

Projected Saturation Flow Rate 2020 [s] in

veh/hr

Assumed Unchanged


SAMPLE CALCULATIONS

Volume Data

The hourly volume is calculated as follows, (V) (veh/hr)

Hourly Volume = ∑ (Vehicles∈15mins intervals for one (1 )hr time period )

Using the East bound through lane as an example

Hourly Volume (veh/hr), 8 am to 9 am = 255+409+307+421

= 1805veh/hr

Peak 15min Value (V15) (veh/hr)

Peak Flow Rate (veh/hr) = Peak Flow Rate (withinhour)

= 490

Peak Hour Factor (PHF)

Again using the East bound through lane as an example

Peak Hour factor (PHF) =Hourly Volume(V 60)

4×Peak Flow Rate (V 15)

Peak Hour factor (PHF), 6 am to 9am =1805

4×490

= 0.92

Saturation Flow Rate (Actual)

Using the calculation for lane 3 (East bound through)

Observed Saturation Flow Rate ,[ SFR ]=3600× ¿of Observations ¿∑ 7 th veh

3+∑ 8 thveh

4+∑ 9 th veh

5+∑ 10 th veh

6

Observed Saturation Flow Rate , [SFR ]= 3600×1573+

934

+375

+366

=1490.8 veh/hr


Given the following information:

Max Hourly Volume (veh/hr), 8 am to 9 am = 1805

Peak Hour Factor [PHF] = 0.92

Lane Utilization Factor [LUF] = 0.0.91

The following calculations are made:

Adjusted Volume (veh/hr) = 18050.92

=1961.95

Adjusted Flow Rate [v] in (veh/hr) = 1961.95×0.91=1785.98

L 457 0.89 513.483146 1.00 513.4831461

T 1805 0.92 1961.95652 0.91 1785.380435

R 51 0.85 60 1.00 60


veh/hr

Peak Hour Factor [PHF]

Adjusted Volume in

veh/hr

Lane Group

Lane Utilization

Factor [LUF]

Adjusted Flow Rate

[v] in veh/hr

EB

Capacity


Adjusted Flow Rate [v] in (veh/hr) = 1785.4

Saturation Flow Rate [SFR] (veh/hr) = 1490.8

Green Time [g] (sec) = 76

Cycle [C] = 191

The following calculations are made:

Effective Green [g/C] = gC

= 76191

=0.398

Lane Group Capacity [c] in (veh/hr) = SFR×gC

=1490.8×0.393=592.94

Lane Group Ratio X ¿vC

=1785.4592.94

=3.011

Flow Ratio = vs=1785.4

1490.8=1.198

L 513.5 N/A N/A 191 N/A N/A N/A N/AT 1785.4 1490.80 76 191 0.398 592.94 3.011 1.198R 60.0 N/A 9 191 0.047 N/A N/A N/A

EB



Lane Group Ratio

Flow Ratio = v/s

Intersection MovementAdj. Flow Rate [v] in


Green Time [g] in

Cycle [C] in sec

Level of Service Calculations


Adjusted Flow Rate [v] (veh/hr) = 1785.4

Effective Green [g/C] = 0.398

Lane Group Ratio [X=v/c] = 3.011

Once X > 1.0, Level of Service = F

Lane Group Capacity [c] (veh/hr) = 592.94

Rp [Arrival Type 1] = 0.33

fp [Assumed Arrival Type 1] = 1.0

We can calculate the following:

P = Rp×( gC )= 0.33×0.398

= 0.131

PF= (1−P ) fp

(1−[ g/C ])

= (1−0.131 ) 1(1−0.398 )

= 1.442

d1= 0.5C(1− g

C )2

(1− gC )X

= 0.5×191 (1−0.398 )2

(1−0.398 )×3.011

= 19.102 s/veh

d= d1PF

= 19.02 (1.442 )

= 27.55 s/veh

= 20> 27.55> 35 s/veh hence LOS by Approach = C

Growth Rate for the Year 2020

Given The following information:

No. of years of prediction (from 2015 to 2020) = 5 years

Traffic Growth Rate = 4%

Saturation Flow Rate [SFR] (veh/hr) 2015 = 1490.8

Assumed unchanged Effective Green [g/C] = 0.398

Lane Group Capacity [c] (veh/hr) 2015 = 592.94

Delay Approach (veh/hr) 2015 = 176.28

We can calculate the following:

Projected SFR 2015 = 1490.8× (1+0.04 )5=1612.45 veh/hr

Projected Lane Group Capacity [c] 2015 = 592.94× (1+0.04 )5=641.32veh/hr

Projected Delay by Approach 2015 = 27.55× (1+0.04 )5=29.80 s/ veh

L 513.5 N/A N/A N/A 0.33 N/A 1.0 N/A N/A N/A N/A N/AT 1785.4 0.398 3.011 592.94 0.33 0.131 1.0 1.442 3.011 19.102 27.55345 FR 60.0 0.047 N/A N/A 0.33 0.016 1.0 1.033 N/A N/A N/A N/A

LOS by Approach

d1 in s/veh

d in s/veh

LOS by Lane

Group Ratio


Lane Group

Capacity [c] in

Rp [Arrival Type 1]

P = Rp x (g/C)

fp [Assumed

Arrival Type 1]

PF Lane Group

Ratio [X=v/c]

Lane Group Ratio

[X=v/c]

Effective Green [g/C]

Adjusted Flow Rate

[v] in veh/hr

MovementIntersection

EB 27.55 C

Resulting in a LOS of F.

https://www.cob.org/documents/planning/growth/fairhaven_high/eis%20info/2009-09-28-trans-Appendix%20A.PDF

https://www.cob.org/documents/planning/growth/fairhaven_high/eis%20info/2009-09-28-trans-Appendix%20A.PDF

http://www.westernite.org/annualmeetings/santabarb12/Compendium/2C-Yu-Sulijoadikusumo

L 2 0.04 N/A N/A N/A N/A N/AT 2 0.04 1490.7972 1612.45 0.398 592.94 641.32R 2 0.04 N/A N/A 0.047 N/A N/A

EB 27.55 29.80 F

Projected Growth Rate for the year 2020

Assumed Unchanged



in veh/hr

Projected Lane Group Capacity [c] 2020 [s] in

veh/hr

Delay by Approach

2015 in s/veh

Projected Delay by Approach

2020 in s/veh

LOSIntersection Movement# of years

of prediction



veh/hr

Projected Saturation Flow Rate 2015 [s] in

veh/hr

Documents

Intro Theory and Calcs