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# Project Transportation Engr I have posted the guidelines for the project thanks. CE 3302Traffic StudyDr. Nelson R. Gómez-TorresRajeevRajeevRaj

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Project Transportation Engr I have posted the guidelines for the project thanks. CE 3302

Traffic Study

Dr. Nelson R. Gómez-Torres

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Rajeev

Today’s Learning Objectives

• The student should be able to:

– Safely measure traffic at an intersection

– Produce the project report based on the guidelines set by the professor

– Distinguish between volume (crossing) and demand

– Find the Peak Hour from 5-minute counts

– Calculate Peak Hour Factor from 5-minute counts

– How to measure delays for a movement

– Calculate delays for a movement

2

Purpose of Traffic Studies

• For the student: Understand the process

• Planning

– Identify the need for changes

– See the effect of previous changes

– Calibrate models

• Operations

– Maintain or improve level of service

– Ensure the network is operating as expected

– Verify timings

Variables to measure

• Existing ring diagram and timings

• Volume demand

– Five minutes count considering the queues

– Consider both light (cars, SUVs, etc.) and heavy vehicles (trucks, RVs, etc.)

– Consider direction of travel

• Average vehicle delay

How long to measure?

• In practice, is common to do it over a period of 12 hours

• For this project: Only 2 hours

How to do

• Create a plan and recording method for all the measurements

• Set a time where all counter must be at the site

• Print out everything you need

• Use pencils to write (no pens)

• Have a clock that can be synchronized to the second

– Use phones or tablets as a last option, make sure you set in in airplane
mode

http://www.clker.com/clipart-10366.html

Recommendations

• Dress for the weather and consider changes

• For longer counts water is very important

• To measure queues and delays, good walking shoes

• Good rest the night before

• Do not use your phone

http://www.cap.nsw.edu.au/bb_site_intro/stage1_Modules/WWS-stage1/images/sun.gif

http://www.clker.com/clipart-16506.html

INSTRUCTIONS

http://www.cityofseattle.net/transportation/tfdmaps.htm

Count vehicles and classify them

• You are going to use 5-minute intervals

• You all need to measure the same 5 minutes (the reason will be
clear soon)

• Classify heavy vehicles

https://www.truecar.com/ford/super-duty-f-450/
https://auto.howstuffworks.com/car-driving-safety/safety-
regulatory-devices/car-safety-pictures.htm

Simple Example

chandbook%2F3TrafficCounts.pdf&rct=j&q=manual%20traffic%20counts%20field&ei=2XF_TbP6NdPTgAfG9eGLCA&usg=AFQjCNFAn358W2IX8rp-

Un mejor ejemplo de hoja de conteo

Another Example

Periodo = Period

Comienza = Starts

Termina = Ends

Cola = Queue

VL = Lightweight Vehicle

VP = Heavy Vehivle

Name:________ Date:_______
Site:________ Period:______
3-From Mayagüez 4-From Rincón

Summary Example

http://onlinemanuals.txdot.gov/txdotmanuals/tff/tff-VVS.doc

Measuring queues

• Before the day of the study, see the typical lengths for the queues

• At the end of each 5-minute interval measure the queue

• For long queues, reference points might be needed

When you can’t count the vehicles on queue

http://www.fijitimes.com/images/artpics/57211.jpg

Measuring queues

• The reference points serve the purpose of allowing you to count the
vehicles after the reference point

• You need to estimate the number of vehicles that fit within the
reference points (usually before)

• If the queue is formed by anything other than the traffic signal, you
need to specify it (e.g. vehicle crash)

Example 1

• Let’s say that the approach had the following reference
points

• If you observe 4 vehicles after the 2nd light post, you will
write 2LP+4. Later you will calculate 14+4=18 vehicles

Reference Point Number of vehicles

Stop Line 0

1st Light post 8

2nd Light post 14

3rd Light post 24

Measuring average delay

• One way to measure delays is based on counting vehicles on queue
every 15 seconds for a period of 10 minutes

• In practice, you want to measure the average delay during the worst

• For the project, just select a movement where queues are formed

– You must know this movement before the day of the study

– This uses a different sheet

– The time period MUST coincide with the rest of the traffic count, but only
10 minutes (the start and ends of these 10 minutes must coincide with the
start and end of vehicle counts)

Example 2

• Measuring delay from 7:00AM to 7:10AM

For one movement in one approach

Seconds on each minute

Minute 0 sec. 15 sec. 30 sec. 45 sec.

7:00 AM 2 4 1 3

7:01 AM 3 5 3 0

7:02 AM 6 3 2 1

7:03 AM 4 5 4 3

7:04 AM 2 2 6 4

7:05 AM 4 4 1 1

7:06 AM 5 2 5 5

7:07 AM 1 3 3 3

7:08 AM 4 5 2 2

7:09 AM 2 1 4 2

Subtotals 33 34 31 24
Number of vehicles that crossed during the 10 minutes (not demand) = 100

Example 2 ( cont.)
• Total number of vehicles in queue every 15 seconds (repeated vehicles are ok):

– 33+34+31+24=122 veh

• Assuming that each vehicle was in queue 15 seconds, you can calculate the total delay:
– 122 veh x 15 seconds = 1,830 veh-sec

• The number of vehicles crossing (not demand) the intersection was 100, therefore we can calculate
the average delay per vehicle
– 1830/100= 18.3 sec

REPORT INSTRUCTIONS

http://www.bcps.org/offices/lis/models/fashion/images/checkmk.gif

Calculations

• You measured the volume of vehicles crossing the intersection and
the queue at the end of each period. This is used to calculate
demand.

• The demand can be calculated with the following formula:

VDemand = VCrossing + ∆ queue

Peak hour and Peak hour factor

• In practice: Because we usually measure 12 hours, the data will
show morning peak hour and afternoon peak hour (sometimes
other peak hours can be identified as well).

• For this project: You measured 2 hours, this might not show you a
clear peak hour, but you will select the “hour” that the intersection
had more vehicle demand (this hour might be from 7:35AM to
8:35AM)

file:///C:/Users/Liza Xiomara Rios/Desktop/ejemplo.xlsx

Peak hour and Peak hour factor (cont.)

• After identifying the Peak Hour, you need to identify the highest 15
minutes (to calculate de PHF)

• These 15 minutes for the peak hour 7:35-8:35AM can be from 7:40
to 7:55AM (notice that is not only 7:35-7:50-8:05-8:20-8:35)

• Calculate the Peak Hour Factor (PHF) as shown in class

• Create a histogram of traffic demand

Tabla: Volumen de vehiculos cada 5 minutos por movimiento

14 13 12 21 24 23 Total

6:00 6:05 23 226 15 27 20 50 361

6:05 6:10 20 284 12 19 79 82 496

6:10 6:15 24 213 11 24 92 100 464

6:15 6:20 29 280 22 25 69 90 515

6:20 6:25 14 202 23 28 67 51 385

6:25 6:30 26 279 16 22 56 76 475

6:30 6:35 25 246 19 13 51 76 430

6:35 6:40 14 218 29 27 60 54 402

6:40 6:45 20 443 14 13 95 86 671

6:45 6:50 12 499 29 16 69 79 704 15 min

6:50 6:55 30 383 23 13 88 73 610 Hourly Volume 1985

6:55 7:00 30 500 11 22 55 50 668 6181 1982

7:00 7:05 11 562 12 22 75 53 735 6555 2013

7:05 7:10 13 647 29 22 78 94 883 6942 2286

7:10 7:15 12 586 16 29 99 65 807 7285 2425

7:15 7:20 23 502 23 25 63 65 701 7471 2391

7:20 7:25 30 458 28 26 91 60 693 7779 2201

7:25 7:30 11 312 11 25 77 99 535 7839 1929

7:30 7:35 28 335 26 12 68 59 528 7937 1756

7:35 7:40 25 410 27 10 89 88 649 8184 1712

7:40 7:45 19 320 26 21 91 88 565 8078

7:45 7:50 22 347 12 22 78 82 563 7937

7:50 7:55 16 416 10 30 89 68 629 7956

7:55 8:00 11 311 24 28 70 80 524 7812

8:00 8:05 12 335 14 22 64 74 521 7598

8:05 8:10 13 336 23 27 54 83 536 7251

8:10 8:15 19 326 10 15 94 51 515 6959

8:15 8:20 11 401 25 23 56 67 583 6841

8:20 8:25 17 428 12 22 62 50 591 6739

8:25 8:30 13 413 27 18 50 89 610 6814

8:30 8:35 12 427 23 12 69 79 622 6908

8:35 8:40 16 355 15 14 64 59 523 6782

8:40 8:45 10 228 16 12 51 85 402 6619

8:45 8:50 18 277 29 26 75 84 509 6565

8:50 8:55 21 281 13 12 84 71 482 6418

8:55 9:00 21 229 30 21 91 57 449 6343

Periodo

Movimiento
How to identify the Peak Hour

0

100

200

300

400

500

600

700

800

900

1000

D
e

m
a

n
d

(
V

e
h

ic
le

s)

Period ends (am)

5-minute demand histogram

Peak Hour Factor

http://www.webpages.uidaho.edu/niatt_labmanual/chapters/capacityandlos/theoryandconcepts/PeakHourFactor.htm

Telescope Diagram

28

(a) Morning Peak

(b) Afternoon Peak

Source: Presentation Valdés and Gómez

Report
• The report consist:

– Title page (names of the member of the group, or name of the online
student)

– Introduction (location, times, maps, pictures, description of the things
surrounding the intersection, description of all the other things you are
going to show in the report)

– Traffic Light Operation (show ring diagram, and timings; show all the
approaches; show the view of the traffic light from each approach; show
the position of the controller; show how pedestrians are dealt with; show a
schematic for the intersection).

Report (cont.)
• The report consist (cont.):

– Traffic Study (show the histogram of vehicle demand, with the Peak Hour and the
Highest 15 minutes in the Peak Hour; show percentage of heavy vehicles per
movement and in total; show the telescope diagram; Point towards appendix A
where you will have all the counting sheets; Point towards appendix B where you
will have the table for identifying the peak hour as showed here)

– Average Delay (show the 2 approaches and movements selected with its
calculated average delay per vehicle; point towards appendix C where you will
have the full table for each movement average delay with the corresponding
calculations)

– Conclusion (Briefly describe and show all your findings)

• General: Everything that you show requires a brief explanation of what
you are showing or pointing to.

• Sadly, we are not going to end with a traffic signal design (but we have
courses for that!)

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