Download - Vehicle Delay Study

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Page 1: Vehicle Delay Study

Vehicle Delay Study

Page 2: Vehicle Delay Study

Before anything else Read the manual carefully. It is

your homework What is covered in the following

slides is just general

Page 3: Vehicle Delay Study

General Determines LOS of lane

group/approach Measured by seconds delayed for

eachvehicle! Simplification of Highway Capacity

Manual HCM

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Collect the data Choose intersection

Signalized intersections Choose time of day

Usually peak hour Choose the approach

You may need to zoom in further to a specific lane group

Exclusive left turn is studied by itself

Page 5: Vehicle Delay Study

Collect the data For illustrations let us study delay

of an exclusive left turn lane

Page 6: Vehicle Delay Study

Collect the data First observer counts and records

the number of vehicles stopped on the left lane for each 15 seconds interval

A vehicle is counted more than once in the delay determination if it is stopped during more than one sampling time.

Page 7: Vehicle Delay Study

Collect the data The second observer performs a

separate tabulation of the lane volume for one minute intervals by classifying the vehicles as either stopped or not stopping.

At least 350 cars must be counted

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Numbers in that column can’t be true!

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Data Analysis Two calculations are needed

General calculations For sake of LOS determination

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Data Analysis General

calculations

ondssec9.9233

2310233

15541eper vehicl delayed seconds

delayed vehiclesof volumeTotal15intervalsdelay in vehiclesofNumber eper vehicl delayed seconds

Page 12: Vehicle Delay Study

Data Analysis General

calculations

%57409233delayed volume totalof %

100counted vehiclesof volumeTotal

delayed vehiclesof volumeTotaldelayed volume totalof %

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Data Analysis For sake of LOS determination

Correction factors: acceleration deceleration Vehicles processed in less that 15 sec

All of that is accounted and used in the simplified way:

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Data Analysis For sake of LOS determination

ondssec3.73.140923103.1

40915541eper vehicl delayed seconds

3.1counted vehiclesof volumeTotal

15intervalsdelay in vehiclesofNumber eper vehicl delayed seconds

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LOS Compare that number to the

following table

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Calculations repeat this analysis for the other

approaches of the intersection Prepare a graphical representation

for the delay and LOS of each lane group

Page 17: Vehicle Delay Study

Interpret and conclude Answer questions in manual Prepare your presentation


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