Vehicle Delay Study

1. Vehicle Delay Study

2. Before anything else • Read the manual carefully. It is your homework • What is covered in the following slides is just general

3. General • Determines LOS of lane group/approach • Measured by seconds delayed for eachvehicle! • Simplification of Highway Capacity Manual HCM

4. 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

5. Collect the data • For illustrations let us study delay of an exclusive left turn lane

6. 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.

7. 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

9. Numbers in that column can’t be true!

10. Data Analysis • Two calculations are needed • General calculations • For sake of LOS determination

11. Data Analysis • General calculations

12. Data Analysis • General calculations

13. 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:

14. Data Analysis

15. LOS • Compare that number to the following table

16. Calculations • repeat this analysis for the other approaches of the intersection • Prepare a graphical representation for the delay and LOS of each lane group

17. Interpret and conclude • Answer questions in manual • Prepare your presentation