LAB1 Spot Speed Study

CE EN 562 - Traffic Engineering; Characteristics and Operations LAB #1: SPOT SPEED STUDY AND ANALYSIS

Required reading: Robertson, Hummer, and Nelson, Manual of Traffic Engineering Studies, 4th Ed., Institute of Transportation Engineers, 1994 & 2000. (Available in the Reference Drawer in the CEEn Department Office) Chapter 3 - Spot Speed Studies (or Chapter 9 of the text) Conduct a spot speed study using a radar gun. You may form data acquisition teams consisting of two persons each. Each team is to make an independent study, collecting speed data of at least 100 vehicles randomly selected, or for a one hour period, whichever comes first. The data should be collected during daylight hours and preferably during the afternoon off-peak period. Choose a mid-block location on 900E. When measuring approach speeds for a signalized intersection, be sure to collect them at a mid-link location upstream of the intersection where the effects of the red light (that is, queued up vehicles) would be minimal. Be certain to select an observation point which assures the most objectivity for your study. Also be certain to do nothing that would constitute a hazard to yourselves or the public. Each student will submit an individual report. following information: 1. 2. 3. 4. 5. 6. 7. 8.

Each report should contain the

Mean, mode, and range Histogram Cumulative frequency distribution 15th and 85th percentile speeds 10 mph pace Chi-square goodness-of-fit test to determine if the data is normally distributed. A determination of the necessary sample size if the error between the sample mean and the true mean is to be less than 1 mph with a level of confidence of 99.0% Check if 100 samples are good enough, if the tolerance (or precision) is ±2.0 mph.

The submitted report should have the following format (Following the format is important): 1. 2. 3. 4. 5.

Title page Table of contents Introduction Summary of results (attached sheet) Graphs: histogram and cumulative frequency distribution

6. 7.

Discussion of results, conclusions, and recommendations Appendix: raw data and Chi-square calculations

This report is to be completed and turned in by: within a week from the assigned date unless otherwise noted in the course schedule web page.

SPOT SPEED STUDY SUMMARY SHEET General Information: Study performed by: _______________________________________________________________ Location: _____________________________________________________________________ Direction of Traffic Studied: ________________________________________________________ Posted Speed:

_________________ mph

Day, Date, and Time: __________________________________________________________ Description of Study Site (conditions, set-up, light, control of bias, etc.):___________________ Study Results: Sample Size:_________________ vehicles Mean Speed:_________________ mph 85th Percentile Speed: Mode:

_________________ mph

_________________ mph

15th Percentile Speed: Speed Range:

_________________ mph

_________________ mph

10 mph Pace:

_________________ mph

Standard Deviation:

________________

% of total exceeding posted speed:

_____________ %

% of total traveling >5 mph over posted speed:

_____________ %

% of total within the 10 mph pace:

_____________ %

Chi-square tabulated value (critical Chi-square value):

_____________

Chi-square calculated value:

_____________

Chi-square test conclusion:

______________________________________

Sample size required for less than a 2 mph difference between the true mean and the calculated mean with a 95.0% level of confidence:_____________

vehicles