Homework 1 (HW 1) / Due: Mon. 8 September 2008
CE361 HW 1- 1 -
RED LIGHT RUNNING
In this HW, you may work with as many as three partners. Each member of your group must sign the front page of the HW that you submit. Use 1.5- or double-spacing.Answer the questions below in a clear, concise fashion. Hint: It would be helpful to observe a signalized intersection and discuss your ideas with someone else.
- (15 points) A definition for the average citizen. Aclear, concise definition of red light running that The City Engineer can use when being interviewed or when talking to citizens. Give him a sentence (or two or three) tomemorize.
Source:
A driver is running a red light if his/her vehicle enters the intersection when the signal controlling the driver’s movement is red. By “entering the intersection”, I mean the vehicle has crossed the stop bar.
- (15 points) A definition for the traffic engineer. Define red light running to another traffic engineer.
Add to the citizen’s definition as follows. Approach and entry speeds must be legal. The yellow phase must be long enough to give the driver adequate time and distance in which to stop before the stop bar.
- (20 points) Data to collect. In FTE Sections 2.1 and 2.2, traffic parameters and methods for measuring them are presented. Which data are needed to determine whether a particular vehicle has run a red light? Assume detectors are present that can record the following: vehicle location at time signal begins red phase, vehicle approachspeed and speed at stop bar. Approach speed = speed at distance from stop bar = speed limit * length of yellow phase. Check to see if that distance also permits a safe stop once yellow phase starts. If it doesnot, use safe stopping distance to determine approach speed. How would these data be used to make that determination? Even if the detectors are not at the stop bar, detectors upstream and downstream from the stop bar can be used to compute vehicle speed and determine the time crossing the stop bar by interpolation. Likewise, multiple detectors on the approach can be used to compute approach speed.
- (35 points) Systems specification. Using the general criteria for system specifications given in FTE Section 1.3.2 and the definitions and data needs you have cited above, create a systems specification that could be used to help detect red light running at all signalized intersections in downtown Mythaca. Simply follow the 7-item structure in FTE Section 1.3.2. The list format on FTE pages 25-26 is preferable to FTE Tables 1.4 and 1.5, because the list format will allow you to better explain and justify your specifications, as needed. As you develop your system specification, please keep in mind a common complaint about red light running enforcement, i.e., that catching drivers running red lights is more about generating revenue through fines than about improving safety. Make sure your specs are designed to improve traffic safety.
- What is the purpose of this system? To detect vehicles that run red lights at downtown Mythaca signalized intersections and create a report that tabulates the number of violations on each approach at each intersection.
- What is the area of coverage for this system’s specification? Signalized intersections in downtown Mythaca
- What are the technical specifics of the system’s intended mission/use? Be able to provide the data described in Problem 3 of this Homework for at least [95] percent of the vehicles approaching downtown Mythaca signalized intersections.
- What is the capacity of the system? Be able to detect and analyze data [for vehicles arriving at a rate of 1800 vehicles per hour per lane].
- What is the availability or operational readiness when the system is called into use? The system should be available and operational [at all times] during the life of the project.
- What is the reliability of the system in operation? The occurrence of false positives or false negatives must be less than [five] percent.
- What is the cost-effectiveness of the system? If this detection system indicates that red light running is not a major problem, the costs of an enforcement system can be avoided. If this detection system is converted into an enforcement system, the benefits of the collisions avoided can be compared against the cost of the system. Each collision avoided will have a benefit, depending on whether the collisions avoided are fatal, personal injury, or property damage only, based on historical crash data.
Your work will be evaluated according to how useful the City Engineer would find your definitions and specifications.