{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

CEE3610--PrelimExam12010-Solution

# CEE3610--PrelimExam12010-Solution - CEE 3610 Introduction...

This preview shows pages 1–3. Sign up to view the full content.

CEE 3610 – Introduction to Transportation Engineering Spring, 2010 Prof. M.A. Turnquist Prelim Exam 1 -- Solution 1. (12 points) During the first week of the course, I talked about how the six “criteria air pollutants” regulated by the Federal Clean Air Act have declined (in the aggregate) by more than 50% since 1980. However, one of those six pollutants remains the single dominant source of exposure in non-attainment areas within the U.S. a) What is that single pollutant? Ground level ozone (just ozone is sufficient) b) Why is the transportation system of particular importance in making further reductions of that pollutant in the future? Ozone is formed in the atmosphere through a reaction that involves oxides of nitrogen (NOx), volatile organic compounds (VOCs) -- which are mostly unburned hydrocarbons from fuel -- sunlight and heat. Motor vehicles are a major source of both NOx and VOCs. 2. (10 points) Suppose the relationship between speed and density for a highway facility is - = j f k k u u 1 where: u f = free-flow speed k j = jam density. Further suppose that u f = 70 mph and k j = 144 veh/lane/mile. What is the absolute capacity of a single lane on this facility? Volume is expressed as the product of speed and density: 5 . 1 833 . 5 70 144 1 70 k k k k ku q - = - = = To find the density at which volume is maximized, we set 0 = dk dq : 64 8 ) 833 . 5 ( 5 . 1 70 0 ) 5 . 1 ( 833 . 5 70 5 . 0 = = = = - = k k k dk dq veh/lane/mile.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
At k= 64, 33 . 23 3 70 12 8 1 70 144 64 1 70 = = - = - = u mph. Therefore, 1493 ) 33 . 23 ( 64 = = q veh/hour. 3. (11 points) In developing the equation for the speed of a wave front ( u w ) separating two different regimes of traffic density (see figure below), a key part of the argument is writing the equation: 1 1 2 2 ( ) ( ) w w u u k u u k - = - . Why is this equation valid? 1 2 k 1 k 2 u 1 u 2 u w w This equation says that the flow of vehicles (q = uk) leaving area 1 in the diagram and crossing the wave front must be equal to the flow of vehicles entering area 2 across the same wave front.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}