CE 361 Introduction to Transportation Engineering
Posted: Wed 13 October 2010
Homework 6 (HW 6) Solutions
Due: Fri. 22 October 2010
EVALUATION OF PROJECTS FOR SAFETY AND EFFICIENCY
Dear Consultant:
The County wishes to determine your ability to evaluate projects as it
begins to undertake a concerted effort to improve the safety and
efficiency of local transportation systems. Part of your qualification
process to bid on county traffic safety projects involves your ability
to provide clear and correct solutions to problems related to recent
and upcoming projects. In this assignment, as in all previous
assignments, you are expected to:
*
Work alone or as part of a group of up to three CE361 students.
Group members must sign the front page of the work submitted.
*
Label each problem with its name.
Failure to comply with these requirements will result in penalties.
1.
Project evaluation. A private health care provider builds an
Automated People Mover (pictured at right) to connect its two
hospitals that are one mile apart. Before the APM was built,
doctors, nurses, staff, visitors, and even patients went from one
hospital to another by going to their parked cars, driving to the
other hospital’s parking garage, then walking to their
destinations. This would take about 30 minutes. The same trip by
APM would take ten minutes. 1000 passengers ride the APM on an
average day, including weekends. The APM cost $40 million to build
and costs $1.12 million per year to operate.
A.
(5 points) If the value of travel time is $25/hour, what is the
dollar value of travel time saved each year?
B.
(15 points) How many years (to the nearest 0.1 year) will it take
for the benefits of the APM to justify the costs? Use a discount
rate of 2.9 percent per year. Explain your procedures.

A.
A3 Annual time savings 365 days/yr * 1000 pax/day * (1/3 hr
saved per pax) * $25/hr VoT $3.042*106.
P1
4.00E+07
cost to build
B.
Set up a worksheet like the one at left. A2 annual cost to
operate.
Find P2 PW of A2 after n in [P|A] factor can be determined. In the
worksheet, “sum P” P3 – (P1 + P2) because P3 is the PW of annual
benefits of time saved, P1 is cost to build and P2 is PW of annual
costs to
A2
1.12E+06
ann cost to operate
A3
3.04E+06
ann time savings
i
0.029
discount rate
n
32.372209
years
P|A
20.8152645
factor
P2
2.33E+07
PW ann op costs
P3
6.33E+07
PW ann time savings
sum P
9.69E07
operate. Calc [P|A] factor using eqn in FTE Fig 5.4: [P|A,i,n]
with n to be determined. The value of n affects the
values of [P|A], P2, and P3. Find n such that sum P 0 by trial and
error or by Solver feature of worksheet. The value of n is 33.4years.
2.
Crash data. To demonstrate your understanding of Processes 1 and 2
in FTE Figure 6.4, click on Tippecanoe County’s “2008 Vehicle
Crash Report”. In Table 60, find the intersection of SR 26 E/South
St and 3rd St. (It is in downtown Lafayette, one block south of
the courthouse.) Also read the footnotes below Table 60. Traffic
count maps are available at
http://www.tippecanoe.in.gov/egov/docs/1179334154747.htm. Show
your calculations and compare the results of your calculations
with the entries in Table 60.
A.
(10 points) South Street is oneway EB; 3rd Street is oneway SB.
What are the approach ADT values for the NB, SB, EB, and WB
approaches? What value of MEV should be used in the MEVrate
equation in the Crash report? How does it compare with the MEV
value in Table 60?
The excerpt of the traffic count map that includes the intersection of
South Street and 3rd Street is shown below. The SB approach ADT is
5482 (2007 count); the EB approach ADT is 12,750 (2008 count).

Equation 1 on page 25 of the Crash Report is . V1 is the north
(SB) approach. V1 5482. V4 is the west (EB) approach, V4 12,750.
MEV 365*(V1+V2+V3+V4) 365*(5482+0+0+12,750) 365*18,232
6,654,680 6.655*106. In Table 60, MEV 6.655. The values match.
B.
(20 points) For the 3year period 20062008, what is the value of
A (crash frequency) for use in Equation 1 for the intersection of
South and 3rd Streets? Use Equation 1 to calculate the MEV Rate
for this intersection.
A 18.67 crashes per year.
MEVrate 2.805. Equals Table 60 entry.
C.
(10 points) Use Equation 2 to calculate the CRF for this
intersection. What value of Ra did you use and how did you
determine it?
Equation 2 on page 25 is . Ra 1.6066 from the “***” footnote
under Table 60 for Urban Principal Arterials.
CRF 1.6066 + 0.808 + 0.075 2.490 vs. 2.098 in Table 60
for the intersection of South and 3rd Streets. Values do not match.
3.
FTE Exercise 6.19 Racing the Train.
a.
(5 points) Car’s x1 800 – (0.6 sec * 1.47 fps/mph * 55 mph)
800 – (0.6 * 80.85) 800 – 48.51 751.49 ft from tracks
b.
(15 points) Find time for car to reach 85 mph.
v1 v0 + at; t 1.575 sec.
Find distance for car to reach 85 mph.
x 127.34 + 34.73 162.07 ft, which is less than the
distance to the tracks. The car will be traveling at 85 mph for the
rest of the distance to the tracks, which is: 800 – 48.51 – 162.07
589.42 ft.
Mode
t sec
V fps
ft traveled
dist to Xing
reaction
0.6
80.85
48.51
751.49
Car
accelerate
1.575
up to 124.95
162.07
589.42
constant V
4.72
124.95
589.42
0
6.895
Train
constant V
6.895
58.80
405.43
594.57
c.
(10 points) Time car will travel at 85 mph to tracks
4.72 sec. Time for car to reach tracks 0.6 + 1.575 + 4.72
6.895 sec. At this time, where will train be? 1000 ft – (1.47 * 40
* 6.895) 1000 – 405.43 594.57 feet from the crossing.