2021-22 Diploma in Traffic Engineering
Traffic Engineering (Part 1)
Assignment
The assignment covers some topics in the module of Traffic Engineering (Part 1).
It is of 100 marks in total. You are required to complete ALL of them.
(Note: The assignment is worth 40% of your total grade / marks in the module.)
Due Date: (by 9:00 pm) 14 February 2022 (Monday)
Question 1 (25 marks)
The Highway Code gives table of the shortest stopping distances for motor vehicle
travelling at various speeds. An extract from the Highway Code is given below.
thinking distance + braking distance = total stopping distance
(a) A driver’s reaction time is 0.7 second.
(i)
Write down FOUR factors which could increase a driver’s reaction time.
(8 marks)
(ii)
What effect does an increase in reaction time have on:
(A) thinking distance (B) braking distance (C) total stopping distance?
(6 marks)
(b) Explain why the braking distance would change on a wet road surface. (3 marks)
1
(c) A motor vehicle was travelling at 30m/s. The driver braked. The graph is a velocitytime graph showing the velocity of the motor vehicle during braking.
The rate at which the velocity decreases (deceleration) is - 30/4.8 m/s2
What is the braking distance? (8 marks)
Suggested Answer:
(a)(i) tiredness / boredom
(a)(ii) A
B
C
drugs / medicine
alcohol / alcoholic drinks
greater / longer
no effect / no change
greater / longer
distraction (8)
(6)
(b)
on a wet road surface: there is less friction (1)
braking distance is greater / takes longer distance to stop or motor vehicle skids / slides
forward (2)
(c)
72 metres (4 marks for steps + 4 marks for answer)
2
Question 2 (25 marks)
(a) Why is a Passenger Car Unit important in assessing highway capacity? (2 marks)
(b) Explain, with an aid of a diagram, why the impact of motorcycles on road capacity is difficult to
measure. (8 marks)
(c) Determine which junction design will you use with the following conditions:
(i) low and unbalance traffic flow for a 3-arm junction;
(3 marks)
(ii) moderate traffic flow for a 4-arm junction, with heavy flow on right-turn movement;
(3 marks)
(iii) moderate and unbalance traffic flow with requirement for better pedestrian crossing facilities;
(3 marks)
(iv) high traffic flow and in order to minimise delay;
(3 marks)
(v) moderate and unbalance/platoon traffic flow and would like to minimize delay for a number
of junctions in an area/district;
(3 marks)
3
Suggested Answer:
(a) PCU is a metric used in transportation engineering, to assess traffic-flow rate on a highway,
essentially the impact that a mode of transport has on traffic variables (such as headway,
speed, density) compared to a single car. (2 marks)
(b) The impact of motorcycles on road capacity is difficult to measure due to their ability to
undertake both lane-based and non-lane-based movements. (4 marks)
(4 marks)
(c) (i)
(ii)
(iii)
(iv)
(v)
Priority Junction;
Roundabout;
Signalised Junction;
Grade-separated Junction;
Signalised Junction;
(3 marks)
(3 marks)
(3 marks)
(3 marks)
(3 marks)
4
Question 3 (25 marks)
(a)
What is the problem of the following combination of the TWO traffic signs? How to
improve it? (5 marks)
(b)
Sketch the stage diagram for the method of signal control after viewing the video. (10
marks)
https://www.dropbox.com/s/kep97phhm2koi3v/20201031_154021.mp4?dl=0
Parking Parking Level Survey
c) What is the purpose of the parking level survey?
(3 marks)
d) During the 24-hour period there is movement between the residential and non-residential
parking demand in respect of time and location. In general, the parking level is steady and
the parking turnover is reasonably constant during the morning, afternoon and night level.
i.
What are these periods last for the morning, afternoon and night level? (3 marks)
ii.
Which level (morning/afternoon/night level) is the most representative of residential
parking demand? and why?
(2 marks)
iii.
If the parking level survey is conducted for the residential development outside the
morning, afternoon and night level stated in b) i), a traffic surveyor claims that a more
reliable results can be obtained. Do you agree and why?
(2 marks)
5
Suggested Answer:
(a) Use “Ahead Only (T.S.106)” instead of the two signs (5 marks)
(b) The stage diagram (10 marks)
Stage 1
Stage 2
Stage 3
Stage 4
(c) The purpose of the parking level survey is to establish the parking demand revealed in an
area.
(3 marks)
(d)
i) Between 0930 and 1230 (morning level);
Between 1430 and 1630 (afternoon level) and
Between 0000 and 0500 the next day (night level)
(3 marks, 1 marks each)
ii) Night level. Because most vehicles in the residential development are parked overnight
and it should generally represent the highest occupation of parking spaces.
(2 marks)
iii) Do not agree. Parking level surveys should generally not be conducted outside the
stated periods as misleading results may be derived due to a fluctuating turnover. (2marks)
6
Question 4 (25 marks)
Parking Demand Estimation and Parking Provisions
A) A Grade-A office building in Wanchai has a total GFA of 24,000 m2.
In Wanchai, average employee space in a Grade A office buildings is typically 15 m2 per
person. The hour between 08:00 to 09:00 is the peak for Wanchai offices, with 90% of
workers having arrived by 09:00 a.m. Since MTR has a station nearby, only 10% of people
who work in Wanchai use private cars for transport to/from work. And according to surveys,
the average car occupancy is 1.2. Given the above information, what is the estimated peak
parking demand of this office building?
(7 marks)
B) The proposed private development at the subject site, which is located inside 500m from
rail station, is for residential usage with 7 residential blocks. With the Domestic Plot ratio of
4.5, the GFA is 65,000m2 for a total of 1,000 households. The details of the development
schedule is shown in the following Table. Referring to the table of Parking Standards for
residential Development (Private Development) from Chapter 8 of HKPSG as attached,
answer the following questions a) to d).
a) What are the minimum and maximum private car spaces for ‘2 Bedroom Type B’?
(6 marks)
b) If the proposed private development is located outside 500m form rail station, what
are the minimum and maximum private car spaces for ‘3 Bedroom Type B’ ?
(6 marks)
c) What are the visitor car parking spaces for the private residential development?
(3 marks)
d) What are the loading/unloading bays for the private residential development?
(3 marks)
Table Details of Development Schedule
Flat Mix Provided
Flat Size Range (m2 )
Total Units provided
2 Bedroom Type A
51-56
100
2 Bedroom Type B
58-65
300
3 Bedroom Type A
80-85
300
3 Bedroom Type B
95.7-98
200
4 Bedroom + 3 toilets
120
100
TOTAL
1,000
7
HKPSG Chapter 8
Section 1 : Parking Standards for Residential Development
8
Question 4
Suggested answer for Part (A)
Total employee nos. = 24,000 m2 x 1 employee / 15 m2 = 1,600 employees
During 08:00 to 09:00 peak period,
Employees arrived to work = 1,600 x 90% = 1,440 employees
Employees arrived to work by private car = 1,440 x 10% = 144 employees
The estimated peak parking demand
= 144 employees / occupancy
= 144 employees / 1.2 employees/private car
= 120 private cars to park
(4 marks for steps, 3 marks for correct answer)
Suggested answer for Part (B)
a) Minimum = GPS x R1 x R2 x R3 = 300 x 1/7 x 1.2 x 0.75 x 1.0 = 38.6 nos.= 39 nos.
Maximum = 300 x 1/4 x 1.2 x 0.75 x 1.0 = 67.5 nos. = 68 nos.
(6 marks: correct equation – 2 marks, minimum and maximum parking spaces –
2marks each)
b) Minimum = GPS x R1 x R2 x R3 = 200 x 1/7 x 2.4 x 1.0 x 1.0 = 68.6 nos. = 69 nos.
Maximum = 200 x 1/4 x 2.4 x 1.00 x 1.0 = 120 nos.
(6 marks: correct equation – 2marks, minimum and maximum parking spaces – 2 marks
each)
c) Visitors car parking provisions = 5 x 7 blocks = 35 nos.
(3 marks)
d) Loading/Unloading bay provisions = 1 x 7 blocks = 7 nos.
(3 marks)
9