Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: THEend8_
TRAN 2080
SECTION B (67%).
3. (a) Define the meaning of traffic flow, density, time mean speed and space mean speed, headway and spacing. [3 marks]
(b) A traffic data collection exercise is conducted by two observers on a
motorway section of 1km in Germany where there is no speed limit.
Observer A is located on the south end of the section while Observer B is located on the north end. Northbound traffic is being observed. Each observer records the time a vehicle passed the point he/she is positioned. Six vehicles have been observed as listed in Table 3.1 and the data recorded by the observers are depicted in Table 3.2.
Table 3.1 List of vehicles observed
|
Number |
Description |
|
(1) |
Orange Audi |
|
(2) |
Purple Honda |
|
(3) |
Blue BMW |
|
(4) |
Red Ford |
|
(5) |
Yellow Mazda |
|
(6) |
Green Toyota |
Table 3.2 Data recorded by observers
|
Observer A at the south end |
Observer B at the north end |
||
|
Time |
Vehicle |
Time |
Vehicle |
|
0 |
(3) |
5 |
(1) |
|
5 |
(4) |
10 |
(2) |
|
15 |
(5) |
15 |
(3) |
|
20 |
(6) |
20 |
(4) |
Two aerial photos of the 1km road section have been taken at the beginning and end of the 25-second observation period. The locations of the vehicles in the two photos are measured and recorded in Table 3.3.
Table 3.3 Positions of vehicles from south end in the aerial photos
|
At t = 0 sec |
At t = 25 secs |
||
|
Position (m) |
Vehicle |
Position (m) |
Vehicle |
|
0 |
(3) |
200 |
(6) |
|
600 |
(2) |
600 |
(5) |
|
800 |
(1) |
|
|
(i) Based on the information from the observers and the aerial
photos, present the trajectories of the traffic in a time-space diagram in Figure 3.1. Indicate clearly the time-space window for the data collected. [5 marks]
Figure 3.1 Time-space Diagram
(ii) Based on your answer to 3(a), and the trajectories of the six
vehicles in the time-space window, verify Equation (1).
q = k × vs (1)
where q is the traffic flow;
k is the traffic density;
vs is the space mean speed. [6 marks]
(iii) Based on your answer to 3(a), and the trajectories of the six vehicles, calculate the observed time-mean speed by Observer A. [2 marks]
(iv) Based on your answer to 3(a), and the observations made by Observer A, calculate the headways and verify Equation (2).
q = h/1 (2)
where
q is the traffic flow;
h is the average headway. [2 marks]
(v) Based on your answer to 3(a), and the aerial photo taken at t = 0 sec, calculate the spacing and verify Equation (3).
k = s/1 (3)
where k is the density;
s is the average spacing. [2 marks]
4. (a) Draw a flowchart showing the structure of the classic four-stage transport model. Clearly show all the stages with the linkages of inputs, outputs and iterations. Explain briefly the inputs and outputs of each stage and what is modelled in each stage. [6 marks]
(b) In a five-zone city, two proposals are being considered: (1) a new suburb
(Zone D) will be developed, which will be connected to the Central Business District (Zone C) with a new highway; (2) a new employment centre (Zone E) will be developed, which will be connected to the Central Business
District (Zone C) with another new highway. The proposal plans are depicted in Figure 4.1.
Figure 4.1 for Question 4(b)
The travel times (in minutes) on the existing road network and potential
future highways are indicated on each link in Figure 4.1. Intra-zonal trips will take only 5 minutes within each zone. The current population size in the five zones is as follows:
Table 4.1 for Question 4(b)
|
Zone |
Population size |
|
A |
3,000 |
|
B |
4,000 |
|
C |
5,000 |
|
D |
1,000 |
|
E |
3,000 |
There are currently 8,000 jobs in the CBD and the new employment centre is expected to provide 2,000 new job opportunities to residents from all
zones. The new suburb (Zone D) is expected to attract 2,000 new residents who will come from suburbs outside the study area.
(i) In the templates provided in Figure 4.2, 4.3 & 4.4, draw out the minimal path trees as specified. [3 marks]
Figure 4.2 Base Case
Current minimal path tree for trips from all origins to CBD (Zone C)
Figure 4.3 With New Highway (1) & (2)
Future minimal path tree for trips from all origins to CBD (Zone C)
Figure 4.4 With New Highway (1) & (2)
Future minimal path tree for trips from all origins to the new employment
centre (Zone E)
(ii) Based on the latest travel survey, the calibrated n-value for a Gravity model for work trips to the town centre was found to be 1.0. Assume that all residents will use the most direct route to travel to work. Estimate the current work trips from A, B, C, D & E to the CBD. [2 marks]
(iii) If the council is to go ahead with both proposals, estimate the
future work trips from A, B, C, D & E to the CBD and the new employment centre (Perform. only Iteration 0). [4 marks]
(iv) If a fixed toll charge of £1 per vehicle is going to be introduced on both proposed highways, based on your calculations above, estimate the total revenue from the commute trips to work. [2 marks]
(v) Based on your calculations above, estimate the total travel time of all residents before and after the improvements. [3 marks]
5. A large suburb North Shore is currently connected to the Auckland CBD by two modes: (1) a motorway that leads to the existing Auckland Harbour Bridge; (2) a busway along the motorway which is for bus use only. Note that although there is also a hilly route through the mountain area, it is assumed that the number of commuters on this route is negligible. With a rapid growth of residents, the government is considering proposals to cope with the growth of demand in a more sustainable manner. As illustrated in Figure 5.1, two transport plans are being considered: (1) a new rail line to be connected to a new second bridge to be used by rail only; (2) a new cycle superhighway to connect the North Shore to an existing ferry service operating between Devonport and Auckland CBD.
Figure 5.1 for Question 5
The current number of work trips from North Shore to Auckland CBD is 8,000 trips per day. The current journey times and travel costs by car and bus are given in Table 5.1.
Table 5.1 Current alternative routes between North Shore and Auckland CBD
|
Route |
Mode-specifc constant Ak |
Journey time (mins) |
Monetary cost/Fare ($) |
|
Car |
2.50 |
30 |
15.00 |
|
Bus |
0.00 |
40 |
5.00 |
From survey results, the Value of Travel Time (VOT) was observed to be
$20/hour for car users and $30/hour for public transport users. A Logit model was calibrated with utility function for different modes as shown in Equation (4):
Uk = Ak −Ck −VOTk × tk
where
Ak is the mode-specific constant for mode k Ck is the out-of-pocket cost (in £) for mode k
VOTk is the Value of Travel Time associated with mode tk is the journey time (in minutes)
(4)
k (in $/minute)
The journey time and cost for the two proposals are given in Table 5.2. The utility function for different modes is the same as in Equation (4).
Table 5.2 Proposed alternative modes between North Shore and Auckland CBD
|
Mode |
Mode-specifc constant Ak |
Journey time (mins) |
Monetary cost/Fare ($) |
|
Rail |
0.00 |
35 |
6.00 |
|
Bicycle + Ferry |
5.00 |
40 + 5 |
8.00 |
The number of work trips of North Shore is expected to increase by 100% to 16,000 in five years.
The authority is considering the following investment options:
Option A (1) To build a new rail line to be connected to a new second bridge to
be used by rail only;
Option B (1) To build a new rail line to be connected to a new second bridge to
be used by rail only;
and
(2) To build a new cycle superhighway to connect the North Shore to an existing ferry service operating between Devonport and Auckland CBD.
Option C To implement both (1) and (2); and
(3) To introduce toll charge on the existing bridge
(a) Calculate the current modal shares of trips from North Shore to Auckland CBD. [2 marks]
(b) Calculate the future modal shares for Option A and Option B. [6 marks]
(c) Calculate the toll charge for Option C in order to reduce the modal share of car to 40%? [4 marks]
(d) Estimate the following income for current situation, Option A, Option B and Option C:
(i) Farebox revenue from bus, rail and ferry services
(ii) Revenue from toll charge
(iii) Total income [4 marks]
(e) Suggest two policy objectives to promote sustainability in transport. Based
on your analysis, what would be your recommended option in this case to support these two objectives? State clearly your reasons. [4 marks]
- 经济Economics
- 金融Finance
- 会计Accounting
- 工商管理Business Management
- 计算机computer science
- 商业分析business analysis
- 法律Law
- 管理Management
- 市场营销Marketing
- 哲学Philosophy
- 心理学Psychology
- 物理Physical
- 统计学statistics
- 电气工程electric engineering
- 化学chemistry
- 生物biology
- 数学mathematics
- 语言学linguistics
- 土木工程civil engineering
- 工程力学engineering mechanics
- 艺术art
PROFESSIONAL HELP!
在线咨询
立即下单
Wechat：THEend8_ 
Email：