2007 INTERSECTIONDATACOLLECTIONANDANALYSIS
Transcript of 2007 INTERSECTIONDATACOLLECTIONANDANALYSIS
2007
INTERSECTION DATA COLLECTION AND ANALYSIS GASVERKSVÄGEN – FISKARTORPSVÄGEN
Sam Kaisiromwe
And
Honghu Zhou
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TABLE OF CONTENTS: Introduction and Background .................................................................2
Objective ..................................................................................................2
Data collection description .....................................................................2
Data Reduction.........................................................................................3
Gap Acceptance .......................................................................................7
CAPCAL Results ........................................................................................9
Round about Results ..............................................................................12
Discussion ..............................................................................................15
Recommendations.................................................................................16
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FISKARTORPSVÄGEN ‐ GASVERKSVÄGEN INTERSECTION
Introduction and Background
Traffic volume studies can help agencies make sound traffic safety–related decisions based on data about critical times of traffic flow, the influence of large vehicles or pedestrians on traffic flow, or trends in traffic volume at particular locations. Traffic volume studies determine the number, movements, and classifications of vehicles (and/or bicycles and pedestrians) at specific roadway locations at specific times. Some examples of traffic volume studies include “rush‐hour” vehicle counts at intersections, pedestrian counts, average daily traffic, and annual average daily traffic.
Fiskartorpsvägen connects Östermalm to Stockholm north, and Stockholm University. Under congestion traffic the priority intersection Fiskartorpsvägen ‐ Gasverksvägen is oversaturated.
Objective The objective of the project is to collect data about the actual situation, analyze them and to suggest design changes to improve safety and performance. Methodology The computer programme CAPCAL was chosen as the tool for analyzing and evaluating the performance of the intersection. Other Geometry data and input speeds and relevant data were collect from the field using data logger and video. The video was analyzed in the lab to get vehicle counts and turning movements.
Data collection description
Automatic data collection methods were used at the junction to collect data. Automatic counting methods are used to gather large amounts of traffic data over an extended period of time. Counts are generally collected for 1‐hour intervals in 24‐hour periods. Automatic counting methods are generally used to determine traffic patterns and trends. The following information can be determined using automatic counts:
• hourly traffic patterns • daily or seasonal variations • growth trends • annual traffic estimates
Observers can use portable or permanent automatic counters in this data collection exercise, portable counters were used. Portable counters consist of automatic recorders connected to pneumatic road tubes. These tubes were connected to an automatic traffic data logger and set to collect data for the specified period. They are typically used to collect the same kind of data collected in manual counts, but for longer periods, usually 24 hours. Permanent counters are
sometimes built into the pavement and used for long‐term counts. The equipment is expensive, and relatively few jurisdictions have access to it. With this method, data on speeds, time, and flow of vehicles can be measured
Video data collection method at the junction was also used, the turning count information, registration number plate identification collected as part of this study was derived from video analysis, where the cameras are mounted so as to capture all the entries and exits to that specified junction over a specified period. These videos were then analyzed manually in the computer lab and the results summarized by time and vehicle types with API programme.
Data Reduction
Fig. 1 shows the position of the junction and turning traffic.
Using the overhead video recordings on DVD, all the points 1, 2…., 6 were viewed and vehicles passing them for every five (5) minutes were counted and recorded as below.
The results show that the through vehicles from K1 to K2 flow least at 48 vehicles per hour and stream 1 (turn right from K1) had the highest flow of 306
vehicles per hour. The rest of the turns registered a flow that was below 200 vehicles
per hour. See table 1 below.
Tab: 1 Number of vehicles passing at each stream point every after 5 minutes point TIME TOTAL FLOW
12:30‐‐12:35
12:35‐‐12:40
12:40‐‐12:45
12:45‐‐12:50 (20 MIN.) V/HR
1 29 32 21 20 102 3062 4 3 6 3 16 483 9 2 2 6 19 574 16 20 13 17 66 1985 16 12 13 23 64 1926 30 17 28 23 98 294
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Fig 2. Relationship between Flow and Speed
Tab: 2 Channel Pair: 2 ‐ 3 Total Report Period: 12:30 to 13:30
K1 K2 K1 K2
Total vehicle identified 705 436 Proportion Proportion
Car 608 368 0.86 0.84
Lorry/Bus 27 21 0.04 0.05 Van/Mpv 19 11 0.03 0.03
Cycle 41 29 0.06 0.07
MC 10 7 0.01 0.02
The table above shows the proportion of vehicles passing at point K1and K2 of the junction. It was observed that 86 percent of the vehicles passing point K1 were passenger cars, 6.0 percent are motorcycles. Vans and lorries/buses were 3 and 4 percent respectively. The rest 1.4 percent were MCs and it was noted that no Semis were observed at that point. At K2 84 percent vehicles registered were passenger cars and the rest shared 16 percent as shown in table 2 above.
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Tab 3: Time taken by identified vehicles to move from K1 to K2
License Plate Colour K1 Time K2 Time K1K2 Time (sec.)
HCU 985 B 12:33:35 12:34:22 47 XUL 743 K 12:37:17 12:38:02 45 OCU 143 Y 12:38:25 12:39:13 48 XGL 082 K 12:38:54 12:39:46 52 JGA 837 B 12:39:40 12:40:32 52 RRK 144 Y 12:41:26 12:42:06 40 WPU 432 B 12:42:19 12:43:02 43 HEJ 131 K 12:43:29 12:44:13 44 LYL 244 W 12:44:10 12:44:56 46 KBN 295 R 12:45:50 12:46:36 46 FCG 861 B 12:46:18 12:47:05 47
XOD 595 X 12:48:30 12:49:21 51
Average = 47seconds.
Table 4: All vehicles number and speed every 5 minutes at K1 and K2 12:30 _13:30
Time K1 Number
AvSpd (kmph)
flow (V/hr.)
K2 Number
AvSpd (kmph)
flow (V/hr.)
12:30 12:35 29 27.19 348 19 22.32 22812:40 31 24.63 372 12 36.02 14412:45 27 27.87 324 14 31.22 16812:50 21 30.42 252 16 27.69 19212:55 32 26.86 384 25 18.54 30013:00 39 26.35 468 16 18.89 19213:05 33 22.7 396 24 26.73 28813:10 22 24.46 264 17 21.16 20413:15 32 27.64 384 13 32.6 15613:20 23 22.44 276 15 26.66 18013:25 35 26.29 420 18 30.79 216
13:25 13:30 28 23.13 336 15 25.17 180Average 25.8 26.5
The all vehicles speeds every after 5 minutes at points K1 and K2 were calculated from API files. The average speed at K1 was found to be 25.8 km/hr and at K2 it was 26.5 km/hr. See table 4 above. The average measured travel time between K1 and K2 was determined in table 3 above as 47 seconds.
The space mean speed between points K1 and K2 was estimated to be the arithmetic mean between the averages of speeds at K1 and K2 i.e (25.8 +26.5)/2. And this gave us 26.2 Km/hr.
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Average delay between K1 and K2 is obtained by getting the time taken to move between the points at space mean speed, then we subtract the actual average measured time of 47 seconds.
• Space Mean Speed = 26.2 km/hr
• Distance between K1 and K2 = 171 m = 0.171km
• Time = Distance/speed = 0.171/26.2 0.006527 hrs. 23.5 seconds. Therefore the delay is given by 47 – 23.5 = 23.5 seconds.
Tab 5: Determination of average delay for the K3 Lane
Point of time Number of Point of time Number of
for observation i Vehicles in queue for observation i
Vehicles in queue
12:30:00 0 12:41:30 5 12:30:30 3 12:42:00 0 12:31:00 2 12:42:30 0 12:31:30 3 12:43:00 0 12:32:00 0 12:43:30 0 12:32:30 0 12:44:00 0
12:33:00 0 12:44:30 2 12:33:30 1 12:45:00 0 12:34:00 4 12:45:30 0 12:34:30 0 12:46:00 8 12:35:00 0 12:46:30 3 12:35:30 0 12:47:00 1 12:36:00 0 12:47:30 6 12:36:30 0 12:48:00 0 12:37:00 0 12:48:30 0 12:37:30 0 12:49:00 5 12:38:00 0 12:49:30 8 12:38:30 0 12:50:00 0 12:39:00 0
12:39:30 4 12:40:00 0 12:40:30 0 Sum N 55 12:41:00 0
Total number of vehicles that were in queue after 20 minutes were 55 Total number of vehicles that had passed the point after 20 minutes were 162
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Using the formula, d = ⅟Q ∑Ni * 30
55x30/162 =10.2 Seconds
Where,
D = average delay
Q = number of departed vehicles in the lane during the studied period
Ni = Number of queuing vehicles at observation i
Note: Delay obtained by the group that used SAVA to determine the difference between the
real travel time and cruise time was about 9seconds.
Gap Acceptance
Introduction Gap acceptance is an essential skill for safe driving. Road crossing is a complex perceptual‐motor task that requires accurate perception of the gap sizes in a dynamic stream of traffic and fine coordination to synchronize the onset of movement with the approaching gap. Understanding how drivers decide that a gap is crossable and how they time their crossing in relation to a moving stream of traffic is critical for the development of training and technology to lower the risk of crashes. Definitions In this study, a gap is defined as the time elapsed between the successive passage of major‐road vehicles as measured from a given reference line. A lag is the time between the departure of a minor‐road vehicle and the arrival of the next major‐road vehicle at a given reference line. The departure time is defined as the time when the vehicle either arrives at or leaves the minor‐road reference line.
Data needed
The collection of quantitative gap data is the first step for any gap acceptance study. The arrivals of vehicles on the major road, and the arrivals and departures of vehicles on the minor road are among the most basic data that need to be collected. In order to capture the arrival of major‐road vehicles, a major‐‐ road reference line is usually used. Many practices exist for recording the arrival and departure of minor‐‐ road vehicles. But in this project, data was collected automatically according at the stop/yield line, using data logger connected to buttons which observers were punching as the vehicle reaches and leaves the stop line. The same vehicle would then be monitored until it reaches point C at K2.
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Results
Headway data comparison is used to check the possible different distributions of available gaps from the reference line on the major road.
Tab 6: Rejected and accepted gaps
Rejected Gap Largest
rejected gap Accepted gap Smallest Accepted gap
1 5 46 6 3 29 5 12 2 28 4 16 2 27 3 32 2 6
Tab 7: Driver Behavior and Conflict Study
Passage Time Section C of Vehicle Identity
Arrival time
Section D
Passage Time Section D
Waiting Time or Follow time
Driver age
Driver genderMinor road D‐
C Pre Major Road B‐C
Next Major Road B‐C
PC 12:46:18 12:46:19 01 Young Female 12:46:20 12:44:05 12:46:30
PC 12:46:26 12:46:34 08 Young Female 12:46:36 12:46:30 12:46:59
PC 12:51:19 12:51:20 01 Old Female 12:51:21 12:50:28 12:51:25
PC 12:51:23 12:51:29 06 Old Female 12:51:32 12:51:25 12:52:06
PC 12:52:25 12:52:26 01 Old Male 12:52:27 12:52:06 12:52:21
PC 12:53:53 12:53:54 01 Old male 12:53:55 12:52:21 12:54:03
HV 12:54:05 12:54:08 03 Old Male 12:54:11 12:54:03 12:54:59
PC 12:54:33 12:54:33 00 Old Male 12:54:35 12:54:03 12:54:59
PC 12:58:38 12:58:38 00 Old Female 12:58:40 12:58:56 12:59:12
PC 12:58:51 12:58:58 07 Old Female 12:59:01 12:58:56 12:59:12
PC 12:59:00 12:59:03 03 Old Male 12:59:04 12:58:56 12:59:12
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CAPCAL Results
The performance of traffic operations at an intersection can be represented by the following measures of effectiveness:
• Degree of saturation (volume/capacity) • Average delay • Average queue length • Distribution of delays • Distribution of queue lengths (i.e. number of vehicles queuing on the minor road) • Number of stopped vehicles
Of recent, environmental costs and operational costs at the junction have emerged to play a big role in any traffic and transport data analysis and evaluation. In addition to operational data, a variety of geometric data have been extracted from the plans. The geometric data are principally various distance measurements, radii, and angles that affect the way in which vehicles traverse the roundabout. Some of the data items can be read directly from the drawings, while others have to be derived from paths or trajectories that are traced through the roundabout based on the manner in which an experienced design engineer thinks the vehicles will travel from entry points to exit points.
Tab 8: Geometry Data. Geometry
Approach Radius RT Angle Gradient (%)
A 24 120 0
B 8 60 0
D 5 90 0
We assumed that the median length for all lanes was 5 m and vehicles were approaching intersection at a speed of 50 km/hr. A 10 % of heavy vehicles correction was also applied. The results were as below.
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Tab 9: Capacity and degree of saturation per lane
Lane Movement Volume (vph)
Capacity (vph)
Degree of saturation
Queue length mean
A 1 RL 460 821 0.56 1
B 1 RT 450 1818 0.25 0
D 1 T 190 1668 0.11 0
2 L 60 722 0.08 0.1
Tab 10: Delay and number of stops per lane
Percent delayed
Approach Lane Delay spv Conflict
Geometric delay.
Total delay Conflict Stops
Geometric delayed Total
A 1 8 5 10 63 23 37 100
B 1 0 4 4 0 0 89 89
D 1 0 0 0 0 0 0 0
2 3 6 6 48 15 52 100
All vehicles 3 4 6 28 10 52 79
Tab 11: Annual Average Daily Traffic AADT
Axle pairs Private cars Heavy vehicles
Heavy vehicles
with trauler Total
A 5668 4669 259 259 5188
B 5855 4823 268 268 5359
D 2927 2412 134 134 2680
Total 14451 11904 661 661 13227
The first output at the junction gave the following results; degree of saturation of lanes A, B, and D were 0.56, 0.25, and 0.11 respectively. Queues were only observed on lane A with the
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queue mean length of 1. The total delay per lane was 10, 4 seconds for approaches A and B respectively. Approach D lane 1 did not register any delay after the CAPCAL runs. The total delay of the junction for all vehicles was recorded as 6 seconds. For more details see tables 9 and 10 above
It should be noted that, as vehicles are delayed, stopped at any junction, they tend to use more fuel and experience tyre worn outs, thus a capital cost to the owners. However as they consume more fuel, they emit dangerous gases such as corbondioxide, nitrogen oxide and others. These gases are a problem to the environment and therefore to people around the junction. A value is always attached to such externalities in order to measure the extent of their destruction. The table below shows the valued problems that are associated with the junction.
Tab 12: Total Costs per year of the intersection.
Private cars
Heavy vehicles
Heavy vehicles with trailer Total
Fuel costs 107454 12116 61427 180997
Vehicle costs
Capital 48110 36907 104536 189553
Tyre 4854 6720 10189 21764
Total vehicle cost 52964 43627 114726 211317
Environmental costs
NOX 7561 10715 64396 82672
SO2 12 2 10 24
VOC 5331 ‐215 350 5466
Particles 0 0 0 0
CO2 153119 24555 124488 302162
Total 166024 35057 189244 390324
Time costs
Value of time 780607 78717 78717 938040
Value of goods 0 3644 18221 21866
Total 780607 82361 96938 959906
Total 1107048 173161 462335 1742544
Accident costs 710737
Total incl. accident costs 2453281
Round about Results
Roundabouts represent a unique blending of operations, safety, and design, where changes to one element appear to have a significant effect on the others. A roundabout intersection brings together conflicting traffic streams, allows the streams to safely merge and transverse the roundabout, and exit to their
desired direction. Drivers approaching a roundabout must slow to a speed that will allow them to safely interact with other users, and to negotiate the roundabout. As drivers approach the yield line, they must check for conflicting vehicles already on the circulating roadway, and determine when it is safe to enter the one‐way circulating stream.
Some definitions
Three performance measures are typically used to estimate the operational performance of a roundabout: degree of saturation, delay and queue length. Each measure provides a unique
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perspective on the quality of service at which a roundabout will perform under a given set of traffic and geometric conditions
Tab 13: Capacity and degree of saturation per lane
Lane Movement Volume (vph)
Capacity (vph)
Degree of saturation
Queue length mean
A 1 RL 460 1421 0.32 0
B 1 RT 450 1426 0.32 0
D 1 T 190 1098 0.17 0
2 L 60 1046 0.06 0
Tab 14: Delay and number of stops per lane
Percent delayed
Approach Lane Delay spv Conflict
Geometric delay.
Total delay Conflict Stops
Geometric delayed Total
A 1 0 5 3 15 0 85 100
B 1 0 4 3 14 0 86 100
D 1 1 7 4 38 1 62 100
2 1 9 3 35 0 65 100
All vehicles 0 5 3 20 0 80
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Tab 15: Total Costs per year for the round about.
Private cars
Heavy vehicles
Heavy vehicles with trailer Total
Fuel costs 84410 10286 55093 149790
Vehicle costs
Capital 44396 31331 90057 165784
Tyre 2825 3912 5931 12668
Total vehicle cost 47221 35243 95988 178452
Environmental costs
NOX 7148 9371 58054 74573
SO2 9 2 9 20
VOC 4759 ‐440 332 4652
Particles 0 0 0 0
CO2 120283 20846 111652 252781
Total 132200 29779 170046 332026
Time costs
Value of time 454365 45818 45818 546001
Value of goods 0 2121 10606 12727
Total 454365 47939 56424 558728
Total 718196 123248 377552 1218996
Accident costs 382850
Total incl. accident costs 1601846
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Discussion
Summary of the results for the junction and roundabout
In this summary we shall look at the main indicators of performance in both scenarios, these are Delay, Queue length, Degree of saturation and externalities costs.
Tab 16: Comparison between the Intersection and Roundabout.
Intersection Roundabout %change
1 Queue length A 1 0 B 0 0 D 0 0
2 Total Delay 6 5 17 A 10 3 70 B 4 3 25 D 6 4 33 3 Degree of saturation A 0.56 0.32 B 0.25 0.32 D 0.11 0.17 4 Total Costs Vehicle & fuel costs 392,314 328,242 16.3 Environmental costs 390,324 332,026 14.9 Time costs 959,906 558,728 41.8
Accident costs 710,737 382,85 46.1 TOTAL 2,453,281 1,601,846 34.7
The queue length was identified on the arm A (K3) of the junction with a length of 1, this was reduced to zero after the roundabout implementation. Total delay for the whole junction reduced from 6 minutes to 5 minutes after the implementation of the roundabout. This was a 17 percent reduction in delay. The arm A delay was mostly reduced from 10 seconds to 3 seconds, a 70 percent reduction. Arm D of the intersection had a total delay of 6 seconds that were later reduced to 4 seconds after the roundabout implementation this reflected a 33 percent reduction.
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Degree of saturation is defined as the ratio of flow to the capacity of the road. It is known that the less the value of degree of saturation the better the road in study. On average the degree of saturation reduced from 0.30 at the intersection to 0.27 for the roundabout, showing that the capacity of the intersection increased with a change to roundabout.
The total costs at the roundabout reduced from 2,453,281 at the intersection to 1,601,846 for the roundabout, a reduction of 34.7 percent. Accident costs per year reduced by 46.1 percent after implementing the roundabout.
Recommendations
We recommend that the intersection be redesigned into a round about because the queue will disappear and the delay at the junction will reduce. Also the maintenance costs to vehicle owners will reduce and we noted that the environmental effects will improve.
Limitations:
Because of the nature of data collection from the field, the input data into the API files may not be accurate due to the following reasons
• The difference between observing and pressing of buttons (response time and pressing error) for different data collectors
• Topography of the area which especially from the K3 arm that did not give drivers a good clearing distance to the intersection.
• Only vehicle traffic is analyzed, pedestrians and cyclists are ignored
• The study period is too short to make any sound conclusions.
References
• Transport Planning and Traffic Engineering By C A O’Flaherty
• Improvement of Traffic Performance and safety of four intersections on Kringlumy’rarbraut in Reykjavik(Master’s Thesis) By SGRUN MARTEINSDOTTIR