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2 the blackspot investigation process
1. How engineers investigate
blackspots
Semarang
23rd & 24th April 2012
Phillip Jordan, Consultant
Road Safety International Pty Ltd
2. How to investigate a blackspot
Aims of this presentation:
to outline the blackspot investigation process
to encourage you to look for low cost, high benefit
countermeasures
to show you some recent Indonesian blackspot investigations
to outline some of the lessons learnt
3. On Indonesian highways and roads:
• Many crashes – mainly motorcycles, pedestrians
• Road safety is a growing community concern.
• Crash data – getting better and more accurate.
• Few “champions” of road safety engineering – yet!
• There is much to do to improve road safety.
• We (engineers) should start by treating blackspots.
• But limited experience with blackspot treatments.
4. What is a Blackspot ?
A blackspot is a location on a road which has a high
number of crashes – fatal, serious or minor. It may
be an intersection or it may be a length of road.
In Victoria (Australia) – it is 3 casualty crashes in 5 years.
In 1980 when the Victorian blackspot program started – it
was 12 casualty crashes in 3 years.
There has been great success over 30 years.
5. What is a Blackspot ?
For Indonesia we give:
• 10 points for each fatal crash
• 5 points for each serious casualty crash
• 1 point for all other crashes
• Any site with more than 15 points = blackspot
• Any 1km length with more than 30 points/km = black length
• This is the starting point as we sift through candidate sites.
18. To treat a blackspot: 1
1 Establish a list of blackspots
– Search Police crash data for high crash frequency sites.
– Seek one kilometre lengths with high numbers of crashes.
– Talk with the Police, use local knowledge. Identify those
intersections and lengths within each kilometre where it is
known there have been many crashes.
– Gather all the Police reports for the site – read them.
19. Police can assist with blackspot identification
Road safety engineering issues for
Indonesia
20. Police can assist with blackspot identification
Road safety engineering issues for
Indonesia
21. Police can assist with blackspot identification
Road safety engineering issues for
Indonesia
22. To treat a blackspot: 2
2 Obtain and read all Police crash report forms.
– Gain a “picture” of the crash history of the site.
– Work with Police – ask them for details of the crashes that may
not be in the reports.
23. To treat a blackspot: 2a
2aDraw a collision diagram.
– Easy to do – but messy, so do a rough draft first
– For each vehicle – draw an arrow to show its direction
– Show m/c, pedestrians, cars, trucks, buses differently
– Make sure that the point of impact is accurately shown
27. To treat a blackspot: 2b
2b Draw a crash factor grid (Matrix)
– Easy to do – use Microsoft Excel if you have it.
– Paper will also do.
– For each crash – summarise all the known details in one
column.
– Add rows if extra information is known from the Police reports.
32. To treat a blackspot: 3
3 Diagnose the problem
Look at the Collision Diagram and the Crash Factor
Matrix – are there any patterns?
Day time vs night time?
Wet vs dry?
Type of crash - head on, or run-off-road etc
Type of road user?
Direction of travel?
33. To treat a blackspot: 4
4 Inspect the site – at the time that the patterns of
crashes have happened!
If night time – inspect at night!!
Put yourself in the shoes of the people who had the
crashes.
Ask - Why did they have their crash?
34. To treat a blackspot: 4
4 Be logical ......
Only use countermeasures that will reduce the crashes
(For example, if crashes happened mainly during daytime,
do not install street lighting as a countermeasure).
$$ are always limited – so look first for low cost options.
(Don’t use a bomb to kill a mouse).
35. •Inspect site – day and night.
•Assess likely causes.
•You are like a doctor at this
stage – diagnosing your patient
to prescribe the best medicine!
36. • If a patient visits a doctor, the doctor asks about his illness.
• The doctor does not just guess about his illness – he does not want to
treat the patient for a headache when he has a heart problem.
• You are like a doctor at this stage – diagnosing your blackspot!
• The blackspot cannot speak – you have to look, listen and ask locals.
• This takes time, skill, patience and logic
37. 6 7 8 9 10 11 12 13 14
18.6 18.7 18.7 18.7 18.7 18.7 18.7 18.7 18.8
11/04/2 10/03/2 27/02/2 25/06/2 19/08/2 12/12/2 10/07/2
011 012 10/07/2011 11/07/2011 011 011 011 011 011
06:15:0 15:00:0 16:30:0 07:30:0 10:30:0
0 21:45:00 02:00:00 13:30:00 0 0 0 13:00:00 0
1 0 1 1 0 1 0 0 1
0 0 0 0 0 0 0 0 0
0 1 0 0 1 0 3 2 1
Fine Fine Fine Fine cloudy Fine Fine Fine Fine
Good Good Good Good Good Good Good Good Good
Medium Medium Unkno
m/c m/c m/c m/c m/c m/c
Truck Truck wn
Mini
m/c m/c m/c m/c
Bus
9 5 74 81 63 2 64 94 21
1 0 1 1 1 1 1 1 1
7 1 2 2 2 8 3 2 2
1 1 1 1 1 1 1 1 1
Review the Collision Diagram
Review the Crash Factor Grid
Use these on-site to help decide what countermeasures
are needed
39. Police can assist with blackspot information
Police can assist with blackspot information
40. Tips for the site inspection
• Visual deceit
– Not all drivers/riders see the road the same way.
– You need to try to look at the road as others “might”
41. The driver’s view is straight ahead - but the road goes left!!
Visual deceit
USA - RHS
42. The driver’s view is straight ahead - but the road goes left!!
CRASH
Visual deceit LHS
43. Pantura – East Java.
How/ why has this barrier been damaged?
Why would anyone run off the road here?
45. To treat a blackspot: 5
5 Develop countermeasures – talk with colleagues,
with DGLT, with Police
Keep simple, keep low cost
Persevere – there will be many locations where
suitable countermeasures will be possible.
46. Your list of low cost countermeasures
Signs – warning, regulatory, direction
Line marking
Delineation
Shoulder sealing
Roadside hazard removal
Geometric changes
Speed limits
Traffic signals
Roundabouts
Lighting
47. To treat a blackspot: 6
6 Design, and then cost the work
- Finalise the design
- Work out the cost of the proposal
48. To treat a blackspot: 7&8
7 Write your blackspot report
8 Send for approval for funding; put this site into the Works
Program
Ensure to implement the agreed countermeasures(s).
It is no use for the road users unless we
make positive changes to the location.
50. Into the future – maybe 3 or 4 years – there
will be competition for funding within the
blackspot program. Then you will have to
rank sites so that funds are spent on those
sites that will return the “best value” to the
people of Indonesia
51. How will we determine cost and benefits?
1 We need to know the benefits to be gained $
2 We need to know the cost of the countermeasures $
3 Then we calculate the benefit/ cost ratio
52. How will we determine cost and benefits?
1 We need to know the benefits to be gained $
How many crashes do we expect to save,
and how much does each one cost?
53. How will we determine cost and benefits?
2. We need to know the cost of the countermeasures $
This is something engineers are good at
calculating.
54. How will we determine cost and benefits?
1 After you have established countermeasures
2 Get the Crash Reduction Factor (% from list)
3 Have a crash cost ($)
4 Work out the value of the benefits of the countermeasures ($)
5 Calculate the cost of the works ($)
6 Calculate the benefit/ cost ratio
55. Example of calculating the benefit cost ratio
To work out the BCR we need to know the benefits
(in $) of the countermeasures, and the cost (in $) of
the countermeasures.
56. Benefits - Indonesia needs to have a
table that shows the Crash Reduction
Factor for each countermeasure
What percentage of crashes at the blackspot
will be reduced if we seal the shoulders of
the highway for one kilometre?
59. If there were (say) 16 crashes at the location in 3 years –
and 12 of these are motorcycle crashes - you would aim to
prevent 50% of these 12 crashes in the next 3 years – that
is 6 crashes in the next 3 years
If each crash costs IDR100,000,000 – you will claim
benefits of IDR600,000,000 over 3 years – or
IDR 4,000,000,000 for the life of 20 years
Benefits = IDR4,000,000,000
Crash reduction factors based on real experience from the
Victorian (Australia) blackspot program since 1980
60. If the cost to seal the shoulders is (say) IDR200,000,000
The Benefit/Cost Ratio will be 4,000,000,000 / 200,000,000
BCR = 20.0
This project will be compared with all other blackspots in
your Balai – those with the highest BCR’s will be treated
first. The others will wait for next year.....
61. 20:1 BCR is excellent
But for now – concentrate on developing the
most suitable countermeasures
BCR’s will only be needed for new blackspots
after a few more years time
62. Some Indonesian blackspots
• Two blackspots at bridges – one rural, one
urban
• One blackspot at a Y junction
• A blackspot at a small cross road intersection
in a small town
• A blacklength on a Highway in Sumatra
• A black spot on a curve on a By-Pass
71. Blackspot
Location
AERIAL PHOTOGRAPH OF BLACKSPOT LOCATION IN MENTENG, CENTRAL JAKARTA
72.
73. The visibility before going over the crest of the bridge is obstructed, and the driver has no
information about the presence of loop in front. The driver may know the road has four
lanes , but the first and second lane are forced to turn left.
74. This direction sign was too late for the road user who
wants to turn left to Sumenep/Latuharhary.
74
75. The loop has very small radius. It is dangerous if a driver misjudges it and has a higher
speed than should be. The driver need to be warned with a speed limit of 30 km/hr.
RECOMMENDATION
76. The island is not quite visible at a distance. There is a problem of
delineation. It needs more guide posts.
RECOMMENDATION
77. MONAS MONAS
MANGGARAI SUDIRMAN HARMONI HARMONI
SALEMBA
KOTA KOTA
RECOMMENDATION
78. MONAS
HARMONI
KOTA
MANGGAR
AI
SALEMBA
RECOMMENDATION
94. Blackspot inspection – near the Mosque, Jambi By-Pass
Blackspot inspection – near the Mosque, Jambi By-Pass
95. Blackspot inspection – near the Mosque, Jambi By-Pass
Blackspot inspection – near the Mosque, Jambi By-Pass
96. RECOMMENDATIONS
• Repair pot holes
• Seal shoulders
• Install edge lines, centre line
• Install speed restriction signs
• Cut back vegetation to increase sight lines
98. 7 crashes in 12 months at U turn
Pantura (National Highway) Km 18.7
99. What will you recommend to
reduce the crashes at this U turn
on this busy, fast National
Highway?
100. Blackspot investigations
• The investigation team
should put itself in the
shoes of the road users...to
identify why some of them
are have crashes at the site.
