Investigating Pedestrian Injury Crashes on Modern Roundabouts in Addis Ababa, Ethiopia Getu Segni...
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Investigating Pedestrian Injury Crashes on Modern Roundabouts in Addis Ababa, Ethiopia Getu Segni Tulu, Md. Mazharul Haque, Simon Washington, Mark King 1
Investigating Pedestrian Injury Crashes on Modern Roundabouts in Addis Ababa, Ethiopia Getu Segni Tulu, Md. Mazharul Haque, Simon Washington, Mark King
Investigating Pedestrian Injury Crashes on Modern Roundabouts
in Addis Ababa, Ethiopia Getu Segni Tulu, Md. Mazharul Haque, Simon
Washington, Mark King 1
Slide 3
Outline Background Methods Result Discussion and Conclusions
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Slide 4
Background 3 -Roundabout introduced 40 years before (1) -Modern
roundabouts have four main features
Slide 5
Background (cntd) Roundabouts reduce the number of crashes and
injury severity level Safety performance of roundabouts in
developing countries not known Many differences in roadway,
traffic, and road users behavior 65% of vehicles are more than 15
years old 40% of total fatal crashes in Africa pedestrians (2) 85%
of total injury crashes are pedestrians (3,4) 4
Slide 6
Background (cntd) Objective of the Research to develop crash
prediction models of pedestrian crashes at roundabouts using
geometric, traffic and land use characteristics affecting
pedestrian safety to propose potential remedial measures 5
Slide 7
Methods Data collection Four categories of data collected from
22 modern roundabouts three years pedestrian crashes exposure
variables: ADT, Pedestrian crossing volume roadway and traffic
variables number of lanes, roundabout configuration (four-legged or
three-legged), posted speed limit, maximum gradient of the
approach, presence of a concrete barrier as a divider, 6
Slide 8
Methods (cntd) presence of a bus stop within 50m of the yield
line on an approach road presence of raised medians, presence of a
footpath, presence of a fence along the footpath spatial Variables/
site characteristics school zone within 100m of the roundabout,
availability of alcohol-serving bars within a 300m radius of the
roundabout, land use (roundabout was located in office and
commercial areas), and the presence of a public transport terminal
beside the roundabout 7
Slide 9
Methods (cntd) develop the pedestrian safety performance
function using count model Random effect models (6,7) Random effect
Poisson Model (REP) Random effect Negative Binomial model(RENP)
Model Evaluation and Selection Criteria (8,9) 8
Slide 10
Result: Random Effect Poisson Model 9 VariablesCoff.IRRStd. Err
ZP>|z|[95% Conf. Interval] Constant -9.71***
3.23-3.010.00[-16.04, -3.39] Log of the product of major road and
minor road AADT (aadt1 aadt2) 0.82**2.260.392.100.04[0.06, 1.58]
Log of average daily pedestrian crossing volume
0.65**1.920.322.050.04[0.03, 1.28] Maximum gradient of major
approach road 0.11***1.120.042.950.00[0.04, 0.19] Presence of
raised medians on approach road -0.41**0.660.18-2.290.02[-0.77,
-0.06] Availability of terminals beside the roundabout
0.50***1.650.202.530.01[0.11, 0.89] Presence of schools at 100
meter radius -0.38*0.680.20-1.870.06[-0.78,-0.02] Note:***,**,*
significance at 1%, 5%, 10% level respectively
Slide 11
Discussion & Conclusion REP model is marginally superior
RENB model in explaining pedestrian crashes two exposure variables
the product of major road and minor road AADT and pedestrian
crossing volume design proper pedestrian crossing infrastructure
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Slide 12
Discussion & Conclusion (cntd) Provision of raised median
along major roads Gradient of approach road and stopping sight
distance should be properly designed Special intensity pedestrian
exposure when roundabout near to public transport terminals Entry
and exist of pedestrians and vehicles far from roundabout influence
areas reduce the vehicle-vehicle and pedestrians conflicts Equips
sidewalks with pedestrian fence to reduce illegal crossing 11
Slide 13
Discussion & Conclusion (cntd) 12 Typical modern
roundabouts in Addis Ababa Suggested improvement on existing modern
roundabouts
Slide 14
References 1.Solomon, T.G., Capacity evaluation of roundabout
junctions in Addis Ababa, in Civil Engineering Department. 2007,
Addis Ababa University Addis Ababa: Addis Ababa 2.WHO. (2013b).
Pedestrian safety: a road safety manual for decision-makers and
practitioner 3. Downing, A., G. Jacobs, A. Aeron-Thomas, and J.
Sharples, Review of Road Safety in Urban Areas. 2000, Transport
Research Laboratory and Department for International Development:
London. 4.Jacobs, G., A. Aeron-Thomas, and A. Astrop, Estimating
global road fatalities. 2000, Transport Research Laboratory and
Department for International Development: London. 6. Washington,
S.P., M.G. Karlaftis, and F.L. Mannering, Statistical and
Econometric Methods for Transportation Data Analysis. 2011, New
York: Taylor & Francis Group. 7.Lord, D. and F. Mannering, The
statistical analysis of crash-frequency data: A review and
assessment of methodological alternatives. Transportation Research
Part A: Policy and Practice, 2010. 44(5): p. 291-305. 8. Akaike, H.
Information Theory and an Extension of the Maximum Likelihood
Principle. in Second International Symposium on Information Theory.
1972. Budapest Akadmiai Kiad. 9. Schwarz, G., Estimating the
dimension of a model. The Annals of Statistics, 1978. 6: p.
461-464. 13
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14 Thank you Ethiopian Roads Authority (Ato Zaid W/gebrial, Ato
Bekele Nigussie, Ato Alemayehu Ayele) Ato Tatek Abera Rama
Consulting Engineers Ato Efrem G/ Egziabher Lidet consultants Ato
Andualem Haile Georgis STADIA Consultant