INTERSECTION SAFETY and LANE DEPARTURE RESEARCH

1
INTERSECTION SAFETY and
LANE DEPARTURE
RESEARCH

• KAREN SCHURR, PE
• Lecturer/Researcher
• UNL Civil Engineering Department/
  Nebraska
  Transportation Center

April 8th, 2009 - Kearney, NE
2
The CHALLENGE
3
The CHALLENGE
2007 41,059 people killed in road traffic
crashes
Grand Island, NE Pop 42,940
4
The CHALLENGE
2007 Motor vehicle crashes are the leading
cause of death for citizens 4 to 34 years of
age.
Source Texas Transportation Researcher, April
2009, page 3
5
The CHALLENGE
2007 2,500,000 road traffic crash injuries
South Dakota Pop 755,000
Nebraska Pop 1,774,000
6
The GOOD NEWS
4 DECLINE IN FATALITIES FROM 2006! HISTORIC LOW
OF 1.37 FATALITIES PER 100 MVM
1.28 FATALITIES PER 100 MVM
IN FIRST 10 MONTHS OF 2008!
Source www.usatoday.com 4/6/2009
7
American Association of State and Highway Transpo
rtation Officials
1.0 DEATHS PER 100 MVM
2005 Strategic Highway Safety Plan
8
The LATEST GOOD NEWS
2007 256 fatalities in Nebraska
2008 207 fatalities in Nebraska
-19!!!
9
Why?

• High gas prices, bad economy fewer miles driven
• Better laws
• Record high seat belt usage

10
ROAD SAFETY IMPROVEMENTS THROUGH
RESEARCH

• Science-based foundation
  based on
  high-caliber research
  studies
• Identify and prioritize best research
  opportunities
• Ensure reliable and useful results
• Avoid unnecessary duplication

11
DRIVER
VEHICLE
ROADWAY
12
MULTI-DISCIPLINARY EFFORT

• Civil Engineering
• Mechanical Engineering
• Statistics
• Psychology
• Public Health

13

• Limited in quantity
• Varied in quality

CRASH DATA RECORDS
14
INTERSECTION SAFETY and
LANE
DEPARTURE RESEARCH
ROUNDABOUTS Whats the latest and greatest?
15
ROUNDABOUTS and SAFETY

• GOOD NEWS over the last 40 years!
• We are past the first day with new hands
  phase
• Roundabouts have improved overall crash
  rates, particularly injury type in urban,
  suburban and rural settings over
• 2-way and control.

Resource NCHRP 572, 2007
16
ROUNDABOUTS and OPERATIONS

• Still getting used to it
• Drivers are still tentative ?efficiency reduced
• Driver behavior is largest variable affecting
  roundabout performance
• Few US sites have reached capacity and those
  are at capacity for only short time periods

Resource NCHRP 572, 2007
17
ROUNDABOUTS and PED/BICYCLE
SAFETY

• Very few problems but
• Exit lanes place
  peds/bikes
  at more risk than
  entries
• Drivers less likely
• to YIELD

18
ROUNDABOUTS and PED/BICYCLE
SAFETY

• Very few problems but
• 2-Lane legs harder
  to cross due to non-YIELD
• driver behavior

19
Operational and Safety Effects
of Central Island Landscaping
at
Single-Lane Roundabouts
20
How does sight
blockage across central
island effect driver
behavior?
21
BLOCKED VIEW
CLEAR VIEW
22
Two Schools of Thought

• BLOCK view across central island
• - Attractive landscaping area
• - Blocks view of opposing vehicles

Lincoln, NE
23
Two Schools of Thought

• CLEAR view across central island
• - Full view enhances driver orientation
• - Better view of peds and bicyclists

Lincoln, NE
24
Forgiving Roadside
25
URBAN, RESIDENTIAL
Before
After
BLVD
MINOR ST
26
Opportunity knocks
3 months of time between
end of construction and
central island landscaping
27
View from Camera
NORTH
28
THE STUDY BEFORE AFTER Evaluate
changes No Trees
vs Trees Measures of Effectiveness - Free flow
vehicle speeds 10 ft, 150 ft in
advance of ped Xing and in circulatory
roadway - Critical Gap - Follow-up Time
X
29
12 Speed Data Sites
150 ft from Xing
10 ft from Xing
Splitters
30
Immature Spruce Tree Sight
Blockage
31
Mature Spruce Tree Sight
Blockage
32
Before Trees
Data collected 3 months after
opening
After Trees
Data collected 9 -12 months after
opening
33
9 of 12 study sites had significantly LOWER
speeds in the AFTER case

150 ft, 1.0 mph
Statistically similar


10 ft, 1.3 mph
Splitters, 0.4 mph

34
10 of 12 study sites had significantly SMALLER
standard deviations in
the AFTER case

150 ft, 0.8 mph
Statistically similar
10 ft, 0.4 mph
Splitters, 0.3 mph


35
1.0 mph lower
1.6 mph lower
0.7 mph lower
36
40 mph
30 mph
20 mph
Speed, mph
37
BEFORE-AFTER STUDY RESULTS Speed
Analysis
Grouped Speeds
Locations Circulatory roadway 150 ft away from
Xing 10 ft away from Xing
Significance No Yes Yes
Independent sample t-test (a.05) for
comparison of means
38
CONCLUSIONS Speed Analysis

• Speeds at 10 and 150 ft from ped Xing were
  significantly lower in the after period.
• Speeds were more uniform in the after period.
• Upper percentile speeds lowered.
• ? Safety increases for drivers,
• pedestrians and bicyclists
  at the roundabout.

39
CONCLUSIONS Capacity Analysis

• Lower limit of tc in AFTER period decreased
  compared to
  tc in
  BEFORE period
• ? Approach capacity potential increases.

40
Recommended DOs
Central Island
Landscaping
DO plant landscaping in central island. DO use
elongated plant material. DO space high plants
strategically to
maximize view between
elements. DO be mindful of the impacts of
full-grown size of plant material. DO be mindful
of the drifting effect large plantings may cause
and plan arrangements to minimize snow build-up
in the circulatory roadway.
41
Recommended DOs
Central Island Landscaping
DO be mindful of deciduous foliage that may drop
within circulatory roadway and make it slippery
if wet. DO plant vegetation that has year-round
foliage (evergreens) to maximize
visibility of central island for drivers. DO
plant woody vegetation that will have a full
grown stump of around 4
inches in diameter or less. DO use plantings that
will require minimum maintenance. DO provide
training to local residents for proper safety if
neighborhood groups volunteer to maintain
landscaping.
42
Recommended DONTs
Central Island
Landscaping
DONT place a fountain in the central island

if the local area tends to be windy.
43
Recommended DONTs
Central Island
Landscaping
DONT grade steep slopes in central island so
errant vehicles can negotiate it without severe
injury (flatter than 16).
44
Investigation and Mitigation
of Driver Confusion
at Modern Roundabouts
45
Driver Surveys Distributed
Cities with roundabouts Norfolk Blair
Omaha Lincoln
Cities without roundabouts Plattsmouth
46
Driver Surveys Distributed
47
Survey Findings

• Unfamiliar, non-confident drivers have greater
  potential for incorrect negotiation than
  familiar, confident ones.
• Older drivers have greater potential for
  incorrect negotiation than younger drivers.
• PC drivers have a greater potential for
  incorrect negotiation than SV drivers.

48
Survey Findings
1
Responses
1
2
3
49
Survey Findings
Responses
1
2
3
50
Current
Nebraska Drivers Manual Contents
51
Successful Variable Message Signs
52
http//www.dmv.ne.gov/examining/pdf/engdrivermanua
l.pdf
FACT OVER 60 OF FIRST-TIME APPLICANTS FAIL
THE WRITTEN DRIVERS TEST.
53
INTERSECTION SAFETY and

LANE DEPARTURE RESEARCH
Source Driving Down Lane-Departure Crashes A
National Priority, AASHTO,
April 2008
54
Causes of Run-Off-Road Crashes
Percent Total Annual ROR
Crashes
Source Driving Down Lane-Departure Crashes A
National Priority, AASHTO,
April 2008
55
Speed-related crashes seem
to be more closely linked with
curvature Drivers unintentionally depart their
lane
Source Volumes 4-20, NCHRP Report 500
56
Strategies to reduce head-on
crashes 1. Install centerline
rumble strips for
2-lane roads
Strategies to reduce Run-Off-Road
collisions 1. Install shoulder
rumble strips
Source Volumes 4 and 6, NCHRP Report 500
57
THE FUTURE ITS safety application of
lane-departure warning system
showing camera
tracking lane markings
Source Nissan
58
THE FACTS We know how to reduce roadway
departure crashes Data-driven decisions and
cost-effective implementations are taking place
in the US Research is being undertaken
to further
determine the relationship
between safety-operational-design
elements Practitioners are providing
training Political guidance is being provided
by challenging goals for safety
improvements
59
MOVING Toward
a CULTURE of SAFETY
Source Texas Transportation Researcher, April
2009, page 3
60
Safety Culture Involves 3 Groups Policymakers
, Current Future Drivers
Source Texas Transportation Researcher, April
2009, page 3
61

• POLICYMAKERS
• BE MORE AWARE OF CRASHES
• BECOME STRONG PROPONENTS OF SAFE
  DRIVING BEHAVIOR

62
CURRENT DRIVERS BE CONVINCED THAT
CHANGING DRIVER BEHAVIORS
WILL PRODUCE
LONG-TERM PERSONAL AND SOCIETAL
BENEFITS
63
FUTURE DRIVERS BE INSTILLED WITH THE
SOCIAL CONSCIENCE NECESSARY TO NOT ONLY
FIT IN, BUT TO HELP KEEP THE SYSTEM
SELF-SUSTAINING.
64
POLITICAL WILL
SOCIETAL WILL

INFORMATION
65
RESEARCH NEEDS

• Well-conceived national agenda
• Researchers working with safety program managers
• Formulate projects
• Shape proposals
• Conduct research
• Monitor ongoing research
• Review results
• Varied in quality

66

• What can U
  do today
• on a professional level?
• on a political level?
• on a personal level?