High Crash Location – Lancaster at Sunnyview Final report

Department of Civil and Environmental Engineering
CE450/550 Transportation Safety Analysis
High Crash Location – Lancaster at Sunnyview
Final report
By Jasna Kolasinac, Zhubin Najafi, David Ruelas, Qianwen Lu
June 6, 2011
1
TABLE OF CONTENTS
Introduction
………………………………………………………….. 3
Site Description
………………………………………………………….. 4
Methodology
………………………………………………………….. 5
Data analysis
………………………………………………………….. 6
Countermeasures
………………………………………………………….. 8
Recommendations
………………………………………………………….. 13
References
………………………………………………………….. 14
Appendix
………………………………………………………….. 14
DISCLAIMER
“This report is the result of an academic exercise. The results and recommendations are the
opinions of the student authors only and is not intended for distribution or use outside of
Portland State University.”
2
INTRODUCTION
A safety analysis of a high crash location at the intersection of Lancaster Drive and
Sunnyview Road in the City of Salem was conducted. The site is located just east of
Interstate 5 Freeway. The intersection experiences the second most number of crashes in the
City of Salem. The intersection with the highest number of crashes is directly north of this
intersection at Lancaster Drive and Market.
For this project, the group evaluated the intersection at Lancaster Drive at Sunnyview Road
for safety improvement recommendations. The group is of the belief that if crashes occur at
a high rate at this site, that engineering treatments may be established through the evaluation
to help each user of the transportation facility. An aerial map denoting the study site can be
seen in figure 1 below.
Figure 1: Lancaster Drive at Sunnyview Road
3
SITE DESCRIPTION
Lancaster Drive at Sunnyview Road is in a commercial area of the City of Salem. Lancaster
Road is considered to have Medium High Annual Average Daily Traffic (AADT) between
20,000 to 40,000 vehicles and Sunnyview Drive is considered to have Medium traffic volume
at 10,000 to 20,000 vehicles per day.
Below you will find a condition diagram showing all the traffic signals and signage found at
the intersection as well as its geometry.
Figure 2: Condition Diagram
4
METHODOLOGY
Techniques typically used in safety evaluations were used at these intersections. However,
none were found to be statistically significant, meaning there wasn’t anything greatly unusual
at this intersection that would imply a safety treatment was needed. Instead, the team relied
heavily on observations at the site and interviewing people around the intersection.
Field observation
The four team members visited the site on Tuesday, May 10th afternoon during the start of
the afternoon peak period. The site visit allowed the group to gather primary data on the site
and experience firsthand the operations of the location and driver behavior as well as
pedestrian and bicycle activity. Some immediate observations were;
•
Visual Clutter – too many large signs by area businesses at heights similar to traffic
signs. Some sight obstructions such as poor landscaping were also exhibited.
•
Access Management – access points to businesses are too close to the intersection.
•
Driver Behavior – Drivers seemed aggressive, particularly in getting into left-turn
lanes and into private driveways and business entrances.
Figure 3: Visual Clutter
5
DATA ANALYSIS
A look at the crashes at the intersection uncovered that 32 crashes occurred and were coded
to the intersection for the three year period of 2006, 2007 and 2008. Collision diagrams for
analysis purposes of the three years as well as 2009 were created and can be found in the
appendix
Data were collected using the Oregon Transportation Safety Data Archive (ORTSDA). A
Chi-Square Test and a Proportions Test was calculated for the intersection using the data.
Most found crash type at study intersections were:
•
•
•
Left-turn collision
Rear-end collision
Angle collision
As mentioned in the methodology section above and seen in table 1 below, statistical data
does not show any major differences.
Chi-Square Test
Study area (2008)
Obsereved
Crashes
expected
Crashes
X
Left
Rear end
Angle
2
9
2
1
9
3
Sum
0.377
0.001
0.138
0.516
2
0.516 < 5.9915 → fail to reject Ho : conclude that the crash pattern is the
same as statewide experience
Table1: Chi-Square Test for Intersection
The following data for statewide crashes were used and prepared the proportions:
6
Statewide sites:
Crashes
Percent
Left
Rear end
Angle
Wet
Dry
Total crashes
100
700
200
300
700
1000
10
70
20
30
70
Table 2: Statewide Data Used for Proportions Testing
Proportions testing were also used in analyzing the data. As shown in table 3 below, this
method also proved to be insignificant in showing any unusual trends in the crash data.
Proportions Test
Z-Left
0.641
Z-Rear-end
-0.060
Z-Angel
-0.414
Z-wet
-0.542
Z-dry
-0.661
all Z*<1.96 → fail to reject Ho : conclude that the crash pattern is the
same as statewide experience
Table 3: Proportions Test Results
7
COUNTERMEASURES
Countermeasure #1: Bus Lay-By
Countermeasure #1 is to improve flow at the current bus stop on Lancaster Dr. at the
northwest corner of the intersection by providing a bus bay (or lay-by). At this stop, umber
11 bus comes every 15 minutes during weekdays and blocks the right lane, causing a queue
behind it as shown in figure 4. There is an underutilized parking lot behind the stop. The
proposed design would acquire part of the parking lot to construct a turning bay for the bus
(see figure 5 and 6). This would reduce the queue during peak hours, eliminate vehicles
making erratic movements in order to avoid the queue, and more importantly, it would
reduce the number of crashes at this intersection especially for rear-end and side-swipe
crashes. However, a concern about this countermeasure is that bus drivers can experience
difficulties when pulling out of the lay-by to rejoin the traffic flow. This can cause delays to
the bus service and may lead to bunching of buses.
Figure 4: Bus Causing Queue
8
Figure 5: Potential Bus Bay Design
Figure 6: Example Bus Bay
9
Countermeasure #2: Increase Left-turn Green Phase
The protected left turn signal time on Lancaster Dr. was observed to be too short. It does
not get all the demand through during peak hours. Cars were seen speeding up and then
abruptly stopping, potentially causing rear-end crashes as seen on the collision diagrams. The
countermeasure proposes to increase the left-turn-green time on Lancaster Dr. by reducing
the green phase length on Sunnyview Rd. without changing the signal cycle length for the
intersection. This is an inexpensive alternative, but it can cause delay on Sunnyview Rd.
Figure 7: Traffic Signals at Intersection
Countermeasure #3: Improve Signs and Signal Appearance
Currently there exists visual clutter at this intersection. Visual clutter can cause drivers to get
distracted or become confused as to movements at the intersection. Through this
countermeasure all signs should be placed at the same height and have uniform lettering.
City of Salem transportation staff should work with the Planning Department to enforce
commercial sign codes and rewrite signage codes to eliminate unnecessary or distracting
commercial signs around the intersection. The protected right turn signal should be
eliminated as it adds to the clutter and can be deemed contradictory since a red ball and
green arrow appear at the same time.
10
Countermeasure #4: Remove bike lanes
Bike lanes on Lancaster are rarely used due to high motor vehicle traffic volume and poor
riding conditions (figure 8). This alternative removes bike lanes and increase lane widths and
turning radius to allow for safe turning of trucks on Lancaster. However, the cost of this
alternative may include road marking and adding bus lanes on other roads.
Figure 8: Misuse of Bike Lane
11
Countermeasure #5: lane configuration signs
Due to the high traffic volumes and on Lancaster Dr., there is an increasing chance for
vehicles to miss proper chance to safely change lanes and then tend to weave to the left-turn
lane near the intersection during congestion period. The narrow lanes on Lancaster make
this movement more dangerous which causes rear end and side swipe crashes. The
countermeasure is to add signs upstream of weaving section showing lane configuration to
prompt drivers to change lanes early enough to avoid sudden moves (See figure 9). Based on
budget constraints, this alternative is more cost effective compared to increasing the lane
width.
Figure 9: Signage Notifying Drivers
12
CONCLUSION/RECOMMENDATION
It is recommended that the countermeasures outlined in this report be further analyzed by
the City of Salem for implementation and budgetary purposes. No single countermeasure
stands out as being most effective at this point. Implementation of a mix or of all the
countermeasures is likely most advantageous. Along with the countermeasures, an aggressive
outreach and educational campaign targeted at motorists in the project area is also
recommended. In speaking with some businesses surrounding the intersection, aggressive
driver behavior seems to be exhibited regularly.
Pedestrians must also be considered high priority in order to increase safety at the
intersection. Despite conditions not typically conducive of a pedestrian environment, many
pedestrians were found utilizing the facilities. There is opportunity to make livability
improvements at this location for all users, especially to pedestrians that will add to the
vibrancy of the area.
13
References
1. City of Salem (2010). “University of Oregon Sustainable Cities Initiative.” <
http://www.cityofsalem.net/scisalem> (Apr, 2011).
2. Turner, S., Fitzpatrick, M., Brewer, M., and Park, E., “Motorist Yielding to
Pedestrians at Unsignalized Intersections: Findings from a National Study on
Improving Pedestrian Safety,” Transportation Research Record: Journal of the
Transportation Research Board, vol. 1982, no. 1, pp. 1-12, Jan. 2006.
3. City of Salem (2007). Salem Transportation System Plan: Providing Mobility for a
New Century, City of Salem Public Works Department Transportation Services
Division, Salem, OR.
4. Federal Highway Administration (2009). Manual on Uniform Traffic Control
Devices for Streets and Highways, 2009 Edition, U.S. Department of
Transportation, Federal Highway Administration, Washington, DC.
5. E. Hauer, “Fishing for safety information in murky waters,” Journal of
transportation engineering, vol. 131, p. 340, 2005.
6. C. M. Monsere, P. G. Bosa, R. L. Bertini, and others, “Combining Climate, Crash,
and Highway Data for Improved Ranking of Speed and Winter-Weather Related
Crash Locations in Oregon,” Journal of Transportation Engineering, vol. 134, p.
287, 2008.
7. E. Hauer, Observational before-after studies in road safety: estimating the effect
of highway and traffic engineering measures on road safety. Pergamon, 1997.
8. A Policy on Geometric Design of Highways and Streets (2001). American
Association of State Highway and Transportation Officials, Washington D.C.
Appendix
Collision Diagrams
14
SAT MAR 10
DRY 2006
5PM
DAY
N
Collision
Diagram
2006
3PM SUN MAY 27
DAY
WET 2006
1 PM FRI JUL 20
12 PM TUE SEP 11
DAY DRY 2006
DAY UNK 2006
UNK SUN AUG 12
DAY
DRY 2006
10PM WED MAY 16
DLIT
DRY 2006
10AM FRI MAR 16
DAY
WET 2006
WET 2006
DAY
SAT MAR 3
10AM
SAT JAN 6
UNK 2006
DLIT
11AM
SAT MAR 9
8PM
DRY 2006
WET 2006
DLIT
DAY
FRI OCT 5
8PM
SUNNYVIEW
L
A
N
C
A
S
T
E
R
15
DRY 2007
WED JUL 24
DRY 2007
6PM
DAY
THR AUG 29
1PM
DRY 2007
DAY
DLIT
DAY
DRY 2007
SUN MAY 12
DAY
8PM
FRI MAY 3
SUNNYVIEW
3PM
MON NOV 11
DRY 2007
DAY
DRY 2007
DAY
1PM
TUE MAY 14
DRY 2007
DLIT
2PM
SAT FEB 23
6PM
N
Collision
Diagram
2007
6AM THR OCT 24
DRY 2007
L
A
N
C
A
S
T
E
R
16
SAT OCT 17
1PM
DLIT
DRY 2008
WED NOV 18
WET 2008
DLIT
7PM
SUN JAN 5
5PM
DUSK
DRY 2008
DRY 2008
DAY
DLIT
DAY
THR NOV 26
12PM
DAY
DRY 2008
THR NOV 26
UNK 2008
DAY
12PM
THR OCT 8
4PM
FRI JUN 26
5PM
DRY 2008
DRY 2008
DAY
DAY
SUN APR 12
3PM
N
Collision
Diagram
2008
8PM THR NOV 12
WET 2008
5 PM TUE APR 23
DAY DRY 2008
6 PM TUE JAN 28
DLIT UNK 2008
12 AM SAT JUL 18
DLIT DRY 2008
7PM FRI SEP 25
WET 2008
SUNNYVIEW
L
A
N
C
A
S
T
E
R
17
WET 2009
FRI DEC 31
FRI OCT 15
DRY 2009
6PM
DUSK
7AM THU FEB 11
DAY
2PM
WET 2009
DAY
DRY 2009
DAY
THU DEC 16
WED JUL 7
5PM
DRY 2009
DLIT
DLIT
4PM
DRY 2009
WED JUL 21
DAWN
DAY
7AM
THU JAN 26
10PM
THU APR 13
DRY 2009
3PM
DAY
N
Collision
Diagram
2009
11PM WED JUN 9
DRY 2009
WET 2009
SUNNYVIEW
L
A
N
C
A
S
T
E
R
18