Problem no. 2 Background Information A reverse curve is located on SR-675 in a rural area of DeKalb County, AL between M
Posted: Mon May 02, 2022 11:26 am
Problem no. 2
Background Information
A reverse curve is located on SR-675 in a rural area of DeKalb
County, AL between Milepost 25 and
Milepost 26. The ADT of the segment is approximately 1900vpd and
speed limit is 55 mph. Upon review
of the segment crash data, it was determined that all crashes were
occurring in a reverse curve
approximately 2000 feet long, located approximately midway between
Milepost 25 and Milepost 26.
The curve does not have any Horizontal Curve Series Warning signs
and has not been evaluated for an
advisory speed. The centerline and edge line striping is in fair
condition. All crash vehicles are
automobiles, unless otherwise noted.
Crash Data Summary
Crash data was analyzed for the segment between 1/1/12 and12/21/14
at various points within the
reverse curve and are as follows:
Fatality: 1 total. Single vehicle run-off-the road, at night,
during wet weather
Type A: 3 total. 2 were single vehicle run-off the road crashes,
and one was an opposite direction
sideswipe. One of the run-off the road crashes occurred during wet
weather and the other occurred at
night. One of the vehicles involved in the opposite direction
sideswipe was found to be traveling at 60
mph through the curve.
Type B: 4 total, all single vehicle run-off the road crashes, 2
occurred during wet weather. 2 crashes
occurred at night and 1 occurred at dawn.
Type C: 6 total, all single vehicle run-off the road crashes: 4
automobiles, 1 pick-up truck and 1 heavy
truck. 3 of them during wet weather and 4 occurred at night.
PDO Crashes: 7 total. 2 involved heavy vehicles and the rest were
automobiles.5 crashes were single
vehicle run-off the road crashes (3 during wet weather and 4 at
night) and 2 were opposite direction
side swipe (1 at night).
Based on the crashes, 4 countermeasures are considered:
Countermeasure 1. Install the appropriate curve warning sign series
(W1-4, W13-1p, and W 1-8) with
Type XI sheeting (fluorescent sheeting). Total Cost: $3,700.
Project life 10 years.
Countermeasure 2. Renew the striping and install rpm’s on the edge
line and centerline. Total Cost:
$4,000. Project life 5 years.
Countermeasure 3. Renew striping, install rpm’s, and install the
curve warning sign series. Total Cost:
$7,700. Project life 5 years.
Countermeasure 4. Install a high friction surface treatment. Total
Cost: $122,000. Project life 12 years.
a. Using the CMF Clearinghouse Website (cmfclearinghouse.org), find
the CRF’s for each of the
countermeasures. (4*5=20 points)
b. Review the background information on the site: (9*5=45
points)
I. What do you observe from crash data?
II. Check Highway Safety Manual to see if there are any cmf’s that
you can find for the suggested
countermeasures
lII. If yes, do the CMFs suggest a reduction in crashes?
IV. What crash types will be affected?
V. What are your recommendations?
Background Information
A reverse curve is located on SR-675 in a rural area of DeKalb
County, AL between Milepost 25 and
Milepost 26. The ADT of the segment is approximately 1900vpd and
speed limit is 55 mph. Upon review
of the segment crash data, it was determined that all crashes were
occurring in a reverse curve
approximately 2000 feet long, located approximately midway between
Milepost 25 and Milepost 26.
The curve does not have any Horizontal Curve Series Warning signs
and has not been evaluated for an
advisory speed. The centerline and edge line striping is in fair
condition. All crash vehicles are
automobiles, unless otherwise noted.
Crash Data Summary
Crash data was analyzed for the segment between 1/1/12 and12/21/14
at various points within the
reverse curve and are as follows:
Fatality: 1 total. Single vehicle run-off-the road, at night,
during wet weather
Type A: 3 total. 2 were single vehicle run-off the road crashes,
and one was an opposite direction
sideswipe. One of the run-off the road crashes occurred during wet
weather and the other occurred at
night. One of the vehicles involved in the opposite direction
sideswipe was found to be traveling at 60
mph through the curve.
Type B: 4 total, all single vehicle run-off the road crashes, 2
occurred during wet weather. 2 crashes
occurred at night and 1 occurred at dawn.
Type C: 6 total, all single vehicle run-off the road crashes: 4
automobiles, 1 pick-up truck and 1 heavy
truck. 3 of them during wet weather and 4 occurred at night.
PDO Crashes: 7 total. 2 involved heavy vehicles and the rest were
automobiles.5 crashes were single
vehicle run-off the road crashes (3 during wet weather and 4 at
night) and 2 were opposite direction
side swipe (1 at night).
Based on the crashes, 4 countermeasures are considered:
Countermeasure 1. Install the appropriate curve warning sign series
(W1-4, W13-1p, and W 1-8) with
Type XI sheeting (fluorescent sheeting). Total Cost: $3,700.
Project life 10 years.
Countermeasure 2. Renew the striping and install rpm’s on the edge
line and centerline. Total Cost:
$4,000. Project life 5 years.
Countermeasure 3. Renew striping, install rpm’s, and install the
curve warning sign series. Total Cost:
$7,700. Project life 5 years.
Countermeasure 4. Install a high friction surface treatment. Total
Cost: $122,000. Project life 12 years.
a. Using the CMF Clearinghouse Website (cmfclearinghouse.org), find
the CRF’s for each of the
countermeasures. (4*5=20 points)
b. Review the background information on the site: (9*5=45
points)
I. What do you observe from crash data?
II. Check Highway Safety Manual to see if there are any cmf’s that
you can find for the suggested
countermeasures
lII. If yes, do the CMFs suggest a reduction in crashes?
IV. What crash types will be affected?
V. What are your recommendations?