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TABLE 33 Property-damage-only median opening accident frequency by median
opening type
Median opening accident Median opening
a
Median Number of frequency accident frequency
opening median (for entire study period) (per median opening per year)
type openings U-turn Left-turn Total U-turn Left-turn Total
URBAN ARTERIAL CORRIDORS
Midblock
1a 7 0 0 0 0.000 0.000 0.000
2b 20 0 1 1 0.000 0.010 0.010
2c 10 1 3 4 0.020 0.060 0.080
Three-leg
3a 11 0 5 5 0.000 0.091 0.091
3b 19 5 14 19 0.055 0.154 0.209
3c 2 0 4 4 0.000 0.400 0.400
4a 4 0 3 3 0.000 0.130 0.130
Four-leg
5a 8 0 16 16 0.000 0.400 0.400
5b 17 5 47 52 0.056 0.528 0.584
6a 5 1 14 15 0.033 0.467 0.500
RURAL ARTERIAL CORRIDORS
Midblock
1a 7 0 1 1 0.000 0.029 0.029
Three-leg
3a 4 0 3 3 0.000 0.176 0.176
Four-leg
5a 1 2 2 4 0.500 0.500 1.000
a
The study period was generally five years in duration. However, only four years of accident
data were available for sites in New Jersey, and six years of accident data were available for
sites in New York.
· Most traffic conflicts at midblock median openings and · Median opening accident rates are substantially lower
median openings at three-leg intersections, particularly for midblock median openings than for median open-
directional median openings, were related to the turning ings at three- and four-leg intersections. For example,
vehicle merging onto the major road from the median the median opening accident rate at a directional mid-
opening (Conflict Type C). block median opening is typically only about 14 percent
· At median openings without left-turn lanes at four-leg of the median opening accident rate for a directional
intersections, most of the traffic conflicts were related to median opening at a three-leg intersection.
vehicles turning from the major road into the median · Median opening accident rates are slightly lower at con-
opening (Conflict Type A). ventional three-leg median openings than at conven-
· At directional median openings (Types 2b, 2c, 4a, and tional four-leg median openings. Median opening con-
6a), the greatest problem appears to be related to vehi- flict rates at conventional three-leg median openings are
cles merging onto the major road from the median open- almost half the conflict rates at conventional four-leg
ing, as evidenced by the large number of Type C traffic median openings.
conflicts. · Median opening accident rates at directional three-leg
median openings are about 48 percent lower than the
accident rates for conventional three-leg openings. In
COMPARISON OF MEDIAN OPENING contrast, median opening conflict rates at directional
ACCIDENT AND CONFLICT RATES three-leg median openings are substantially higher than
the conflict rates for conventional three-leg openings.
Table 39 presents median opening accident and conflict · Median opening accident rates at directional four-leg
rates by geometry type and number of intersection legs. All median openings are about 15 percent lower than for
of the median openings are urban. Relative safety compar- conventional four-leg intersections. In contrast, median
isons that can be made from the table include the following: opening conflict rates at directional four-leg median
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TABLE 34 Collision type distribution for median opening turning accidents
a
Accident frequency by collision type
Number (for entire study period) Percentage of accident frequency by collision type
Median of Major- Major- Other Major
opening median road road rear Cross or road Major-road Cross Other or
type openings angle end street unknown Total angle rear end street unknown
URBAN ARTERIAL CORRIDORS
Midblock
1a 7 1 0 0 0 1 100.0 0.0 0.0 0.0
2b 20 2 2 0 0 4 50.0 50.0 0.0 0.0
2c 10 1 3 0 1 5 20.0 60.0 0.0 20.0
Three-leg
3a 11 0 4 4 1 9 0.0 44.4 44.4 11.1
3b 19 8 5 18 1 32 25.0 15.6 56.3 3.1
3c 2 9 1 0 0 10 90.0 10.0 0.0 0.0
4a 4 7 0 0 0 7 100.0 0.0 0.0 0.0
Four-leg
5a 8 16 8 2 0 26 61.5 30.8 7.7 0.0
5b 17 28 33 12 3 76 36.8 43.4 15.8 3.9
6a 5 35 2 3 2 42 83.3 4.8 7.1 4.8
RURAL ARTERIAL CORRIDORS
Midblock
1a 7 0 2 1 0 3 0.0 66.7 33.3 0.0
Three-leg
3a 4 0 3 1 0 4 0.0 75.0 25.0 0.0
Four-leg
5a 1 1 2 1 0 4 25.0 50.0 25.0 0.0
a
The duration of the study period was generally five years. However, only four years of accident and exposure data were available for sites in New Jersey,
and six years of accident and exposure data were available for sites in New York.
TABLE 35 Total median opening accident rate by median opening type
Total median
opening Median opening
accident Median opening accident rate
a
Median Number frequency movements (accidents per
6 6
opening of median (for entire study (10 turns during 10 turning
type openings period) entire study period) vehicles)
URBAN ARTERIAL CORRIDORS
Midblock
b b
1a 7 1
2b 20 4 17.20 0.23
2c 10 5 13.42 0.37
Three-leg
3a 11 9 2.23 4.04
3b 19 32 13.04 2.46
3c 2 10 1.20 8.35
4a 4 7 4.87 1.44
Four-leg
5a 8 26 11.16 2.33
5b 17 76 22.77 3.34
6a 5 42 16.36 2.57
RURAL ARTERIAL CORRIDORS
Midblock
1a 7 3 0.96 3.13
Three-leg
3a 4 4 4.65 0.86
Four-leg
5a 1 4 1.41 2.84
a
The duration of the study period was generally five years. However, only four years of accident and exposure data
were available for sites in New Jersey, and six years of accident and exposure data were available for sites in
New York.
b
Data too limited to be meaningful.
