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OCR for page 31
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Table 3-20 describes the AADT data received and data · Illumination,
sources for each state. For Wisconsin, New Jersey, and Illi- · Rumble strips, and
nois, AADT data could not be obtained for each year of the · Delineation (e.g., chevrons and post-mounted delineators).
study period. Estimation procedures, using the existing
counts, were applied in the calculation of the missing AADT Since none of the data files received from the states con-
volumes. tained information on these additional delineation and guid-
None of the data files received from the study group states ance measures, the research team followed other data collec-
contained information on the percentage of annual average tion strategies (see Table 3-21).
nighttime traffic (i.e., annual average traffic between sunset Tables 3-22, 3-23, and 3-24 show the percentage of two-
and sunrise). Permanent traffic counting stations (which col- lane treatment sites with and without illumination, additional
lect continuous annual traffic counts) and average monthly delineation (e.g., chevrons and post-mounted delineators),
sunrise and sunset times were used to estimate the percent- and shoulder rumble strips, respectively.
age of annual average nighttime traffic at the various road- The states reported that chevrons are not placed on four-
ways. lane freeways and expressways. However, post-mounted
delineators are placed along freeways at a spacing of 60 to
100 ft (18 to 30 m). Less than 1 percent of four-lane freeway
3.2.6 Additional Delineation
and Guidance Measures and expressway sites are illuminated.
Tables 3-25 and 3-26 show the percentage of treatment
Information was collected on the following additional delin- site length with and without shoulder rumble strips for free-
eation and guidance measures: ways and expressways, respectively.
TABLE 3-16 Summary information:
environment type at four-lane freeway
treatment sites
State % of total % of total
roadway length roadway length
(urban) (rural)
Missouri 19.1 80.9
New York 32.1 67.9
Pennsylvania 29.7 70.3
Wisconsin 12.6 87.4
TABLE 3-17 Summary information: lane widths
at four-lane expressway treatment sites
State % of total % of total % of total Minimum Maximum Average
roadway roadway roadway lane width lane width lane width
length when length length when (ft) (ft) (ft)
lane width when lane lane width
12 ft
= 12 ft
Pennsylvania 11.0 78.9 10.1 8.0 25.0 12.4
Wisconsin 0.0 97.2 2.8 12.0 18.0 12.0
TABLE 3-18 Summary information: shoulder widths at four-lane expressway treatment sites
State % of total % of total % of total % of total % of total Minimum Maximum Average
roadway roadway roadway roadway roadway shoulder shoulder shoulder
length length length length when length width (ft) width (ft) width (ft)
when when when shoulder when
shoulder shoulder shoulder width shoulder
width width width > 8 ft and width
4 ft > 4 ft and > 6 ft and 10 ft > 10 ft
6 ft 8 ft
Pennsylvania 54.0 6.1 21.3 8.9 9.7 0.0 12.0 4.8
Wisconsin 0.4 1.6 73.2 19.8 5.0 2.0 13.0 8.5
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TABLE 3-19 Summary information: TABLE 3-23 Percentage of two-lane
environment type at four-lane expressway treatment sites with and without additional
treatment sites delineation (chevrons or post-mounted
delineators)
State % of total % of total
roadway length roadway length State % with % without
(urban) (rural) additional additional
Pennsylvania 18.6 81.4 delineation delineation
Illinois 1.0 99.0
Wisconsin 11.6 88.4
New Jersey 1.0 99.0
New York 26.0 74.0
TABLE 3-20 AADT data and sources
Pennsylvania 7.4 92.6
State Information Received Source
Illinois AADTs for 1991, 1992, 1994, and 1997 to 2000 Highway Safety
Information System TABLE 3-24 Percentage of two-lane
(HSIS)
treatment sites with and without
Missouri AADTs for 1991 to 2001 Missouri DOT shoulder rumble strips
New Jersey Short-term counting station data (downloaded New Jersey DOT
from Internet)--various years State % with % without
rumble rumble
New York AADTs for 1991 to 2001 New York DOT
strips strips
Pennsylvania AADTs for 1991 to 2001 Pennsylvania DOT
Illinois 0.0 100.0
Wisconsin Traffic count books for 1995, 1997, and 2000 Wisconsin DOT
New Jersey 0.0 100.0
New York 0.0 100.0
TABLE 3-21 Additional delineation and guidance
measures: data collection strategies Pennsylvania 6.6 93.4
State Data Collection Strategies
Illinois Undertaking field visits TABLE 3-25 Percentage of four-lane
freeway treatment sites with and
Missouri Contacting DOT staff without shoulder rumble strips
New Jersey Reviewing video-logs
State % with % without
New York Reviewing video-logs rumble rumble
Pennsylvania Reviewing video-logs and contacting DOT staff strips strips
Missouri 53.1 46.9
Wisconsin Contacting DOT staff
New York 63.3 36.7
Pennsylvania 37.7 62.3
TABLE 3-22 Percentage of two-lane treatment
sites with and without illumination Wisconsin 100.0 0.0
State % with presence % without
of illumination presence of TABLE 3-26 Percentage of four-lane
illumination expressway treatment sites with
Illinois 7.1 92.9 and without shoulder rumble strips
New Jersey 42.0 58.0 State % with % without
New York 26.0 74.0 rumble rumble
strips strips
Pennsylvania 0.0 100.0
Pennsylvania 21 79
Wisconsin 100 0
