Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 25
25
TABLE 3-1 States surveyed for establishing availability 3.2 DATA COLLECTION
of data related to PRPM installations
Arkansas Kentucky North Dakota
This section provides an overview of the data collection
California Maine Ohio
and data preparation processes applied during the research
project. To conduct a statistically defensible safety evalua-
Colorado Maryland Oregon
tion of PRPMs in a manner that will provide sufficient infor-
Connecticut Massachusetts Pennsylvania
mation to develop implementation guidelines, the following
Florida Michigan Texas types of data were required:
Georgia Minnesota Utah
Illinois Missouri Virginia · PRPM treatment sites inventory,
Indiana New Jersey West Virginia · Reference group and comparison group locations,
Iowa New York Wisconsin · Historical crash data for all locations,
Kansas North Carolina · Roadway attribute data for all locations,
· Traffic volume data for all locations, and
· Additional delineation and guidance measures at treat-
ment locations.
· The type of marker included raised snowplowable (retro-
reflective) markers. The reference and comparison group location data were
· Roadway types included two-lane undivided, four-lane
required for developing safety performance functions to con-
divided expressway (at-grade intersection control), and trol for changes in safety at treatment locations that are due
four-lane freeways (controlled access). to factors other than PRPM installation (e.g., changes in traf-
· Implementation dates were preferably between 1995
fic volume).
and 1999.
· Crash data included electronic crash data for at least
2 years before implementation and 1 year after imple-
mentation. 3.2.1 PRPM Treatment Sites Inventory
· Other data included accessible roadway inventory and
traffic volume count information, preferably in electronic Electronic or hard-copy sources of the following variables
format. relating to the installations of PRPMs were assembled for
each state:
On the basis of the information received, six states were
selected for the safety evaluation of PRPMs: Illinois (Dis- · Beginning and ending route numbers and mileposts,
trict 8), New Jersey, New York, Missouri, Pennsylvania (Dis- · Date or year of PRPM installation,
tricts 1, 3, 5, and 8), and Wisconsin. Table 3-2 summarizes · Spacing (e.g., 40 ft or 80 ft), and
the PRPM use in these six states. · Placement (e.g., centerline, edgeline, or lane lines).
TABLE 3-2 States selected for the PRPM safety evaluation
State Roadway Types PRPM Implementation Dates Policy
Illinois Two-lane 1994 1999 Nonselective
(District 8)
New Jersey Two-lane 1993 Nonselective
New York Two-lane 1998 Selective
Four-lane freeway 1998 Nonselective
Missouri Four-lane freeway 19922000 Nonselective
Pennsylvania Two-lane 19922000 Selective
(Districts 1, 3,
5, and 8)
Four-lane freeway 19922000 Nonselective
Four-lane 19922000 Nonselective
expressway
Wisconsin Four-lane freeway 1999 Nonselective
Four-lane 1999 Nonselective
expressway
