ST9401-CS 990302MAR 02 '99 01:26PM WIER & ASSOCIATES
MEMORANDUI t
P,2
~UiSjECT:
~like I~1~,rtin
~hilip Graham
~tarch 2, 1999
~}t]ard F~ail Recommendations
~4093
South ol= West Park Entrance:
The guard rail ~outh of the west pad~ entrance can b,~ eliminated with the
sddilional grading tha~ has been done in order ~o construct the sidewalk south to
';:he Ccttonwood Creek Bridge. ( would recommend that 75 LF. of guard rail with
,a 25' terminal .~e~ion be used on the approach to the Cottonwood Creek bridge.
ii:,,iorthw,ast con',er of bridge:
The rrsding and parks improvements made at the northwest corner of the
~'~ac. ton Creek bridge along with the bridge ~'ail extension to be made with the
~,ike and bike trail improvements create a much shorter slope and open flat
;~r'~as at '~he ~,oe of slope. ] would recommend that the guard rail for the
~'~or4'~w~ corne' be reduced to~_~ with a 25' terminal section.
Southeas[ core,el' of bridge:
The siopes along Denton-Tap Road appear to have been constructed
¢~'(ier ;hen [he proposed 4:1. The trees at the toe of slope ,~nd the hike and bike
[~,sil that has f:,een graded st the base of the bridge still present a hazard to a
vehicle twing to recover, however. I would recommend that.,7'~J"~F, e~j:~luard ~ail
with~,- ~uo~-' te,~'min~! section be used at this corner of the bridge~¢~
End of Memq
' ~, ~MAR 8~ '99 01:~?PM WIER & ASSOCIATES ~
HIGHWAY DESIGN DIVISION OPERATIONS AND PROCEDURES MANUAL
P.3
Rev. &84
Offset distance of the area of concern from the edge of
travel lane (including from the ten,ermine markings for
cwo-way traffic operaZions)
Design slope condiclons, i.e. will slopes be lO:l or
flat£er? S~eeper than 6:17
Placement location (alongside shoulder vs. near object,
flared, etc.)
Presence of other nearby areas of concern ~h£ch should
be considered simultaneously.
Once this design data has been asse~bled~ the appropriate char~
may be used.
Figures A-12, A-13, and A-I~ are example solutions using ~he
design charts.
D. Ninimum Length oE Roadside Barrier (Non-Bridge End)
The mlnimma length of NBGF that is located within both of ~he
clear zones of ~wo-way traffic is .75 feet. Post spacing should
be 12'-6" for each 25 feet ad~acent Co a terminal anchor section
and 6'-3" [or the inCerveulng 2~ feet of ~BGF.
The minimum length of MBGF that is located within the clear zone
of only one direction of flow is 50 feet. Post spacing should
be 12'-6" for the 25 leeC nearest approaching traffic and
for the remaining 25 feet.
A-206
BARRIERS ON BRIDGE APPROACHES
For approaches ~o bridges, design chart solutions have been made for
various clear zone widths {i,e., A~T volume levels), shoulder widths, and
for one-way and t~o-way traffic operations. ~inimu~ lengths of approach
NB(iF are sho~n on the Bridge End De,ail (BED) standard shee~s sho~n in
Appendix A-lO0. I/here other hazards are present, longer lensths may be
required as dictated by customized solutions using the design chart.
The lengths shown on the BED standard sheets are for traffic operating at
high speed conditions. For low speed condltions~ ~¥pified by urban street
operations, shorter lengths suffice. For these conditions, it is typlcall~
desirable to provide 50 ~o 75 feeC ol approach. HBGF.~. Access driveways
s']~-~r~~ated beyond'the terminal anchor whenever practical.
A-207
NEDIAN BARRIERS
Section ~-702C in Part IV includes a discussion of median barriers.
Standard sheets ~or median harrier are shown in Appendix A-lO0.
A-77
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