xt71zc7rqx87 https://exploreuk.uky.edu/dips/xt71zc7rqx87/data/mets.xml  United States. Federal Highway Administration United States. Bureau of Public Roads United States. Federal Highway Administration. Offices of Research, Development, and Technology United States. Federal Highway Administration. Offices of Research and Development 1940 v.: ill., ports.; 30 cm. UK holds archival copy for ASERL Collaborative Federal Depository Program libraries. Call Number FW 2.7: 20/12 journals English Washington: U.S. Federal Highway Administration etc. Contact the Special Collections Research Center for information regarding rights and use of this collection. Works Progress Administration Transportation Publications Roads -- United States -- Periodicals Highway research -- United States -- Periodicals Public roads: a Journal of Highway Research February 1940 text Public roads: a Journal of Highway Research February 1940 1940 2019 true xt71zc7rqx87 section xt71zc7rqx87 - . .~, I ~"' ' ,. 7 ‘ ’ M " ‘ 7-; ‘* FEET.” ’ ' ' ' ' M ., ‘ ‘“ ‘ “"—‘ ‘ ’ ’ " , 1““.{1
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A JOURNAL OF HIGHWAY RESEARCH ' I"
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VOL..20, NO. '12 V FEBRUARY 194-0 IVII
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13" TRAFFIC DURING A STUDY OF VEHICLE PASSING PRACTICES II 1
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PROGRESS IN S l UDY OF MO I OR-VEHICLE I I
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I “ PASSING PRACTICES ' I '
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I BY THE DIVISION OF HIGHWAY TRANSPORT, PUBLIC ROADS ADMINISTRATION . III I
‘ 2 Reported by 0. K. NORMANN, Associate Highway Economist ‘ IIIII
.2 ‘1: I212
‘ NOWLEDGE of the manner in which highways Tabled shows that 57.3 percent of the passings were IIII
, are used is a prerequis1te to improvmg their design accomplished by multiple maneuvers although there izIII
If so that they Wlll more adequately serve highway were only about half as many multiple >maneuvers as II
I users. A study of passmg practices of motor vehicles is there were single maneuvers (one vehicle passmg two I I
2 part of a research program recently initiated by the other vehicles accounts for two passmgs). These '2-
III» 1; Public Roads Administration to supply information on figures illustrate the importance of including in a study , ,-
‘ the normal drlvmg habits of. vehicle operators. ' of passing distances and practices a study of multiple— '3 i
“I 2" During the fall of 1938 studies of the passmg practices passmg maneuvers as well as single-passmg maneuvers. III
(f,- g of motonvehicles were conducted on four sections of . I,
"’1‘? highway in Maryland and Virginia with special equip- TABLE 1.-Types Of passing maneuvers observed (average trafic E I
merit developed by the Public Roads Administration. ””Iume 375 ”ehwles 106” hm”) II I
. “ A report describing in detail the methods‘and equip— M . P . ‘ ' I: I
- Q merit used, and the purposes of the passmg-practice Typeofmamuver I ‘ 5:333:2ch 85531123135001“ I.
,2“ studies, has been published.2 _ ' !—-———~~—2————~-~———-~#————-vs —~e~——~ ——-—————-— I II
‘,_ In cooperation with State highway officials, studies Agum- P t 125m:- P I I
were conducted during the summer of 1939 in Massa- snare LIIOG item) 138596 ”463.1% I I
2 chllsetts, 0,1110, and 111111018, and studleS; are now belng M“I“,QI§,},,,passmggvehms 1,, ,,_, 362 1,, j:
; conducted in Texas. The program also includes studies §YogicIcspassing;yghilclc.__.n_,_:___,.., , 16; 2.8 322 12.2; 'I
I '12} California and Oregon neigt spring: Upon comple- 2lthifiifispéiié‘g‘fig2‘3et‘gc‘225::::::::::::::::.: 32 '22 I33 3:? ‘ II
: tion of the fieId work, data will be available for normal . If:32;gIgsrggggfggfllt50,393,315;*~-~----—~~ 3? {:3 ,2?) g”; ’, ,'
jg: f passing practices under a Wide variety of road condi- ‘2‘iehilcles passirifIIStoavehicles::::::::: 135 .3 102 4.0 I I
3."). 2, tions, geographically distributed to include any major “I 0””mun”)epass‘ngs"""“”“'“"‘"’ 18 .__ 1'1 S_99 _ 3.19 f I':I
.7 I differences in driving habits. TOWmUItiI)I0~-»-—-------vu-~--umv 539 33-0 1,408 57-3 ,
There has been so much interest manifested wherever Grand total 12635 100.0 2,564 100-0 I I
. the equipment has been in operation that, in addition to M 'II II .
C, j supplying most of the personnel for the field work, dif— Th _ t . ‘t t It 1 . ‘ I. II
”"5: :ferent State officials have felt that the information elniosnmpm an ‘mu .lp e—passmg maneuvers ale II
. 72:; 3 obtained will be of such immediate value to them that £11058 lflyihmh $1116 vehicle 6mg? passes 0,: 1? plassed Ib'y II II
2 ; they have desired to supply the personnel necessary for W0 V6 10 es. ey compose '5 peicen 0. t e mu tl' . I .I
2 :3 a a complete analysis of the data. ple maneuvers and 46.6 percent of the passmgs accom- 1 I,
Several improvements have been made in the equip- plished by multiple maneuvers. Three yehicles passmg I} I,
2.) 2‘ merit to reduce the time required to install it on the fourvothei vehicles was $131110“ complicated multiplej III II
=-’ ‘ study sections and to permit operation at night and on PaSSFIIg maneuver recor e_ ' 1,1: I
ML," I rainy days. The most important improvement has Figure 1 shows, for various hourly volumes, the per- . II 2g,
I“, I reduced the amount of work required in transcribing centage .Of the total number Of maneuvers and passmgs I?‘
i .2 the field records. This is the major item of expense in “0011113115th b3; multiple-passmg maneuvers. At an II 2
Ly, i? the studies and has been reduced to less than two-thirds houily t1 aific V0 ume Of 200 .V' 611101632 35 percent 0f the ' If? '
24):, of its former cost total passmgs were accomplished by multiple maneu— v»,
riot“; The detailed data'for 1 635 passing maneuvers re— vers. At traffic volumes above 450 vehicles per hour, ‘,‘
‘ ' ' / ’ - a this figure exceeds 60 percent. I
Ia? corded during 37 }2 hours of operation on the four study . h h b ,_ f ‘ 2,- ,
i sections in Maryland and Virginia are now ready to be Figure 2 S 0W5 t e average num CI 0 maneu‘veis and 1 HI
placed on tabulating machine cards prior to starting passmgs observed perhour on the four half—mile study , I II
“h'fj ' the comprehensive analysis. Although these 1,635 sections during various hourly trafiicvolumes. AS ex- I
I passmgs are but a small portion of the total number pected, there IS a marked increase in the number 0f I “I
Int}; 1, that will be obtained during this study, they will be passmgs as the volume increases. These are the num— I III
Ml: I; used to illustrate the method of analysis and some of Ber offpassuigs actclongplisheicI 1161‘ 1101f: and n03 thle IllumlI - II
3;; I the facts with respect to passing practices and driver 31.0 passmgs ‘13 WOU C. lave een ma e “u a I2I
scat , behavior that are being obtained vehicle operators that des1red to pass been able to . .’
’ “:7. ' make passmg maneuvers. . ,g.
" OVER- HALF OF PASSINSENéfig‘EII‘gLISHED BY MULTIPLE One. vehicle usually passes another vehicle because I7 II
3.3", . the driver wants to travel faster than the other vehicle 2 II
ng. The first class1fication of the passmg inaneuverswas is movmg. Within the lialf-Irnle study section it was I II
-ur-I made by separating them into the single- and multiplc— generally poss1ble to determine the speed that the driver I I I
I 2 Passing types. In the single-passing niaiieuvers,‘one of the passmg vehicle desired to travel. by noting his II I
”if: Vehicle passed one other vehicle, while in the multiple— speed either before slowmg down prior to making the II I
' passmg maneuvers, two or more vehicles either passed passmg maneuver or after the maneuver was completed. ,I ,
—-‘; or were passed b one or more vehicles. Table 2 shows that in 55 ercent of the assings the I ’
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IPaper presented at, the Nineteenth Annual Meeting of the Highway Research passed VBhICle “Yas traveling from 31. I30 40 miles per I I
BIaIE‘IICRE‘COIIIIIPF It] 19:39], A I" P . 22' 2 ru 1 'V‘1‘1s I E hour. The speeds of_the passed vehicles in nearly all 3
H.HolihoéIrI’U‘IIIIIIIIJITcdilaigflddlinfih1313.111]?.liliiiiuiigrsfhda. 0 m ”we" Iy ‘ of the remaining passmgs were almost equally distrib. 2
_ 205032—1r)u—1 221 I I
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* , _ . ' ‘ I II

 V,, ‘ ' ‘ Vol.20, No.12 February 194° _
W M PUBLIC“ .- III. 5°
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" * .0 I-Iilllll-Il-Il 4° “II-“lull...“-
‘1'] \ II... 0 A00 500 600 70 20 ‘ Ii“. 400 500 500 700 800
f1 ' ‘ O 200 30 PER HOUR 300 R
5‘ ; I00 - vEHICLES o loo 300 ES PER HOU
H» v 1 ° ToTAL TRAFFIC VOLUME MANEUvL‘RS ANI: 0 AL TRAFFICVOLUME _ VEHlCL D PASSINGS
«L L TOTAL PASSING MUmIPLE TOT MANEUVERS AN
1H ; D 1—PER0ENTAGES 6)ng ACCoMpmngzngEs 2 TomL NUMBER OFV MILE STUDY SECTIONS AT
_, 1 ‘ FIGUR‘ - THAT AFFIC ‘ . URE ,— " HOUR 0N 2'
\ 1 ssINGS ous TR FIG PER , a _
t J L TOTfigGPll‘i/IANEUVERS AT VARI through 50 ACCOMPLIfirfifliLY TRAFFIC VOLUMI‘S
I" 11 PASS through 30 and 41 VARIOUS S that the left) lane W85
3‘ _ ‘ en the 21 - . table 4 show f et in 27 perqent
, ‘ 1 uted betwe fthe drlveI‘S _- lt—hilnd lane, than 500 e . ' hll
t" ‘ ‘ l mile-Per'hour lgroulligtvs that 51-4 Percelit 0']es per hour liggr for a distance (if ie‘ihere Was an Oncorilllng nggse
“ W ' - SOS than 1. m1 . d Ce - ndt a toft epas '
I ‘ E I % Thls table a - 1; travel less d 1red spee t1 e passlngs a - 16 8 percen « . h' 16
. .g ‘ 3 d desu‘ed 0 . d that the es of 1 _ 0 feet away 1n ' - . h the passmg V6 1_C
"" “at t i that passe d vehlcle an . hour faster- than 00 - n whlc n
, 1 asse 3 per . less assm‘TS 1 . b oncoml g
a it ; faster than the p 1 than 6 me dlfl-‘erence d‘lta for the P . 0 th fight, lane 3’ f 1
. L t was 635 . the average . The v back mto e 2: t be very use 11 fl
1 t . 21.2 percen se 1n . desu‘ed _ f, forced . - may 110 26
a 3 of . 1. d decrea d the as no . d stance . b t they
‘ t It mane d vehlcle an d W - ted slght 1 . dlstances, 11 _
‘ 6| u There 1s a d of the passe d of the passe traffic or 111111 . . m paSSlng . stncted
w ‘ the 81366. ' 1 s the Spee dis— . . - incr nnnlmu - dumng unrq
: +131 -1 between veth e a . f ueTle - detelmm b - ' ractlces , ted as
assmg . the req 1n 1 dnwng P unrestrlc
I‘ F ‘ Speed Of the p Beslde Showlng - these data in Sho‘v actua _ tiCeS durlllg‘ hen
5: E 1 ' ‘ reaseS- sed veh1cles’ ~ htl W - - Drivmg prgq t be known W. 50
;, : w - Vehlcle 1110 eedS 0f pas 1 at 3, 811g y ndltlonS- d1t10115 mus . . U hablts
- t I \ - ' n of the Sp - c to trave 5188 CO tFiCted COD rmal derlnb m
4% g4 \ tnbu'filo d 'verS desnlng 1d rather P on as 1‘98.- 1: fit the no :> _
K a ‘ « . . that r1 . head wou . ts W _ . hways O 0 1.5
, - ‘- dmate Vehlcle 51 resell nmv hlg , I
”f 1 higher Spifid $351113: when “1119 fgfpflfinslgypbehmd- ifsiimcfi operators‘ k- single-Passmg We; Em
; , 111g - d 5 1g y - l 3 ma my rage in! 0 a
l‘. the prece thelI' spee of 99le e . ass (ave h,
, _ , uce , _ ~centage 1mg to P
am Itself than red - ed by the speed 01‘.th passed TABLE 5;” 112% delayed 11%;)? SW €35
‘ '3} . - 7‘ .. ' I
It ‘ ‘ Single 2,1133an? classlfd 0f the passmg vehw e Zilume 870 vehwles P67” 0
M 1E ‘ TABLE 2—, the deszred 3106 m u so
I it: I vehwle and m _"# by {II- t by 1311;z Total E @
_. ‘l ‘ ‘ . . - 1 mu m
_ NE ‘1 1 '—————_—Speed of passed Vehlde—E—L—_— sugzchtce 312:1?ij In 25
1" {I i { 15mg vehicle —*““———- r Over Total dxs an __.——
M g D Sim; speedo D~ gr ster than K d _ 31-40 4H0 50 _ —— Pg an,
L‘ l; i ; :11 mdflgsf Sggsgglirlolficle $131; 21 30 _ __._————~ —‘_—-_________.__ PerceTgO Pages??? r53~7
't‘ i spee __—~——"—’—— ”6—”! percenl Per“?! ”gig H— d as vehicle to be passeg- 1 ' 9 4 16‘0
MI 5 ’ ————“__W# Percent Pe’f’gt 1263.2 g? 073 30‘? slowed down togflfigfims perhour°‘_§1}?_53?‘i.. . 6'6 ' 147
'h‘ [l ? A 4.0 18% 5:5 ‘3 333;; sxoweddovgfifg’to beDaSSeq-firfi’fi'fiifés-berhour“ 3.9 5-8 __‘_
‘ “I w } 5and underuu-fl ..-—7~""" ""6—4 6-7 17"; .8 .-—-—-~' 52 of the vewn but not to Witdl __,.»-»-»--""' ___\____——0-9— $4.4
:1 1‘ t 3, (3—105——»-»-""'":‘_:__..A-A----' :7 3-3 if, i '1 .7 Slg;%%%?vefiicle to be passe _._..— 33~5 5 '__ 15-6
1 3 ‘ “"1 .3 " :1 - ___——- . t'ng maneuVCF--"”::::: —__
N1 $ 5:33:iii—r--—--*~-"j:ii2iil -3 _‘2—5—0—7; LO 100-“ ngttége‘fflvifiefi‘EtSEi‘irn‘gmaneuV°I--""" ‘.':W‘ 10‘”
3“ ‘ I bver 30 "77 20.7] 3- Tota '1 " __—
‘ E K 1 _‘_,_ -
*1 A {) Tnm‘»-----"""'"~ . , h-dc (miles per hour) that
t 1 t 1- “passed and pussmg ‘e ‘ fiould 3“ d
:‘1 “I: ‘ 1 Wm Distance that driver; of iigzigngnaneuver was sample“
l‘ 13,1, ; __d—IW—FM—W Tgfggamas hegmtzzzs how #4
t i Y E ‘ I —’_—— ' vo ume
, ' ‘ . - e trafiic . .
t t! 1* ‘! ____.—_._ t aceomphsh Smgle (“03mg sightd|5:t_ (193$; Total %#
j i i l - that were able 9 t ble 3 Shows We“, 25 3‘
f' J H ‘ 1 Of 3:11 the drlvers the Study 5601310115: 3 the could Di‘tauce that leftlaue was clear mg [ac ______.
‘ I “1" V - maneuvers 011 1 down before y - ‘ 11 h ———'—_’_—-—— Percent percefll
l: "1‘ passuéfi 4 percent had to S 01W d down to Praetm y Pe’ci’s‘z 16‘8 £3 F1
"' i>“' ‘ ' . 0W6 ' to 132158, _‘—-—-———— __ , ' 16.0 ’
‘M . 1 tha’o . .7 elrce11‘0_S re 0mg . 19.0 _5 39.0
E‘W? ‘ start to pass, 53 the Vehlcle they Weh' g5 mlles per Lessthanooo 30'5 —7—"’n S' ilar data
‘ w 6% the Same speedt asslowed down 19(1) Wtfl: grilwere going to 500 t°llb%%°‘"I:II:"""N—"flmw" W 40'3 100' neulvlzlrs record
i't‘ and 16 peltGen f the vehlce e and stay 0"” ’ r . - d 4
‘ t “‘5 M speed 0. slow down t Totfll..---"""“_- RS ‘ll'glflla: an
M. u hour of the th rd had to . ]d see tha MANEUVE ' the 1V1£
‘ E About one: 1 - untfl they 0011 to m durmg_
'1‘ '! M gafind the Precedlngi: V821gfifficient distance lal‘lifgiwn LUSTRATION OF DATA OBTAIND 1 ssin" maneuVeI‘ f“; tlfmt th1.s mug/‘1'
,_.. “ e 1 01- , d to s 0 IL . 1 pa 2: tlIl 1n 5
. w ear tha f r eac Sen 0 pass g
,_ , d was 0 9 ercen thev . banned 0 . - ch repl‘e
: l the 1‘03 {153 and 50 p. 2158 before ~ The data 0 9 molllSlVe’ ea ' tances; scheduled field
; lli : i E It them to P I - (3111019 to P 15_6 fi ures 3 t0. _ 1 eedS dIS .
‘ . ;-\ . erml , ncoInlIlg V The other - t, ated by g s A1 SI) ’ 111016 a r to be 1
iii? ~ p d walt for all 0 - aneuver- . tart- 111115 1‘ ritical 13031131011 ‘ - - Of each Ve ppea’ .
‘ 5“] ‘3 an the passmg m d wn p1~1or to s e of seven C 1 tive posmons 'n these r'resses W111 be
. n, :1 start ' to slow 0 down on - 1 and 1'0 a - shown 1 °
. In ‘ Cord-d t requll'ed had to 510W ' mteI'Va/ SJ vehlcles as f I' one maneuvers t0
3 .t ‘: ; nt were 110 a have the tune the other a sheet 0
1| il‘! Efécghe maneuverfl] Tfigngtlnyer but they started wlth “59:3: Egbtained from the dat
z: letino' e _ fi ures W ,
I [Hi after 033% that normal speeagéing vehicles had 003116 pissing maneuvel~
‘ l ”W“ maneu the drivers 0f the P and returned to
a \ ‘. ‘ When - neuVers
!_ t t t ; i h aSSIDg ma
t t 12’; ,1: 1318th t e I)
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, . (I I
‘ II I
. I:
L I
12 WWW 1940 _ P U B L I C R 0A D S 223 I II
= HEP—fl I ‘I
so 50 I I
a o Is
L — LL.
3 i I‘
5 35 o 6 0 55 [VIII
f @\-____._______.___\ /__
:30 ~ ‘9‘ 6 “ "\--~-- 9 __,../..- " 3° III
5-, e *"—' , I I
25 25 .I I I
POSITION I N0. 3 STARTS T0 ACCELERATE ‘L
I66 FT. I I
GS II
LL — a I
E) D D III.
13 . LII
1t 88 FT —I III ,
1e I I20 FT. I I I II
‘S. V————— SIGHT DISTANCE = I,325 FEET ——————I ‘ II
16 II
1g I I
uI .-__ . LII
ay 26 24 22 20 IS I6 14 [2 IO 8 6 4 2 0 I I
3d STATION I .I
as FIGURE 3.—CP.ITICAL POSITIONS AND SPEEDS OF VEHICLES AT START OF PASSING MANEUVER. I I
an _ L
ts 50 50 I I
g I I
, 21.5 e 45 I I L
Iu— 5 L I
W H W "° ‘
w o i I
_ €35 .9“ \V w 35 ' "I
Lal 33° — “ ~_\_. 0 ___’__,/- " so I I IL
t2 @ 9 e L I II
__ 5 25 I III
I L
:I L
$3 POSITION 2 (L7 SECONDS LATER) No.3 MEETS ONCOMIN‘G VEHICLE III II
. LL} II
4.7 II II
LL @ I
Q s) r; o 1 I I
_ I I
hat 74H. ® . 2 II
:19 d IZBFT. III
# SIGHT DISTANCE = I,227 FEET L 1' iI
I31 I III
— 26 24 22 20 IB l6 u. I2 [0 e 6 z. 2 o g III
III STATION L . E
323 FIGURE 4.— CRITICAL POSITIONS AND SPEEDS or VEHICLES AT SECOND STAGE OF PASSING MANEUVER. ‘ j I
; L.
00-“ Similar data have been compiled for the 1,635 ma- type of maneuver at a series of speeds for each available I I-I
“ IIIUVIers recorded on the study sections in Maryland and road condltion. _ . . . I I
ms I’lrgmla and also for 500 of the maneuvers recorded . Figure 3 shows the posrtion of each vehicle that IS I I;
are Innng _the Massachusetts studies. It is not intended likely to affect the manner In which the passmg ma- . I
Ing that this much detail be Obtained for all the thousands neuver 1s made. At tlus Instant, vehlcle N o. 3 starts "I
_ es If passmgs that will have been recorded When the to accelerate In order to pass vehicle NO. 2 and poss1bly I-f I,
’clei SBheduled field work is completed, but the factors that the four vehicles ahead of Ivehlcle NO. 2, the closest ,‘
ese IPpear to be the most important as the analysis pro- one bemg vehIcle No. 1, a distance Of_ 120 feet ahead of . I I:
me Hesses will be taken from the field records for enough N0. 2. All dimensmns between vehicles represent the
IIlaneuvers to obtain a representative sample of each dlstances between the front of vehlcles. Vehlcles Nos. I
III,»

 11: .111 1 :1 V . ;»—,—e—:1 A\, ~ ., _ __;,A,.,_ 11-» .-._. .77.._—. ~-» -—- 111 - " ~ —- - - ~ - ~— 4 11 11 ’ ' "
:1 11‘ .
1111
i 1 224 P UB L 1 C R 0A D S Vol.1) 1 1.111111111114211
11 1 1 .ho. 12
111 1 50 5° 50
1! 1. g g
" 1111 $45 9 15 gas
1111 1 I1 0: [Z
11111 1 11: g 10 _ o 9 10 195110
11111 8 k 5
“‘1 ‘I b \_ ‘5 “5
1 11 '11 '8 30 » '—-—_ e 3 IS 30
11 A ‘ E 9 0 ° 5
I I1 m 0 9 "I
111 1 1 25 25 25
111 1 1
‘1 1 1 1' POSITION 3 (I I SECONDS LATER) No.3 ENCROAGHES 0N LEFT LANE
1 1
11 1 nan
1 1 :1 , v
1.1 _» ..
.I 1:1
1111 '11; 63 FT
1 11. 1 I33 FT.
1 1 1111 ‘ ——— SIGHT DISTANCE = I, I75 FEET ——
1 11 :
‘ . 11 1
.; 1 : ___
1 \11 Wm
‘1 1 1 11 26 21, 22 20 :3 us :1. :2 :0 a 6 A 7. o 26 2
11 1 11 STATION
1 1 1 ‘1 FIGURE 5.—CRITICAL POSITIONS AND SPEEDS OF VEHICLES AT THIRD STAGE OF PASSING MANEUVER. :
111 | 5°
1' I1 1 - so so n:
1111 11 g 3
1I: :1 e e 1 1:"
1 ‘ ‘ c: w
11.1 . 1- 1 —
11:1'1‘1'1: 2 1° 0 1° 3
1:11 1? sash. e 9—” €35
III: 1 I I.- w ,, -- ‘5 a @
‘ :1 1. e 3., _ "”"’ “““\~— 9 —-/' 53°
.1 : w e ‘\-~~-_-._.;--—’—-/ 1° “1
11111 1‘; 1 .5 ' 1
111111 1‘
11; 1'11 . 1‘: POSITION L (2.7 SECONDS LATER) no.3 ENTIRELY IN LEFT LANE
1
1111111 1 ”.5”
111‘ 1 1 37 FT.
( 1 1 1,1 1 \
111 1'1 1'1
_l- E
111:; — ..
11:11;
11111111 SIGHT DISTANCE = 1,025 FEET —'—"1
1 : 1.‘
1 111:
1 1 1- 11» I
~ 3‘ 1
11111! 1 '
1 ' 1111 1
‘1 1‘ 1 1 ‘ .__.__—1_______1______,__.—1_____.—.—-_____I—.—.____‘1 ’
1 11111 as 21. 22 20 :3 I6 :4 12 lo a 6 4. 2 0 as ‘
111,111 1 STATION '
1: >111 ' FIGURE 6.—CRITICAL POSITIONS AND SPEEDS OF VEHICLES AT FOURTH STAGE or Passmo MANEUVER. 1
‘ II 1 _ . . . . . . 11
1 1 1 1 4 and o are oncommg vehicles In the opposmg lane of required to slow down to 31 miles per hour, the 5111' {finelfiilttvgfii
1 111 1 traffic, No. 4 being the vehicle met by No. 3 before proximate speed that No. 2 has maintained. (T511919 indicates that
1 1 ‘111 encroaching on the left lane, and No. 5 being the first 3 indicated that 53.7 percent of the observedpassmg 10 ass e Ien‘
'1111 oncoming vchlcle met by No. 3 after completing the maneuvers were started after the passmg vehicle had 1111 ‘ the‘ secl
1 1:1 maneuver. The spacebetween No. 4 and No. 5 repre— slowed down to the same speed as the vehicle to be and shown b‘
11 j ‘1 sents the “hole” available in the opposing lane of passed.) 1 1 . 111.8 arallel' l
1. 11 1 traffic. 1 The data sheets for another passing maneuver Indl- Midlisno 374
1 1 11:11} At the top of figure 3 Is shown the speed of each of cate that vehicle No. 1 has just finished passnig N93 ate] aftevi‘r th
1» 1 11‘ the five vehicles over the portion of the study section and has also slowed down to a speed of about 31111116S hflslns first (
1 1 11111111 ' traversed up to thls pomt. Vehicle No. 3 entered the per hour. Vehicle No. 4 is approaching at a speed 01 hindrance f“
' 1'11 1 section traveling about 40 miles per hour but has been 31 miles per hour and No. 5 at a. speed of 42 miles P91 -
1 11:11 1 1 being out of s
1111‘
1 111111 1
1 i 11:.‘1
l ‘ 11|11111'
1 1 ’11.
.111 (:11. k ‘

 4 . _ 1 7'" 7"" """“"""" '—"”""‘“—"” V“ ""‘“‘"“’"‘_‘1;71
5
.2 February me P U B L 1 C R 0A D S 225 311
; /’———————~——————#—*———/’——”—‘—r—~—r—T———“——“‘——”“— 1
3 50 5° '71
g 9 I I'
5 i "5 9 [*5 WI 1
I! E ‘ 1
w L I ‘
° 1.. K. 0 4° 1'11
u 1 I
. e‘wg” 1“
I 1 ! 1
a 30 1 w 1 1 1
3 W 9 \'~\..‘ 0 __’___’__ 30 1'1 1
.11
5 25 25 1 ’ 1
POSITION 5 (2.9 SECONDS LATER) No.3 EVEN WITH PASSED VEHICLE 111
1.
(a s g 1 11
— 1. D D D 11
I: 1
IAJFT a 111 1
1 S‘IGHT DISTANCE = 71.9 FEET I1‘ 1'!
1 l
I 11
2W 11
STATION 1.1
FIGURE 7.—CRITICAL PosITons AND SPEEDS or VEHICLES AT FIFTH STAGE or PASSING MANEUVER. } 1
' 1
50 50 ' [1
O n: , 11
g 45 0 9 1.5 1 1f
1‘” kw "° ‘ 1
O U
5 g 35 \ o 35 111
1 ‘ 3
§ 3° “w”- :—\'“T—@——.Z‘/ " 3° 1 1
1 11 ® 9 “we", I ,1
POSITION 6 (2.7 SECONDS LATER) N0 3 STARTS To RETURN To RIGHT LANE 111
<23 1‘) (e 1 .1
_1 .
, o 1 1 L
43 FT 1 11
' IOSFT. 1 11
I 11
SIGHT DISTANCE:4I6FT ‘ 111‘
531
1 'I‘
;__J_—__A—_L——L____|_—_|__——l———L——L————i——L——-‘# 1 11
as at 22 20 15 I6 I1. I2 I0 3 s a 2 o 1 11
STATION 11
1 FIGURE 8.—CRITICAL POSITIONS AND SPEEDs 0F VEHICLES AT SIXTH STAGE OF PASSING MANEUVER. j 1
1 . . . . . ‘ 1
RP‘ ‘hour, but No. 5 cannot be seen by vehicle No. 3. The 1 In the third pos1t10n, occurring 1.1 seconds later and 1
.ble fact that vehicle No. 3 starts to accelerate at this point shown by figure 5, vehicle No. 31first encroaches on the 11 9‘1
i112 Indicates that the driver has already decided to attempt left lane while 63 feet behind vehicle _No. 2 and traveling 1 :1
11111 to pass even though N0. 4 is still 166 feet away. 7 miles per hour faster than the vehicle to be passed. 1
be In the second position, occurring 1.7 seconds later In the fourth position, taking place 2.7 seconds later 1, ‘11
and shown by figure 4, the fronts of No. 3 and No. 4 (fig. 6), No. 3 is entirely In the left lane for the first 11 1'
“11. are parallel; No. 3 has accelerated to 36 miles per hour time and is still 37 feet behind vehicle No. 2. 1 In the ’1
)_ 2 1111(118 now 74 feet behind vehicle No. 2. It is immedi— meantime vehicle N o. 2, which has been traveling at a
iles ntely after this instant that the driver of vehicle N0. 3 uniform speed throughout the first 990 feet .of the '
1 of 1111s lns first opportunity to enter the left lane without section, starts to accelerate. The driver evidently w
p91. hindrance from oncoming traffic (vehicle N0. 5 still does not like the idea of being passed or unintentlonally 1
being out Of sight). steps on the accelerator. He cannot accelerate very 1 I
1 ‘1 1

 :11 " ‘ 1 ,
11 1 226 P UB L I C R 0A D 5 17012011110112 -. F-ebmry 19110
' '11 " 1 \\ é
1" ' 2'
CL AR I A1
1.11 1 ‘5‘ 1.5 e 6 15 '8 “.3133.
11111.11 0: 1+0 " ‘9 “*———“"——“—"__—‘-- 40 211, 1:15TART
'1' 1 31' 2 12
111 . . V A "‘ _. __ m
1 g” @ ./ e 0 \'-~--——--@"’ . °° 5:
1111 5% 25 _./-- (15" 25 . ———
111; 1 ‘ a. o
.11 .11- 20 o 1 z a
1 1
1 1 1‘1 POSITION7 (2.6 SECONDS LATER) No.3 BACK IN RIGHT LANE FIGURE 10.4
1‘ 1 1 VEHICLES C
.1 1 107 FT. cOMING TR.
11" 1. LANE DUR
1'11 ‘11 ‘ VEHICLES ’I
111. —efi -
11 11 75“ combination
1 3 appears in n
' 11 1 85 FT 111 break—dew
' 1 1 11 will permit
.1 .1 11 , to be obtaiI
11 ' 1 IN LEFT LANE ONCOMING VEH|CLE TRAVELED passings thz
1‘1 111 650 FT - no.9 SECONDS 562 FT —1o.9 SECONDS variables In:
111 1 ' TOTAL FOR MANEUVER ONCOMING VEHICLE TRAVELED pELSSngS COV
1.11800 FT -13 7 SECONDS — 834 FT — 13.7 SECONDS the methoccll
1"‘1 "1 field recor 5
11'11 distances an
1. ~ 1, mama—4mg;
'1 1111' 26 24 22 20 18 I6 14 12 lo a 6 1+ z o The dete-3r
1111 . 1 STATION maneuver 1s
1 1 11.11 ' FIGURE 9.—CRITICAL POSITIONS or VEHICLES AFTER COMPLETION or PASSING MANEUVER AND SPEEDS 0F VEHICLES THROUGH won, but t
11.1 1 ENTIRE STUDY SECTION. :‘i'él‘ffiiflgnag
1 1 . . . -
11111 1 1 long W1th01u’0 blttmg N0. .1 but he can reduce the space vehicle traveled 834 feet during the maneuver and'662 1101‘s. 0f SUE
1' 1 9111 between his car and vehicle N o. 1 so that No. 3 will feet while the passing vehicle was in the left lane. The passmg H1111?
1 1 be _requ1red to crowd his way back to the right lane. net result of the passing maneuver is that vehicles No. serve .the'r -
1 I1" ‘11 Neitfiier 5'lVO. 2 nor No. 3 can as yet see the oncoming %anddNo. 3hhave levers-Ed their respective positions. giggeclgrggfl
‘11. ‘1 1 car 9.. . rov1 ing t ere are su cient passing sections and
'1 11111- .11 Pos1tion 5 .(fig. 7) occurs 2.9 seconds after position 4, “holes” in oncoming traffic along the remaining portion 100" place _a
1 11' 1 11 and the passmg vehicle is now even with No. 2 and isi of this hi hwa vehicle No. 3 mi ht be able to ass two 0'95. tr aveln
.1 , 11 . . g y. . g p _
111.11 151‘ 11 no'longer accelerating: Vehicle N o. 2 has decelerated or three more of the cars of this group before getting to “1111111111111 511
1111.11}: 1‘1 9. httle and the oncoming vehicle No. 5 is now in view. the next town, thereby arriving a little sooner than if 111761.37 ' To
1 1111 1.1 L. From figure '8, representing the sixth position of the no attempt were made to pass. It may be possible passmgs Inf
1 1111.1 1 maneuver, it is seen that the driver of the passing for No. 3 to pass all the preceding vehicles in this group neuver Whll‘
‘ 11 11 vehicle has .dec1ded not to try to pass more than one at the next section of highway with a long sight dis- 10 be passe<
1, 1 vehicle and is now cuttmg back into the “hole” between tance, providing oncoming traflic does not interfere. In figure
111111 1 No. 1 and No. 2. This occurs 2.7 seconds after No. 2 Vehicle