Summery of HCM 2010 Vol. 3 Chapter 17 (Pedestrian mode)

1. Urban Street Segments
(Pedestrian Mode)
Highway Capacity Manual (HCM) 2010
Vol. 3, Chp. 17
Sabrena Jahan Ohi

2. Outline

3. • An “X” is used to indicate an
association between a data
element and methodology
• A “Blank Cell” is not used as
input for the corresponding
methodology
Data
RequiRement

4. explanatiOn Of sOme teRm
 Total walkway width
• Distance from outside edge of road ( or face of curb) to far edge of the sidewalk
• Buffer width is included
• Paved shoulder is not included
• For varying width along segment use average value
 Effective width of fixed object
• Along the inside of the sidewalk
• Along the outside of the sidewalk
 Buffer width
• Distance between outside edge of road ( or face of curb) and the near edge of the sidewalk
• Not for pedestrian or vehicle use
• For vertical objects of 3ft or more high, spacing need to be recorded
 Pedestrian delay
• Delay to pedestrians who travel through the boundary intersection along the path parallel to segment
centerline
• Delay incurred by pedestrians who cross the subject segment at the nearest signal-controlled crossing
• Delay incurred when pedestrians wait at an uncontrolled crossing section (if illegal need not to count)
 Proportion of On-Street parking occupied
• Sum of the curb line length occupied by parked vehicle divided by the link length
• If parking is not allowed value is 0.0

5. Exhibit 17-39
pROblem DefinitiOn

6. StepS of methodology

7. Step 1
free flow Speed
 Average free flow speed (Spf) is the speed that reflect the condition in which there are negligible
pedestrian to pedestrian conflicts and negligible adjustments in a pedestrian’s desired walking path
to avoid other pedestrians
 Spf = 4.4 ft/s if elderly pedestrian proportion is with in 20%
 Spf = 3.3 ft/s if elderly pedestrian proportion is more than 20%
 An upgrade of 10% or more reduce speed by 0.3 ft/s
• Spf =Average free flow speed (ft/s)
 Spf = 4.4 ft/s

8. Step 2
AverAge pedeStriAn SpAce
• WE= Effective sidewalk width (ft)
• WT= Total sidewalk width (ft)
• Wbuf= Buffer width between roadway and sidewalk (ft)
• WO,i= Adjusted fixed-object effective width on inside of
sidewalk (ft)
• WO,o= Adjusted fixed-object effective width on outside of
sidewalk (ft)
• Ws,i= Shy distance on inside (curbside) of sidewalk (ft)
• Ws,o= Shy distance on outside of sidewalk (ft)
• wO,i= Effective width of fixed objects on inside of sidewalk
(ft)
• wO,o= Effective width of fixed objects on outside of
sidewalk (ft)
• pwindow= Proportion of sidewalk length adjacent to a
window display (decimal)
• pbuilding= Proportion of sidewalk length adjacent to a
building face (decimal)
• pfence= Proportion of sidewalk length adjacent to a fence
or low wall (decimal)
• vp= Pedestrian flow per unit width (p/ft/min)
• vped= Pedestrian flow rate in the subject sidewalk
(walking in both direction (p/h)
• Sp= Pedestrian walking speed (ft/s)
• S = Free-flow pedestrian walking speed (ft/s)

9. Step 3
ped. delAy At interSection
• dpp = delay incurred by pedestrian who travelled through the boundary intersection along a path
parallel to segment center line
• dpc = delay incurred by pedestrian who cross the segment at the nearest signal controlled crossing
• dpw = delay incurred by pedestrians waiting for a gap to cross the segment at an uncontrolled
location
 dpp = 40 s/p [From Chapter 18]
 dpc = 80 s/p [From Chapter 18]
 dpw = 740 s/p [From Chapter 19]

10. Step 4
ped. trAvel Speed
 Combination of time to walk the segment and delay at downstream boundary
intersection
 Travel speed is less than walking speed, Sp > STp,seg
 STp,seg ≥ 4.0 ft/s is desirable
 STp,seg ≤ 2.0 ft/s is undesirable
Where,
•STp,seg = Travel speed of through pedestrians for the segment (ft/s)
•L = Segment length (ft)
•Sp = Pedestrian walking speed (ft/s)
•dpp = Pedestrian delay when walking parallel to the segment (s/p)
• STp,seg < 4.0 ft/s, but considered acceptable but a higher value is desirable
(Sp from step 2; dpp from step 3; L is given)

11. Step 5
pedeStrian LOS ScOre fOr interSectiOn
• Ip,int = Pedestrian LOS score for the boundary intersection
 Ip,int = 0.0; for signalized boundary intersection with two-way STOP controlled
 For signalized boundary intersection Ip,int obtained from chapter 18
 Ip,int =3.60 [From Chapter 18]

12. Step 6
pedeStrian LOS ScOre fOr Link
Where,
•Ip,link= Pedestrian LOS score for link
•Fw= Cross section adjustment factor
•Fv= Motorized vehicle volume adjustment factor
•FS= Motorized vehicle speed adjustment factor
•ln(x) = natural log of x
•Wv= Effective total width of outside through lane, bicycle
lane, and shoulder as a function of traffic volume [Exhibit 17-
18]
•W1= Effective width of combined bicycle lane and shoulder
[Exhibit 17-18] (ft)
•ppk= proportion of on-street parking occupied (decimal)
•Wbuf= Buffer width between roadway and available sidewalk
(=0.0 if sidewalk does not exist (ft)
•fb= Buffer area coefficient= 5.37 for any continuous barrier at
least 3 ft high that is located between the sidewalk and the
outside edge of roadway; otherwise use 1.0
•WA= Available sidewalk width = 0.0 if sidewalk does not exist
or WT-Wbuf if sidewalk exists (ft)
•WaA= Adjusted available sidewalk width = min(WA, 10) (ft)
•fsw= Sidewalk width coefficient = 6.0-0.3 WaA
•vm= Midsegment demand flowrate (direction nearest to the
subject sidewalk) (veh/h)
•Nth= Number of through lanes on the segment in the subject
direction of travel (ln)
•SR= Motorized vehicle running speed = (3600L)/(5280tR)
(mi/h)
Exhibit 17-18
Condition
Variable when
condition is Satisfied
Variable when
condition is NOT
Satisfied
ppk= 0.0 Wt=Wol+Wbl+Wos
*
Wt=Wol+Wbl
vm>160veh/h or
street is divided
Wv=Wt Wv=Wt(2- 0.005 vm)
ppk < 0.25 or parking
is striped
W1=Wbl+WOS
*
W1= 10
• Wt= Total Width of the outside through lane, bicycle lane and paved shoulder
(ft)
• Wol= Width of outside through lane (ft)
• Wos
*
= Adjusted width of paved outside shoulder; if curb is present Wos
*
=Wos
-1.5 ≥ 0.0; otherwise Wos
*
=Wos (ft)
• Wos= Width of paved outside shoulder (ft)
• Wbl= Width of the bicycle lane = 0.0 if no bicycle lane is provided (ft)

13. Step 6
pedeStrian LOS ScOre fOr Link
 Wt= Wol+ Wbl = 12+5 =17 ft
• As ppk=0.2 (≠0.0)
 Wv= Wt= 17 ft
• As vm= 940 veh/h >160 veh/h
 WOS
*
= 9.5 ft
 WOS
*
= WOS-1.5 = 9.5-1.5 = 8.0 ft
• As street cross section is curved
 W1=Wbl+WOS
*
= 5+8 = 13 ft
• As ppk=0.2 (<0.25)
 WaA= min (WT – Wbuf , 10)
= min (10-5, 5) = 5.0 ft
 Repetitive vertical objects like trees are considered to be a continuous barrier in buffer if they are al
least 3 ft high with average spacing 20 ft or less
 Physical barrier and parked cars between moving vehicles and pedestrians increase the separation
space and the perception of service quality
 For discontinuous sidewalk in the study segment, each segment need to be evaluated individually
and then a weighted average would give LOS score or entire segment

14. Step 7
Link LOS
 Determined using pedestrian LOS, Ip,link (Step 6) and average pedestrian space, Ap (Step 2) with the
help of Table 17-3
 Absence of sidewalk results in pedestrians walking in the street and LOS is determined using Table 17-
4
 From Step 2, Ap = 32.0 ft2
/p
 From Step 6, Ip,link = 2.51
 Link LOS = C [From Table 17-3]
Table 17-3
Pedestrian
LOS Score
LOS by Average Pedestrian Space (ft2
/p)
>60
>40-
60
>24-40 >15-24
>8.0-
15a ≤8.0a
≤2.00 A B C D E F
>2.00-2.75 B B C D E F
>2.75-3.50 C C C D E F
>3.50-4.25 D D D D E F
>4.25-5.00 E E E E E F
>5.00 F F F F E F
a
In cross-flow situations, the LOS E/F threshold is 13 ft2
/p
Table 17-4
LOS LOS Score
A ≤2.00
B >2.00-2.75
C >2.75-3.50
D >3.50-4.25
E >4.25-5.00
F >5.00

15. Step 8
rOad crOSSing difficuLty factOr
 Crossing Option
i. Altered travel path by diverting to the nearest signalized crossing
ii. Continuation of original travel path with mid segment uncontrolled
crossing during acceptable gap in motorized vehicle
 Signalized crossing location
i. Signalized intersection
ii. Mid segment signalized crosswalk
 If crossing is somewhat uniform along the segment Dc is assumed
to be one-third of the distance between the nearest signal
controlled crossing
 If mid segment crossing is illegal ignore dpw and dpx= min (dpd,60)
 0.80 ≤ Fcd ≤ 1.20
Where,
•Dd= Diversion distance (ft)
•Dc= Distance to nearest signal-controlled crossing (ft)
•dpd= Pedestrian diversion delay (s/p)
•dpc= Pedestrian delay when crossing the segment at
the nearest signal-controlled crossing (s/p)
•dpx= Crossing delay = min (dpd,dpw,60) (s/p)
•dpw= Pedestrian waiting delay (s/p)
•Sp= Pedestrian walking speed (ft/s)
•Fcd= Roadway crossing difficulty factor
•Ip,link= Pedestrian LOS score for link
•Ip,int= Pedestrian LOS score for intersection

16. Step 8
Road CRoSSing diffiCulty faCtoR

17. Step 9
ped. loS SCoRe foR Segment
 Ip,seg = Fcd (0.318 Ip,link+ 0.220 Ip,int+ 1.606)
where.,
• Ip,seg = Pedestrian LOS score for the segment
• Fcd = Roadway crossing difficulty factor
• Ip,link= Pedestrian LOS score for the link
• Ip,int= Pedestrian LOS score for the boundary intersection
 Ip,seg = 1.20 (0.318 [2.51]+ 0.220 [3.60]+ 1.606) = 3.83

18. Step 10
Segment loS
 Determined using pedestrian LOS Score, Ip,seg (Step 9) and average pedestrian space, Ap (Step 2) with
the help of Table 17-3
 Absence of sidewalk results in pedestrians walking in the street and LOS is determined using Table 17-
4
 From Step 2, Ap = 32.0 ft2
/p
 From Step 9, Ip,seg = 3.83
 Link LOS = D [From Table 17-3]
Table 17-3
Pedestrian
LOS Score
LOS by Average Pedestrian Space (ft2
/p)
>60
>40-
60
>24-40 >15-24
>8.0-
15a ≤8.0a
≤2.00 A B C D E F
>2.00-2.75 B B C D E F
>2.75-3.50 C C C D E F
>3.50-4.25 D D D D E F
>4.25-5.00 E E E E E F
>5.00 F F F F E F
a
In cross-flow situations, the LOS E/F threshold is 13 ft2
/p
Table 17-4
LOS LOS Score
A ≤2.00
B >2.00-2.75
C >2.75-3.50
D >3.50-4.25
E >4.25-5.00
F >5.00