Freeway & Highway LOS (Transportation Engineering)
-
Upload
hossam-shafiq-i -
Category
Engineering
-
view
274 -
download
1
Transcript of Freeway & Highway LOS (Transportation Engineering)
![Page 1: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/1.jpg)
CE
E 3
20W
inte
r 20
06
Freeway & Highway Level of Service
CEE 320Steve Muench
![Page 2: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/2.jpg)
CE
E 3
20W
inte
r 20
06
Outline
1. Definitions
2. Level of Service (LOS)
3. Freeway Segment LOS Determinationa. Free-flow speed
b. Flow Rate
4. Multilane Highway LOS
5. Design Traffic Volume
![Page 3: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/3.jpg)
CE
E 3
20W
inte
r 20
06
I-5 Average Daily Traffic
from the WSDOT 2001 Annual Traffic Report
![Page 4: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/4.jpg)
CE
E 3
20W
inte
r 20
06
Freeway Defined
• A divided highway with full control of access and two or more lanes for the exclusive use of traffic in each direction.
• Assumptions– No interaction with adjacent facilities (streets,
other freeways)
– Free-flow conditions exist on either side of the facility being analyzed
– Outside the influence or ramps and weaving areas
![Page 5: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/5.jpg)
CE
E 3
20W
inte
r 20
06
Basic Freeway Segment
From Highway Capacity Manual, 2000
![Page 6: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/6.jpg)
CE
E 3
20W
inte
r 20
06
Definitions
• Freeway Capacity– The maximum sustained 15-min flow rate,
expressed in passenger cars per hour per lane, that can be accommodated by a uniform freeway segment under prevailing traffic and roadway conditions in one direction of flow.
![Page 7: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/7.jpg)
CE
E 3
20W
inte
r 20
06
Definitions – Flow Characteristics
• Undersaturated– Traffic flow that is unaffected by upstream or downstream
conditions.
• Queue discharge– Traffic flow that has just passed through a bottleneck and is
accelerating back to the FFS of the freeway.
• Oversaturated– Traffic flow that is influenced
by the effects of a downstream bottleneck.
From Highway Capacity Manual, 2000
![Page 8: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/8.jpg)
CE
E 3
20W
inte
r 20
06
Speed vs. Flow
Flow (veh/hr)
Spe
ed (
mph
)Sf
Free Flow Speed
Optimal flow, capacity, vm
Uncongested Flow
Congested Flow
Sm
![Page 9: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/9.jpg)
CE
E 3
20W
inte
r 20
06
Uncongested Flow
From Highway Capacity Manual, 2000
![Page 10: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/10.jpg)
CE
E 3
20W
inte
r 20
06
Definitions – Free-Flow Speed
• Free-Flow Speed (FFS)– The mean speed of passenger cars that can be
accommodated under low to moderate flow rates on a uniform freeway segment under prevailing roadway and traffic conditions.
• Factors affecting free-flow speed– Lane width– Lateral clearance– Number of lanes– Interchange density– Geometric design
![Page 11: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/11.jpg)
CE
E 3
20W
inte
r 20
06
Definitions
• Passenger car equivalents– Trucks and RVs behave differently– Baseline is a freeway with all passenger cars– Traffic is expressed in passenger cars per lane per hour
(pc/ln/hr or pcplph)
• Driver population– Non-commuters suck more at driving– They may affect capacity
• Capacity– Corresponds to LOS E and v/c = 1.0
![Page 12: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/12.jpg)
CE
E 3
20W
inte
r 20
06
Definitions – Level of Service (LOS)
• Chief measure of “quality of service”– Describes operational conditions within a traffic
stream.– Does not include safety
– Different measures for different facilities
• Six measures (A through F)• Freeway LOS
– Based on traffic density
![Page 13: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/13.jpg)
CE
E 3
20W
inte
r 20
06
Levels of Service
• LOS A– Free-flow operation
• LOS B– Reasonably free flow– Ability to maneuver is only
slightly restricted– Effects of minor incidents still
easily absorbed
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
![Page 14: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/14.jpg)
CE
E 3
20W
inte
r 20
06
Levels of Service
• LOS C– Speeds at or near FFS– Freedom to maneuver is
noticeably restricted– Queues may form behind any
significant blockage.
• LOS D– Speeds decline slightly with
increasing flows
– Density increases more quickly
– Freedom to maneuver is more noticeably limited
– Minor incidents create queuing
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
![Page 15: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/15.jpg)
CE
E 3
20W
inte
r 20
06
Levels of Service
• LOS E– Operation near or at capacity– No usable gaps in the traffic
stream– Operations extremely volatile– Any disruption causes queuing
• LOS F– Breakdown in flow– Queues form behind
breakdown points– Demand > capacity
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
![Page 16: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/16.jpg)
CE
E 3
20W
inte
r 20
06
Freeway LOS
![Page 17: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/17.jpg)
CE
E 3
20W
inte
r 20
06
LOS Calculation
• Does not consider– Special lanes reserved for a particular type of vehicle
(HOV, truck, climbing, etc.)– Extended bridge and tunnel segments– Segments near a toll plaza– Facilities with FFS < 55 mi/h or > 75 mi/h– Demand conditions in excess of capacity– Influence of downstream blockages or queuing– Posted speed limit– Extent of police enforcement– Intelligent transportation system features – Capacity-enhancing effects of ramp metering
Freeway LOS
![Page 18: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/18.jpg)
InputGeometric Data
Measured FFS or BFFSVolume
BFFS AdjustmentLane width
Number of lanesInterchange densityLateral clearance
Volume AdjustmentPHF
Number of lanesDriver populationHeavy vehicles
Compute FFS Compute flow rate
Define speed-flow curve
Determine speed using speed-flow curve
Compute density using flow rate and speed
Determine LOS
BFFS Input
Measured FFS Input
Freeway LOS
![Page 19: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/19.jpg)
CE
E 3
20W
inte
r 20
06
LOS
Crit
eri
a fo
r B
asi
c F
ree
wa
y S
egm
ent
s
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
Freeway LOS
![Page 20: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/20.jpg)
CE
E 3
20W
inte
r 20
06
Determining FFS
• Measure FFS in the field– Low to moderate traffic conditions
• Use a baseline and adjust it (BFFS)
IDNLCLW ffffBFFSFFS −−−−=FFS = free-flow speed (mph)
BFFS = base free-flow speed, 70 mph (urban), 75 mph (rural)
fLW = adjustment for lane width (mph)
fLC = adjustment for right-shoulder lateral clearance (mph)
fN = adjustment for number of lanes (mph)
fID = adjustment for interchange density (mph)
Freeway LOS
![Page 21: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/21.jpg)
CE
E 3
20W
inte
r 20
06
Lane Width Adjustment (fLW)
• Base condition (fLW = 0)– Average width of 12 ft. or wider across all lanes
From Highway Capacity Manual, 2000
Freeway LOS
![Page 22: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/22.jpg)
CE
E 3
20W
inte
r 20
06
Lateral Clearance Adjustment (fLC)
• Base condition (fLC = 0)– 6 ft. or greater on right side
– 2 ft. or greater on the median or left side
From Highway Capacity Manual, 2000
Freeway LOS
![Page 23: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/23.jpg)
CE
E 3
20W
inte
r 20
06
Number of Lanes Adjustment (fN)
• Base condition (fN = 0)– 5 or more lanes in one direction
– Do not include HOV lanes
– fN = 0 for all rural freeway segments
From Highway Capacity Manual, 2000
Freeway LOS
![Page 24: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/24.jpg)
CE
E 3
20W
inte
r 20
06
Interchange Density Adjustment (fIC)
• Base condition (fIC = 0)– 0.5 interchanges per mile (2-mile spacing)
– Interchange defined as having at least one on-ramp– Determined over 6-mile segment
From Highway Capacity Manual, 2000
Freeway LOS
![Page 25: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/25.jpg)
CE
E 3
20W
inte
r 20
06
Determining Flow Rate
• Adjust hourly volumes to get pc/ln/hr
pHVp ffNPHF
Vv
×××=
vp = 15-minute passenger-car equivalent flow rate (pcphpl)
V = hourly volume (veh/hr)
PHF = peak hour factor
N = number of lanes in one direction
fHV = heavy-vehicle adjustment factor
fP = driver population adjustment factor
Freeway LOS
![Page 26: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/26.jpg)
CE
E 3
20W
inte
r 20
06
Peak Hour Factor (PHF)
• Typical values– 0.80 to 0.95– Lower PHF characteristic or rural or off-peak
– Higher PHF typical of urban peak-hour
415 ×=V
VPHF
V = hourly volume (veh/hr) for hour of analysis
V15 = maxiumum 15-min. flow rate within hour of analysis
4 = Number of 15-min. periods per hour
Freeway LOS
![Page 27: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/27.jpg)
CE
E 3
20W
inte
r 20
06
Heavy Vehicle Adjustment (fHV)
• Base condition (fHV = 1.0)– No heavy vehicles
– Heavy vehicle = trucks, buses, RVs
• Two-step process– Determine passenger-car equivalents (ET)
– Determine fHV
Freeway LOS
![Page 28: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/28.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Extended segments method– Determine the type of terrain and select ET
– No one grade of 3% or more is longer than 0.25 miles OR
– No one grade of less than 3% is longer than 0.5 miles
From Highway Capacity Manual, 2000
Freeway LOS
![Page 29: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/29.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Specific grades method– Any grade of 3% or more that is longer than 0.25 miles
OR– Any grade of less than 3% that is longer than 0.5 miles
From Highway Capacity Manual, 2000
Freeway LOS
![Page 30: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/30.jpg)
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
Freeway LOS
![Page 31: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/31.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
Freeway LOS
![Page 32: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/32.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Composite grades method– Determines the effect of a series of steep
grades in succession
– Method OK if…• All subsection grades are less than 4%
OR• Total length of composite grade is less than 4000 ft.
– Otherwise, use a detailed technique in the Highway Capacity Manual (HCM)
From Highway Capacity Manual, 2000
Freeway LOS
![Page 33: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/33.jpg)
CE
E 3
20W
inte
r 20
06
Determine fHV
( ) ( )111
1
−+−+=
RRTTHV EPEPf
fHV = Heavy vehicle adjustment factor
ET, ER = Passenger-car equivalents for trucks/buses and RVs
PT, PR = Proportion of trucks/buses and RVs in traffic stream
Freeway LOS
![Page 34: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/34.jpg)
CE
E 3
20W
inte
r 20
06
Driver Population Adjustment (fP)
• Base condition (fP = 1.0)– Most drivers are familiar with the route
• Commuter drivers
– Typical values between 0.85 and 1.00
• Two-step process– Determine passenger-car equivalents (ET)
– Determine fHV
Freeway LOS
![Page 35: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/35.jpg)
CE
E 3
20W
inte
r 20
06
Define Speed-Flow Curve
Select a Speed-Flow curve based on FFS
From Highway Capacity Manual, 2000
Freeway LOS
![Page 36: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/36.jpg)
CE
E 3
20W
inte
r 20
06
Determine Average PC Speed (S)
Use vp and FFS curve to find average passenger car speed (S)
From Highway Capacity Manual, 2000
Freeway LOS
![Page 37: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/37.jpg)
CE
E 3
20W
inte
r 20
06
Determine Average PC Speed (S)
For 70 < FFS ≤ 75 mph AND (3400 – 30FFS) < vp ≤ 2400
For 55 < FFS ≤ 70 mph AND (3400 – 30FFS) < vp ≤ (1700 + 10FFS)
For 55 < FFS ≤ 75 mph AND vp < (3400 – 30FFS)
−
−+
−−=
6.2
100030
340030
3
160
FFS
FFSvFFSFFSS p
( )
−
−+−−=
6.2
170040
3400303407
9
1
FFS
FFSvFFSFFSS p
FFSS =
Freeway LOS
![Page 38: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/38.jpg)
CE
E 3
20W
inte
r 20
06
Determine Density
• Calculate density using:
S
vD p=
D = density (pc/mi/ln)
vp = flow rate (pc/hr/ln)
S = average passenger-car speed (mph)
Freeway LOS
![Page 39: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/39.jpg)
CE
E 3
20W
inte
r 20
06
LO
S C
rite
ria
for
Bas
ic F
reew
ay
Seg
men
ts
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
DetermineLOS
Freeway LOS
![Page 40: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/40.jpg)
CE
E 3
20W
inte
r 20
06
Example
Geometry• 11 ft. lane width• Left lateral clearance = 5 ft.• Right lateral clearance = 4 ft.
Other• 7 am PHF = 0.95• 10 pm PHF = 0.99• 2% trucks
• 3% buses
Determine the typical LOS for SR 520 eastbound near Microsoft (MP 10.25 – shown in the picture below) at 7 a.m. and 10 p.m.
from WSDOT’s SRWebhttp://srview.wsdot.wa.gov/
Freeway LOS
![Page 41: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/41.jpg)
CE
E 3
20W
inte
r 20
06
Determine FFS
Freeway LOS
![Page 42: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/42.jpg)
CE
E 3
20W
inte
r 20
06
Determine FFS
Freeway LOS
![Page 43: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/43.jpg)
CE
E 3
20W
inte
r 20
06
Determine FFS
In a 6-mile stretch from I-405 to Redmond there are 5 interchanges
from Microsoft MapPoint
Freeway LOS
![Page 44: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/44.jpg)
CE
E 3
20W
inte
r 20
06
Determine FFS
Freeway LOS
![Page 45: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/45.jpg)
CE
E 3
20W
inte
r 20
06
At 7am the ½ hour volume is about 4000 veh/hrAt 10 pm the ½ hour volume is about 1700 veh/hr
Graph from the Puget Sound Regional Council’s Puget Sound Trends, No. T6, July 1997
Determine Flow Rate (vp)
Freeway LOS
![Page 46: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/46.jpg)
CE
E 3
20W
inte
r 20
06
Determine Flow Rate (vp)
Freeway LOS
![Page 47: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/47.jpg)
CE
E 3
20W
inte
r 20
06
Determine LOS
Freeway LOS
![Page 48: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/48.jpg)
CE
E 3
20W
inte
r 20
06
LOS
Crit
eri
a fo
r B
asi
c F
ree
wa
y S
egm
ent
s
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
Freeway LOS
![Page 49: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/49.jpg)
CE
E 3
20W
inte
r 20
06
Multilane Highway LOS
![Page 50: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/50.jpg)
CE
E 3
20W
inte
r 20
06
Multilane Highway LOS
• Similar to Freeway LOS• A few minor differences
Multilane Highway LOS
![Page 51: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/51.jpg)
CE
E 3
20W
inte
r 20
06
Base Conditions for Multilane Highway
• Level terrain, with grades no greater than 2 percent• Minimum lane width = 12 ft • Objects no closer than 6 ft from the edge of the traveled
pavement (at the roadside or median)• No direct access points along the roadway• Divided highway• Traffic stream composed entirely of passenger cars• Free flow speed of 60 mph or more• Driver population composed principally of regular users
Multilane Highway LOS
![Page 52: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/52.jpg)
CE
E 3
20W
inte
r 20
06
Free Flow Speed (FFS)
• Measure FFS in the field– Low to moderate traffic conditions
• Use a baseline and adjust it (BFFS)
AMLCLW ffffBFFSFFS −−−−=FFS = free-flow speed (mph)
BFFS = base free-flow speed, 60 mph is typically used
fLW = adjustment for lane width (mph)
fLC = adjustment for right-shoulder lateral clearance (mph)
fM = adjustment for median type (mph)
fA = adjustment for access points (mph)
Multilane Highway LOS
![Page 53: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/53.jpg)
CE
E 3
20W
inte
r 20
06
Lane Width Adjustment (fLW)
• Base condition (fLW = 0)– Average width of 12 ft. or wider across all lanes
From Highway Capacity Manual, 2000
Multilane Highway LOS
Same as Freeway LOS
![Page 54: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/54.jpg)
CE
E 3
20W
inte
r 20
06
Lateral Clearance Adjustment (fLC)
• Base condition (fLC = 0)
– 12 ft or greater TLC
• LCL = 6 ft for undivided highways
– (accounted for in median type adjustment)
• LCL = 6 ft for two-way left-turn lanes
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
Multilane Highway LOS
LR LCLCTLC +=
![Page 55: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/55.jpg)
CE
E 3
20W
inte
r 20
06
Median Adjustment (fM)
• Base condition (fM = 0)– Divided highway
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 56: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/56.jpg)
CE
E 3
20W
inte
r 20
06
Access-Point Density Adjustment (fA)
• For each access point/mi FFS decreases by 0.25 mph
• Base condition (fA = 0)– 0 access points per mile
• For NAPM ≤ 40: fA = 0.25 × NAPM
• For NAPM > 40: fA = 10
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 57: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/57.jpg)
CE
E 3
20W
inte
r 20
06
Determining Flow Rate
• Adjust hourly volumes to get pc/ln/hr
pHVp ffNPHF
Vv
×××=
vp = 15-minute passenger-car equivalent flow rate (pcphpl)
V = hourly volume (veh/hr)
PHF = peak hour factor
N = number of lanes in one direction
fHV = heavy-vehicle adjustment factor
fP = driver population adjustment factor
Multilane Highway LOS
Same as Freeway LOS
![Page 58: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/58.jpg)
CE
E 3
20W
inte
r 20
06
Heavy Vehicle Adjustment (fHV)
• Base condition (fHV = 1.0)– No heavy vehicles
– Heavy vehicle = trucks, buses, RVs
• Two-step process– Determine passenger-car equivalents (ET)
– Determine fHV
Same as Freeway LOS
Multilane Highway LOS
![Page 59: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/59.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Extended segments method– Determine the type of terrain and select ET
– No one grade of 3% or more is longer than 0.5 miles OR
– No one grade of less than 3% is longer than 1 mile
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 60: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/60.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Specific grades method– Any grade of 3% or more that is longer than 0.5 miles
OR– Any grade of less than 3% that is longer than 1 mile
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 61: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/61.jpg)
CE
E 3
20W
inte
r 20
06
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
Same as Freeway LOS
Multilane Highway LOS
![Page 62: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/62.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
Same as Freeway LOS
Multilane Highway LOS
![Page 63: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/63.jpg)
CE
E 3
20W
inte
r 20
06
Passenger-Car Equivalents (ET)
• Composite grades method– Determines the effect of a series of steep
grades in succession
– Method OK if…• All subsection grades are less than 4%
OR• Total length of composite grade is less than 4000 ft.
– Otherwise, use a detailed technique in the Highway Capacity Manual (HCM)
From Highway Capacity Manual, 2000
Same as Freeway LOS
Multilane Highway LOS
![Page 64: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/64.jpg)
CE
E 3
20W
inte
r 20
06
Determine fHV
( ) ( )111
1
−+−+=
RRTTHV EPEPf
fHV = Heavy vehicle adjustment factor
ET, ER = Passenger-car equivalents for trucks/buses and RVs
PT, PR = Proportion of trucks/buses and RVs in traffic stream
Multilane Highway LOS
Same as Freeway LOS
![Page 65: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/65.jpg)
CE
E 3
20W
inte
r 20
06
Driver Population Adjustment (fP)
• Base condition (fP = 1.0)– Most drivers are familiar with the route
• Commuter drivers
– Typical values between 0.85 and 1.00
Same as Freeway LOS
Multilane Highway LOS
![Page 66: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/66.jpg)
CE
E 3
20W
inte
r 20
06
Determine Average PC Speed (S)
Use vp and FFS curve to find average passenger car speed (S)
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 67: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/67.jpg)
CE
E 3
20W
inte
r 20
06
Determine Average PC Speed (S)For 55 < FFS ≤ 60 mph AND vp > 1400
For 50 < FFS ≤ 55 mph AND vp > 1400
For 55 < FFS ≤ 75 mph AND vp < (3400 – 30FFS)
For vp < 1400
−
−
−−=
31.1
88028
140013
10
3
FFS
vFFSFFSS p
−
−
−−=
31.1
11815
171
1400
41
219
205
34
FFS
vFFSFFSS p
FFSS =
−
−
−−=
31.1
112036
1400
9
56
5
1
FFS
vFFSFFSS p
Multilane Highway LOS
![Page 68: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/68.jpg)
CE
E 3
20W
inte
r 20
06
Determine LOS
Use vp and passenger car speed (S)
From Highway Capacity Manual, 2000
Multilane Highway LOS
![Page 69: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/69.jpg)
CE
E 3
20W
inte
r 20
06
Determine Density
• Calculate density using:
S
vD p=
D = density (pc/mi/ln)
vp = flow rate (pc/hr/ln)
S = average passenger-car speed (mph)
Multilane Highway LOS
![Page 70: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/70.jpg)
CE
E 3
20W
inte
r 20
06
Fro
m H
ighw
ay C
apac
ity M
anua
l, 20
00
LOS Criteria for Multilane Highways
Multilane Highway LOS
![Page 71: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/71.jpg)
CE
E 3
20W
inte
r 20
06
Design Traffic Volumes
![Page 72: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/72.jpg)
CE
E 3
20W
inte
r 20
06
Design Traffic Volumes
• Need to select the appropriate hourly traffic volume to get the design LOS
![Page 73: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/73.jpg)
CE
E 3
20W
inte
r 20
06
Definitions
• Annual average daily traffic (AADT)– Annual traffic averaged on a daily basis
• Design hourly volume (DHV)– Traffic volume used for design calculations– Typically between the 10th and 50th highest volume hour
of the year (30th highest is most common)
• K-factor– Relationship between AADT and DHV
AADT
DHVK =
![Page 74: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/74.jpg)
CE
E 3
20W
inte
r 20
06
Definitions
• Directional distribution factor (D)– Factor reflecting the proportion of peak-hour traffic
traveling in the peak direction– Often there is much more traffic in one direction than
the other
• Directional design-hour volume (DDHV)
AADTDKDDHV ××=
![Page 75: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/75.jpg)
CE
E 3
20W
inte
r 20
06
Typical Graph
Hou
rly v
olum
e as
a p
ropo
rtio
n of
AA
DT
Number of hours (annually) withspecified or greater volumes
20 40 10060 8000.10
0.15
0.14
0.13
0.12
0.11
Highest 100 Hourly Volumes Over a One-Year Period for a Typical Roadway
![Page 76: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/76.jpg)
WSDOT Graphs
![Page 77: Freeway & Highway LOS (Transportation Engineering)](https://reader031.fdocuments.in/reader031/viewer/2022030318/5a6560997f8b9a931a8b4b21/html5/thumbnails/77.jpg)
CE
E 3
20W
inte
r 20
06
Primary References
• Mannering, F.L.; Kilareski, W.P. and Washburn, S.S. (2005). Principles of Highway Engineering and Traffic Analysis, Third Edition. Chapter 6
• Transportation Research Board. (2000). Highway Capacity Manual 2000. National Research Council, Washington, D.C.