This material is very helpful to understand LOS with definitions, classifications, factors affecting LOS, Calculation Method of LOS

2. Submitted By:
Student ID: 1405006, 1405012
Submitted To:
Md. Rabiul Islam
Assistant Professor, Department of Urban and Regional Planning
Md. Shah Jalal Mishuk
Lecturer, Department of Urban and Regional Planning
Course No. URP 342 Course Title: Traffic and Transportation Studio
Department of Urban and Regional Planning
Chittagong University of Engineering and Technology

3. LEVEL OF SERVICE
Level of service (LOS) is a qualitative measure used to relate the quality of traffic service.
LOS is used to analyze highways by categorizing traffic flow and assigning quality levels of
traffic based on performance measure like speed, density, delay etc.
Source: Kadiyali. 2010 Source: Highway Capacity Manual, 1994
Fig 1.2 V/C Ratio & LOS
VOLUME/CAPACITY RATIO
LOS A
LOS B
LOS F
LOS E
LOS D
LOS C
Fig 1.1 Level of Service A to F

4. CLASSIFICATION OF LEVEL OF SERVICE
The parameter which is used to measure LOS are:
a)Density b)Delay c)Speed
Most important classification of transportation facilities from the engineering
perspective is based on the continuity of flow, that is
a) uninterrupted flow and
b) interrupted flow
Classification is also possible basing on intersections. such as:
a) Signalized and
b) unsignalized

5. CLASSIFICATION OF LEVEL OF SERVICE…
LOS FOR A BASIC FREEWAY SEGMENT
LOS Vehicles per km
per lane
Velocity v/c
(veh/km/lane) (Km/hr)
A 0-7 120 0.35
B 7-11 120 0.55
C 11-16 114 0.77
D 16-22 99 0.92
E 22-28 85 1.0
F > 28 < 85 > 1.0
LOS FOR AN INTERSECTION
LOS Control Delay Delay
sec/veh
(signalised)
sec/veh (unsignalised)
A ≤ 10 ≤ 10
B 10-20 10-15
C 20-35 15-25
D 35-55 25-35
E 55-80 35-50
F > 80 > 50

6. CLASSIFICATION OF LEVEL OF SERVICE…

7. ❖LOS A:
▪ Traffic flows or above the posted speed
▪ complete mobility between lanes.
▪ average spacing between vehicles is about 550 ft(167 m)
or 27 car lengths.
▪ Motorists have a high-level of physical and psychological
comfort.
▪ generally occurs late at night in urban areas and
frequently in rural areas.
❖LOS B:
▪ reasonably free flow.
▪ traffic stream is slightly restricted than LOS A.
▪ The lowest average vehicle spacing is about 330 ft(100
m) or 16 car lengths.
▪ Motorists still have a high level of physical and
psychological comfort.
CLASSIFICATION OF LEVEL OF SERVICE…
LOS A
LOS B

8. ❖ LOS C:
▪ stable flow, at or near free flow.
▪ lane changes require more driver awareness.
▪ Minimum vehicle spacing is about 220 ft(67 m) or 11 car
lengths.
▪ Most experienced drivers are comfortable
▪ Posted speed is maintained.
▪ This is the target LOS for some urban and most rural
highways.
❖ LOS D:
▪ approaching unstable flow.
▪ Freedom to maneuver within the traffic stream is much more
limited
▪ driver comfort levels decrease. Vehicles are spaced about
160 ft(50m) or 8 car lengths.
▪ Minor incidents i.e. a busy shopping corridor in the middle
of a weekday, or a functional urban highway during
commuting hours.
▪ It is a common goal for urban streets during peak hours.
▪ attaining LOS C would require prohibitive cost and
societal impact in bypass roads and lane additions.
CLASSIFICATION OF LEVEL OF SERVICE…
LOS D
LOS C

9. ❖ LOS E:
▪ Unstable flow, operating at capacity.
▪ Flow becomes irregular and speed varies rapidly
▪ Speeds rarely reach the posted limit.
▪ Vehicle spacing is about 6 car lengths, but speeds are still
at or above 50 mi/h(80 km/h).
▪ Any incident will create serious delays.
▪ Drivers' level of comfort become poor.
▪ This is a common standard in larger urban areas, where
some roadway congestion is inevitable.
❖ LOS F:
▪ Forced or breakdown flow. Every vehicle moves in
lockstep with the vehicle in front of it.
▪ Travel time cannot be predicted.
▪ A road in a constant traffic jam is at this los, because los
is an average or typical service rather than a constant
state.
▪ For example, a highway might be at los d for the am peak
hour.
CLASSIFICATION OF LEVEL OF SERVICE…
LOS E
LOS F

10. Factors Affecting Capacity and Level of Service
1. Roadway Factors
i. Laneway Width
ii. Lateral Clearance
iii. Shoulders
iv. Surface Condition
v. Alignment
vi. Grades
2. Traffic Factors
3. Speed and Travel Time
4. Freedom to Travel with Desired Speed
5. Driving Comfort and Convenience
6. Operating Cost

11. Factors Affecting Capacity and Level of ServiceLOS in other Transportation Network Elements
Performance of other transportation network elements can also be communicated by LOS.
Among them are:
1. Two-lane roadways
2. Multilane roadways
3. Open freeway segments
4. Freeway entrances (merges), exits (diverges), and weaving lanes
5. Bicycle facilities (measure of effectiveness: events per hour;
6. Bicyclist or overtaking a bicyclist traveling in the same direction)
7. Pedestrian facilities (HCM measure of effectiveness: pedestrians per unit area)

12. LOS for Different Types of Transportation Networks
LOS Operating Speed
(in K.P.H)
P.C.U(passenger
Car Units)
A 100 700
B 95 1100
C 90 1550
D 75 1850
E 50-6-0 2000
F 50
Urban Streets:
LOS Travel Speed
(in K.P.H)
Volume/Capacit
y Ratio
A 80 0.60
B 40 0.70
C 30 0.80
D 25 0.90
E 25 .95
F 15 >1
Two-Lane Rural Highways:
LOS Operating Speed
(in K.P.H)
Service Volumes
Per hour
A 100 420
B 90 750
C 80 1200
D 60 1800
E 50 2800
F <50 2000
LOS Operating Speed
(In K.P.H)
Service Volumes
Per hour
A 100 650
B 90 1000
C 75 1300
D 60 1600
E 50 2000
F <50
Freeways in Rural Areas :
Multi-Lane Rural Highways:

13. Calculation Methods:
Capacity is analyzed for each lane group entering the intersection. The capacity for each
lane group is
Ci = Si (gi / C)
where
Ci = capacity for a lane group I,
Si = saturation flow rate for lane group I, gi/C = effective green time over cycle time ratio
Although the capacity for the intersection as a whole can not be defined, a composite v/c
ratio can be defined by summing the v/c ratio for the critical lane group.
This is the critical v/c ratio, designated as Xc. This can be calculated from the equation
Xc = S (v/s) ci [C/(C-L)]
Where, Xc = critical v/c ratio for the intersection
S (v/s)ci =summation of the flow ratios for all critical lane groups I where v =
demand volume and s = saturation flow for each critical lane group
C = cycle length (use maximum acceptable)
L = total lost time per cycle

14. References:
Kadiyali, L. (2010). Traffic Engineering And Transportation Planning . New Delhi:
Khanna Publishers.
Rao, T. V. (2007). Capacity and Level of Service. In Introduction to Transportation
Engineering.
A Policy on Geometric Design of Highway and Streets. Washington DC: AASTHO,
1994.
Highway Capacity Manual. Washington DC: Transportation Research Board, 2000.
Final congestion management program for 2005, Retrieved from
http://ccag.ca.gov/wp-content/uploads/2014/07/cmp_2005_Appendix_B.pdf