TTENG 422 Traffic Operations Module 4 S2024.pdf

Traffic Calming tools and fundamental concepts

2. Traffic Calming:

What are Traffic Calming measures?

Traffic calming measures are physical road design elements and
non-physical measures intended to reduce vehicle speeds and
improve driver attentiveness.

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3. | Traffic Calming Concepts:

Objective:

To improve safety and the quality-of-life for residents by reducing

the impacts from speeding vehicles, cut-thru traffic, and careless
| drivers.

That will results in:

e Reduced speeding
e Reduced numbers and/or reduced severity of reported collisions

e Reduced cut-through traffic where existing levels are significant
and where the remedy will not create a problem on other streets

e A better environment for residents and business owners as
indicated by their sense of safety, property values, comfort in
usingthe-street; and: reduced traffic-related complaints

4. Traffic Calming Measures: Toolbox

+ Non-physical measures - include reducing obstructions that limit
driver visibility, signage, and striping improvements

e Narrowing measures - include bulbouts, chokers, and center
island narrowing

+ Horizontal measures - include traffic circles, roundabouts, and
chicanes

e Vertical measures - include speed humps and speed lumps
e Diversion Devices - includes partial and full street closures

Ref. “City of Stockton, CA, Traffic Calming Guidelines", 2008

5. | Traffic Calming Measures: Problem Types

Selecting Measures for the Problem Type

| are:

The major types of problems that result in a desire for traffic calming

Speeding - motor vehicle speeds are too high

Traffic Volumes - motor vehicle usage levels (all trips or non-local
trips only) are too high

Vehicle Safety - motor vehicles have an inordinate level of risk

Pedestrian Safety - motor vehicles cause an unnecessary risk to
pedestrians

Noise/Vibration/Air Pollution - motor vehicles cause excessive
levels'ofthese environmental effects

6. Traffic Calming Measures Selection & Problem Types

ypes of Measures

Type of Problem

Speeding

Vehicle
Tratfic Volume | Ceidents|

Pedestrian]
Satety

Nolse

lon-Physical Measures

fargeted Speed Enforcement

Radar Trailer

peed Feedback Signs

[Edgeline/Centerine Striping

[Optical Speed Bars

peed Limit Signage

peed Legends

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ruck Restriction Signs

[Cross Traffic Does Not Stop" Signage

Botts Dots/Raised Reflectors

IHigh- Visibility Crosswalks

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ngled Parking

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Measures

Bulbouts

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Îwo-Lane Chokers

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‘enter Island Narrowing/ Pedestrion
refuges

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jorlzontal Measures

raffic Circles

Roundabouts (Singie-Lane)

Lateral Shifts

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7. Traffic Calming Measures Selection &

Problem Types

ypes of Measures

Type of Problem

Speeding

Vehicle
Trafic Volume | cidents

Pedestrian
_Satety_

Noise

/ertical Measures

speed Humps:

speed Lumps

Speed Cushion

pit Speed Hump

Speed Tables

Raised Crosswalks

Raised Intersections

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xIx[xIx[x|x[x|x

fextured Pavement

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Diversion Devices

Full Closures

IHalf Closures

[Diagonal Diverters

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\edion Barriers

forced Tum Islands

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Key: @ = Strongly Appropriate

= = Moderately Appropriate

x = Inappropriate/Counterproductive

O = Indifferent

Ref. “City of Stockton, CA, Traffic Calming Guidelines", 2008

8. raffic Calming Measures Selection & Loca

ion Type

Residential Non-Residential
veas el Mesures Midblock | Intersection | Peundary ot | Midblock | intersection
\Non-Physical Measures
forgeted Speed Enforcement . = a rs A
Radar Trailer
peed Feedback Signs
Edgeine/Centerine Striping O x x D x
[Optical Speed Bars e x x a x
eed Limit Signage
O . . . .
speed Legends .
ruck Restriction Signs E x = x O
[Cross Traffic Does Not Stop" E 6 = e =
ignage
Bons Dols/Rased Reflectors — [On Cumes| ——X x . x
rn Unsignallzed | Unsignalized lünsignalized
enn ® | intersections | intersections © intersections
ngled Parking e x x a x
jarrewing Measures
Bulbouts x e e x O
iwo-Lane Chokers e x x e x
‘enter Island Namowing/
Pedestrian Refuges bd . °

9. Traffic Calming Measures Selection &
Location Type

Residential ‘Non-Residential
ess of Meca: Midblock| Intersection | Boundary of | Midbiock | intersection
Horizontal Measures
raffic Circles x . o x o
| Roundabouts (Single-Lane) x o © x O
| lateral Shifts
| IChicones ia * © *
fertical Measures IF
eed Cushions . * * * *
Speed Humps
/ speed Tables a E x ° En |
taised Crosswalks e o Q o x
{ised intersections x e e E e
jextured Pavement e e O ° e
Diversion Devices
Full Closures x e O x x
[Half Closures x e a x x
[Diagonal Diverters = O E El =
[Median Bariers E o e E E
Forced Tum Islands * o e x .
Key: [x = Seldom or never applicable. [e = Generally applicable.
O = Not applicable except in some cose:

10. Traffic Calming Measures & Traffic Constraints

Roadway Classification Bus or
Non- Emergency Other
ves of Menus Fert Residential esdential | Response | Considerations
jects | Collectors FONCTION | Route
[Non-Physical Measures! it
fargeted Speed Enforcement
Radar Trailers
peed Feedback Signs
y teriine St
Edgelne/Centerine Striping rs ox .
Speed Limit < 35 mph (None)
High Visibility Crosswalk
ADT < 4,000;
Angled Parking Width 48 feet: no Noluredwith bi
Speed Limit < 30 mph
(Narrowing Measures!
‘ADT < 20,000;
pobouts Speed Limit < 35 mph Ok | onbxe routes,
E ADT < 20,000; design with clear
Iwo-Lane Chokers Seed links oe inch ok das
‘enter island Narrowings/ ‘ADT < 20,000; Ox [pccommodaions
Pedestrian Refuges Speed Limit = 35 mph

11. Traffic Calming Measures & Traffic Constraints

Roadway Classification Bus or
Non- Emergenc: Other
pross st Maures Shoot, [Residential Rehsennel | Response | Considerations
Collectors Route
Horizontal Measures!
| Daily Entering | May be requied al
poste iles Rood Unis 3 regent colactorsreets|_ OK | rode 10%
mph | intersect with local streets
Must design] 900 $ 6% On
oundabouts Dai Entering Volume inscribed | yogan win clear
[Single-Lane) < 20.000; Speed Limit = 45 mph radius to be! A
100* feet | accommodations
calera! Shifis ‘ADT < 10,000; Speed Limit s 35 mph = Grade s 10%
IEnicanes ‘ADT < 5,000; Speed Limit < 35 mph Grade <8%
Vertical Measures!
peed Humps NO
Speed Lumps ADT <4,000; ‘OK
Speed Cushions oun OK user,
pli Speed Humps ‘OK
Speed Tables ‘OK
aised Crosswalks ADT $2,500; ‘OK
aised Intersections me ‘OK
fextured Pavement Yes OK None

| Traffic calming devices are suitable for existing and new streets.

12. Traffic Calming Measures & Traffi

Roadway Classification

c Constraints

Bus

Other

Peso Mscsures Collectors Route | Considerations
Streets
Diversion Devices?
Full Closures No No
ADT < 5,000; Public Works
Half Closures > 25% Non-Local & SURTD?
No :
Traffic must review (None)
[Diagonal Diverters
edian Barriers ‘ADT < 5,000; No
Forced Tum Islands > 25% Non-Local Traffic

'ombined Measures

Subject to Constraints of Component Measures

Not to be used on new streets.
San Joaquin Regional Transit District.

Ref.

“City of Stockton, CA, Traffic Calming Guidelines", 2008

13. Traffic Calming Concepts: Narrowing (Bulbouts)

14. Traffic Calming Concepts: Narrowing (Two Lane
Chokers)

15. Traffic Calming Concepts : Narrowing Measures

16. Traffic Calming Concepts: Narrowing Measures
(Pedestrian Refuge Islands)
After

17. Traffic Calming Concepts: Horizontal
Measures

18. Traffic Calming Concepts: Horizontal Measures
Traffic Circle

19. Traffic Calming Concepts: Horizontal Measures
Lateral Shifts

20. Traffic Calming Concepts: Horizontal Measures
Chicanes

21. Traffic Calming Concepts: Horizontal
Measures

22. Traffic Calming Concepts: Non Physical
Measures

SPEED |
LIMIT

23. Traffic Calming Concepts: : Non Physical
Measures

24. Traffic Calming Concepis: : Non Physical
Measures

25. Traffic Calming Concepts: Vertical Measures
Speed Bump

26. Traffic Calming Concepts: Vertical Measures
Speed Hump

27. Traffic Calming Concepts: Vertical Measures
Speed Table

28. Traffic Calming Concepts: Divergence Measures
Full Road Closure

29. Traffic Calming Concepts: Divergence
Measures
Partial Road Closure
| ; 3 a |
“at ie

30. | Traffic Calming Concepts: Divergence Measures
Diagonal Road Closure

Raised Island
with Verticle Curb

Bicycle
opening

Source: Traffic Calming State of the Practice, ITE, 1999

31. Traffic Calming Concepis: Divergence Measures
Median Barrier

32. Traffic Calming Concepts: Divergence
Measures
Forced Turn Exit

33. | Case Studies:
| Speed Hump Assessment
m

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34. | Impact of Speed Hump on Capacity & LOS

Speed humps are common traffic calming technique that is
being used in several cities allover the world.

| The main objective of speed humps is to reduce the speed of

| the traffic.
However, it has serious impact over the overall capacity of the
SAR ora Ci

Without

Speed Hump

Capacity
At Speed Hump

Flow Rate Q (velvianesr)

with speed hunp

Density
D (velvlane/km)

After Speed Hump

Jan
Density

Critical
Density

35. Impact of Soeed Hump on Capacity & LOS

Speed humps are common traffic calming technique that is be
used in several cities allover the world.

| The main objective of speed humps is to reduce the speed of
| traffic.

However, it has serious impact over the overall capacity of

/ Een 242. SEE-FOW CURES vi LOS CER
VA approach. m

Example:

36. Impact of Soeed Hump on Capacity & LOS
Operational Case: Existing Facility

Example:
Study the Effect of adding a speed hump on LOS and
the Overall capacity of the following approach.
Input:
Sumber of Lanes = 3
“ Lane Width= 3.4m
Median = Yes
Shoulders = 0.6 m
Traffic Volume = 1275
Topography (i.e. Terrain: Level /Rolling/ Mountainous)
HV% = 12% PHF = 0.9 , Access points = 6 acc. Pt. /km
Observed Speed = 70 km/hr ,

37. End of Module 4: