Review of Chapter 3 of Complete Street Chicago: Design Guideline by Chicago Department of Trnasportation CDOT

1. Complete Street Design Guideline:
“Chicago”
Sabrena Jahan Ohi
Student ID: 15RB903
M1 Student
Transportation and Urban Engineering Laboratory

2. Chicago is the third most populous city in the
United States and the most populous city in
the state of Illinois with nearly 10million
people
Chicago's streets were laid out in a street
grid that grew from the city's original town site
plat. A scattering of diagonal streets, many of
them originally Native American trails, also
cross the city.
Chicago's Western Avenue is the longest
continuous urban street in the world.
ChiCago

3. Complete Street ChiCago

4. modal hierarChy
•Vulnerable group
•Downtown,
Commercial/
entertainment area
has high volume of
pedestrian
•Even if not dominant
user, still need to
provide facilities
•Facilities must
comply with ADA
Pedestrian
•Provide access to
essential services,
jobs and reduce
automobile demand
•Size and
characteristics of bus
operation influence
street design
•Access and volume at
train stations affect
design
Transit
•Complete street
must accommodate
cyclists
•Vulnerable user
•Faster than
pedestrian but
slower and less
visible than
automobile
•Critical link in city’s
freight network
Bicycle
•Accommodated
with constraints of
lower speed and
prudent driving
•Commercial
vehicles are given
preference to
ensure economic
sustainability
Auto

5. deSign treeS
Cross
Sections
Label Code=Mode.
Building,Roadway
Modal
Hierarchy
Building
Typology
Roadway
Typology
ROW width
Target Speed
Volume = ADT
Design Trees

6. deSign treeS: roadway Form and FunCtion
 Truck/ Bus lane 11
feet
 Auto/bike Shared
lane 14 feet
 Combination of travel
and parking no less
than 18 feet (11’ +7’)
 Typical parking lane
width 7ft
 Curb extension =
width of parking lane
– 1~2 feet
 Neighborhood
streets lanes are not
usually marked
 Frontage lane is the
side travel lane of
multiway
thoroughfare
* All dimensions are in feet

7. Cross-seCtion elements

8. Cross-seCtion elements
1.Curbs:
Prevent water and cars to encroach on sidewalk
2.Bicycle Facilities:
Separate cyclist from both pedestrian and cars
Accommodate both faster cyclists and leisure
riders
3.Onstreet Parking:
Supports storefront retail, slows moving traffic,
and protects people from errant drivers and fast
moving traffic.
Space is valuable real estate that can be used.
Problematic for cycling due to the increase
chance of being “doored” or cars idling in the
travel lane waiting for a parking space to
become available.
Does not make a street more or less
complete so If used careful design is required
Interstitial Area
1.Frontage Zone:
The area between the walkway and building,
fence or yard.
The edge of the right of way.
For front lawn with no fence zone width is
zero
2.Walking Zone:
Area dedicated to walking.
Must be straight and continuous with ADA-
compliant and clear of all obstructions.
Pedestrian volume influence zone width
3.Sidewalk Furniture Zone:
Located between curb and walking zone
To make walking zone free from obstruction
Pedestrian Realm

9. Cross-seCtion elements
Median
1.Bus Lanes:
Exclusively used by Bus
Form varies from rush-
hour only lane to
physically separated lane
For existing street, either
convert auto lanes or
remove parking; do not
widen roadway
If shared with bicycle,
special measures must be
taken
2.Travel Lanes:
Used by automobile, bikes
and transit
Provide minimum
number of lanes
Vehicle Realm

10. interseCtions: layout
 Most pedestrian crashes in Chicago occur within 125 feet of an intersection
 Some complex
intersections
are a result of
poor street
connectivity
Connectivity
 Excessive
pavement need to
be minimized to
reduced crossing
distances and
increased ecological
functionality.
Possible
Curb Extension
Excessive pavement
 Compact ones have three or four
legs and right angles.
 Complex ones are with multiple legs,
traffic islands, skewed angles, and/or
turn lanes.
 Intersections should be as
compact as possible but if not
possible, separate traffic flows with
islands and traffic control devices.
 Reconfiguring is made by converting
an X-intersection into two T-
intersections or squaring off Y-
junctions.
 More compact intersections are
preferable to fewer, complex ones.
Compact vs Complex

11. interseCtions: layout

12. interseCtions: Corner Design
Turning speed
•15 mph or less for passenger
vehicles
•R = V2
/15(0.01 E + F)
R = centerline turning radius (effective)
V = speed in miles per hour (mph)
E = super-elevation; 0 in urban conditions.
F = side friction factor
Effective Radius and All Lanes
•To find the path of large vehicles
traversing the intersection, and the
turning speed of passenger vehicles
•The effective radius is typically not the
same as the corner radius
•CDOT minimizes intersection size
with smaller corner radii, set back
stop lines, and other techniques
•A large corner radius should not be
used to facilitate a truck turning from the
right lane into the right lane.
Design and control vehicle
•Select smaller design vehicle over
larger intersection
Right/Left turn on Red
•Can be prohibited
Turn Lanes
•Right turn lanes are to be avoided
as they widen the roadway and
facilitate higher turning speeds
Slip Lanes
•Provided after network analysis
and intersection minimizing with
Compliance committee approval
•Complimented with stop control
and a raised crosswalk
Highway Ramps
•Need to slow drivers down from
highway to street speeds before
they arrive to the intersection.

13.  A crosswalk is the extension of the sidewalk or walking area across the road.
 Pedestrians cross the street at a variety of locations
 Within the City of Chicago, pedestrians have the right-of-way at crosswalks unless
directed otherwise by traffic-control devices, police officers or traffic control aides.
IntersectIons: PedestrIan crossIngs
Facility Selection Methodology

14. The crossing treatment is largely a function of
automobile speed, automobile volume, roadway
configuration.
Multi-lane, high-speed, and high volume roads
require more aggressive treatments such as lane
narrowing, medians, overhead signs, and
advance stop lines.
Traffic control devices such as crosswalk
striping, yield signs, and signals may be
warranted
Treatment
Located where pedestrians want to cross, and where drivers can reasonably expect
pedestrians to cross.
People generally cross where it’s most convenient, in as direct a line to their destination as
possible. This is known as the desire line.
Locate according to the walking network, not the driving network.
Crossings should be provided where an analysis shows a concentration of origins and
destinations directly across from each other.
Site design and landscaping can orient people to preferred crossings,
Location
IntersectIons: PedestrIan crossIngs

15. IntersectIons: PedestrIan crossIngs
•After setting the location and type, the crossing can be
designed.
•People crossing at corners need protection from turning
drivers
•Crosswalk width ≥ sidewalk width
•Pedestrian ramps should be equal to the size of the
crosswalk
•Marked crosswalks should not be longer than three lanes.
•Unsignalized marked crosswalks shall be lit as brightly as
a signalized intersection
•A median or refuge island allows a person to cross one
direction of traffic at a time, making it much easier to find
and correctly identify acceptable gaps.
•The preferred width of a pedestrian refuge is eight to
10 feet with the minimum protected width is six feet
•Medians and refuge islands should include curbs,
bollards or other features to protect people waiting.
•The cut-through or ramp width should equal the width of
the crosswalk.
•Vertical elements such as trees, landscaping, and
overhead signage identify the island to drivers
Design and Operation

16. IntersectIons: drIveways
 Ramp the driveway up to meet
the sidewalk
 Carry the sidewalk grade and
surface material across the
driveway.
 Smallest dimension is to be
attained
 Design speed 10 mph.
 90 degrees orientation with the
street.
 Stop/yield signs for exiting traffic
with limited sight distance
 Minimum number to be designed
for reduced conflict
 Instead of driveway, utilizing an
alley is recommended by locating
the buildings along the street and
parking along the alley

17. geometrIc & oPeratIonal
PolIcIes: level of servIce
 Motor Vehicle Level of Service
(MVLOS) assesses delay for
motorists along a roadway
section or at a signalized
intersection (Scale: A to F)
 MVLOS does not consider
other modes or goals such as
safety and convenience.
 LOS should be consistent with
modal hierarchy.
 The maximum MVLOS for
CDOT-initiated projects shall
be E.
 LOS evaluations shall consider
cross flows as well as corridor
flows.
 Delay for pedestrians at
signals shall not exceed 60
seconds with minimum
sidewalk LOS B
 LOS evaluation with multi-hour
evaluations instead of peak-hour
only is encouraged
Pedestrian facilities
≫ Edge - building, setback, fence, open space
≫ Walkway - window shopping, vending, cross-flows
≫ Sidewalk furniture - cafe seating, trees, bicycle, bus stops
≫ Corner - queuing, accessibility
≫ Interference - driveways, alleys, parking, deliveries,
Transit facilities
≫ Headways
≫ Stops - amenities, spacing
≫ Interference - turns, deliveries, parking
≫ Bicycle facilities
≫ Separation, from pedestrian realm and roadway
≫ Guidance and prioritization, especially at conflict points
≫ Interference - turns, deliveries, parking
Automobile facilities
≫ Volume fluctuation - peak hour and off peak, weekday and
weekend, seasonal
≫ Loading and parking - coordinated with volume fluctuation
≫ Peak-hour operational issues - transportation demand
management, signal synchronization
≫ Interference - pedestrian crossings,
bicycle operations
Considerations

18. geometrIc & oPeratIonal
PolIcIes: traffIc control devIces
1. Synchronized signals are preferred and shall be set at or below the target speeds
2. Signal timing shall be adjusted during off peak hours to manage automobile speeds.
3. Fixed time signals are the preferred option.
4. Left turns should occur after the through movement (lagging).
5. All legs of all signalized intersections shall have marked crosswalks unless pedestrians are
prohibited from the roadway
6. “NO PEDESTRIANS” signs need to be accompanied by a physical barrier and positive
information about where pedestrians are to walk and/or cross the street.
7. Leading pedestrian intervals will be installed as per Chicago Pedestrian Plan.
8. Signals on transit-priority roadways should be timed to prioritize transit,
9. Signals on bicycle-priority roadways should be timed for bicycle commute speeds (15 mph),
Policy
 All traffic control devices shall support the complete streets modal
hierarchy.
 A well designed intersection can be made unusable by many if the
signal is optimized for automobile flow.
 Too many stop signs can make a roadway seem like a driving gauntlet.
 The lack of traffic control, especially at minor intersections, may make it
impossible for people who wish to cross the street.

19. Geometric & operational
policies: turns on red & lane Width
 While Right or Left Turns on Red (RTOR,
LTOR) are legal in the City of Chicago; they
are a privilege, not a right.
 Turns on Red (RTOR, LTOR) adversely
impact pedestrian comfort and safety.
 Pedestrian safety at transit stops is
compromised when drivers turn while
people are crossing the street after getting
off the bus.
 Right turns on red also restrict bicycle travel.
 If accommodating turns on red adversely
impacts the design, the turn will be
prohibited
Turns On Red
Converting 10 feet lanes into 12 feet
•On a six lane roadway has great impact as
this equals another lane, two bike lanes, a
wider sidewalk, on-street parking, or a
median.
•Increased crossing affecting signal timing.
Higher travel speeds
•No improvement in safety
Policy
•The standard lane width 10 feet
•One lane per direction on scheduled
Chicago Transit Authority (CTA) bus routes
and/or on a mapped truck route may be 11
feet wide.
≫ Thoroughfare: 10-11feet
≫ Connector: 9-11 feet
≫ Main Street: 9-10 feet
≫ Neighborhood Street: n/a
Lane Width

20. Geometric & operational
policies: desiGn & control vehicles
Design Vehicle
The design vehicle influences several geometric design features
including lane width, corner radii
Larger ones increase turning speed and crossing distances
Smaller ones result in frequent instances of trucks driving over curbs on
street corners, endangering pedestrians
It is best to err on the side of too small than too large for urban
setting.
Design vehicles for different roadway typology
≫Thoroughfare: WB-50
≫ Connector: BUS-4035
≫ Main Street: SU-3036
≫ Neighborhood Street: DL-23
≫ Service Way: DL-23
Delivery Van (DL-23)
Length 23 feet, Width 8.5 feet (10 feet with mirrors), Height 10 feet
with turning radii 29 feet outside, 23.3 feet centerline, and 22.5 feet inside
Control Vehicle
•The design vehicle keeps an intersection compact for everyday use, the
control vehicle allows access by necessary vehicles.
•A control vehicle utilizes all traversable parts of an intersection, including
driving over curbs and across centerlines for emergency access

21. Geometric & operational
policies: desiGn & tarGet speed
• Design speed is set as high as
practical, usually over the speed limit
• For complete streets, CDOT will use
target speeds instead of design
speed, where the design and operation
of a street is set to induce drivers to
drive at or below the speed limit.
≫ Thoroughfare: 25-30 mph
≫ Connector: 20-30 mph
≫ Main Street: 15-25 mph
≫ Neighborhood Street: 10-20 mph
≫ Service Way: 5-10 mph
Speed control elements are often necessary to
maintain target speeds
Signals synchronized to target speed
Narrower lanes, especially on Main Streets,
Neighborhood Streets and Service Ways
Roadway physically narrowed through bicycle
facilities, on-street parking, raised medians/islands,
curb extensions
Traffic calming devices like speed humps, mini-
roundabouts, chicanes
Limited sight distance such as buildings on the
corner
Terminating vistas, such as at a T-intersection or at
a traffic circle. When drivers cannot see to the horizon,
they tend to driver slower.
Rhythms created with trees, poles, landscaping, and
crosswalks

22. conclusion
 Complete street design requires:
i. Direction
ii. Observation
iii. Iteration
 Tenets of Street Design
1. Vehicle speed optimization
2. Exposure risk minimization
3. Behavior prediction of all mode user
 Although freight and goods delivery is an important part of
Chicago’s streets, It is not included as a specific mode
because it is cross modal- trucks (auto), bike trailer
(bicycle), and delivery person (pedestrian).
 Project-specific alternative hierarchies may be submitted
for Compliance Committee approval.
• Along a major transit corridor:
Transit > Pedestrian > Bicycle > Automobile
• Along a bicycle priority street:
Bicycle > Pedestrian > Transit > Automobile