Bus Rapid Transit Infrastructure Design Roadway and Junctions Bus stops Shreya Gadepalli Senior...
-
Upload
judith-gray -
Category
Documents
-
view
223 -
download
3
Transcript of Bus Rapid Transit Infrastructure Design Roadway and Junctions Bus stops Shreya Gadepalli Senior...
Bus Rapid TransitInfrastructure Design
Roadway and JunctionsBus stops
Shreya GadepalliSenior Program Director
Institute for transportation and Development Policy
Roadwayand
Junction Design
Intersections are criticalSO REDUCE CONFLICTS
Restrict turning options where possible (no right turns)
Avoid elements which can be put elsewhere (No parking near intersection +
Shift back BRT stations)
Provide time for pedestrians to cross and safe places to wait
General traffic capacity along a corridor
0
20
40
60
80
100
0 200 400 600 800 1000 1200meters
real
tivec
apci
ty %
Two phase signal
traffic direction
four phase signal
INTERSECTION CAPACITY varies with signal phasing
Signalized
Round about
(square geometry)
All turning movements possible in two signal
phases
Higher junction
capacity
Lower time lost for BRT as well as mixed
traffic
TWO PHASE OPTIONS
TWO PHASE OPTIONS
Signalized
Round about
(square geometry)
Size based on turning movement volume
Signal cycle an essential component of geometric
design
Short signal cycle essential avoid jam
Short signal cycle gives frequent pedestrian
crossing time
Signalized round about (Split
intersection)
Two Phase signal phase
Higher junction capacity
Multiple arms incorporated
TWO PHASE OPTIONS
Only straight movement allowed at
junction with two phase signals
Right turning movement through
U-turn - Left turn combination
TWO PHASE OPTIONS
BUS STATION LOCATION
Pedestrian behavior at junction
BUS STOP
BUS STOP
Bus blocks bus bay due during Red Phase not letting buses behind to access the bus stop
Risky behavior of Pedestrians to access the bus station
Pedestrian has to get across MV traffic of multiple directions in unsafe conditions
Fewer lanes for MV traffic at junction results in longer cycle time and lower junction capacity
Fewer lanes to cross to reach BRT station
Median Station allows for easy transfers
More space for mixed traffic at intersection
Synchronized signals for safe pedestrian crossing
BRT STOP AT INTERSECTIONBRT STOP AWAY FROM INTERSECTION
BUS STATION LOCATION
JUNCTION DESIGN
If BRT Station is at the Junction then
Many buses cannot utilize GREEN signal since earlier bus blocks the bus bay because it is waiting at the RED signal
Results in Long queues and bunching of buses and slows down the BRT system
May result in unwanted pedestrian behavior wishing to reach bus stop
BUS STATION LOCATION
Station setback from Intersection
Station at Intersection
BUS STATION LOCATION
BRT Stations
Speed vs saturation
B Rapid T B Slow T35
30
25
20
15
10
5
0
spe
ed
(km
/h)
saturation
0 0.1 0.2 0.50.40.3 0.80.70.6 10.9
cars
buses
BUS STATION SATURATION
BUS STATION CAPACITY
Increase in capacity with overtaking lane
Large bus flows with inadequate infrastructure causes huge bunching
Multiple bus bays with overtaking lane for entry exit as well as express services
reduces bus stop saturation and increases system capacity
Open bus platforms do not regulate where buses stop.This creates confusion at the station
Narrow overtaking lane obstructs oncoming buses and mixed traffic lanes – minimum width at bus station location with overtaking lane > 7m
LANES AT BUS STATIONS
Lane width requirement
Platform not properly aligned and only one door per bus at each station.
Undersized stations for actual demand
This caused crowing at inside stations
Bus queuing even at very low capacity (3000 pphpd)
Higher demand exists on the corridor so other buses ply in mixed traffic
BUS STATION CAPACITY
Station dwell time and capacity
BUS STATION SIZE
Waiting space inside bus station
One size does NOT fit all
Estimating passenger boarding and alighting demand of each bus stop location is important for bus station sizing.
Small and Narrow station
Creates large passenger queues outside the bus station
Results in discomfort and reduced efficiency of boarding
What it should be What it should NOT be
At level boarding
Maximum gap of 10cm between bus floor and Platform
BUS STATION PLATFORM
BUS STATION FEATURES
High ceiling with partial roof cover over Bus
Safe distance between Bus and
BRT station
(250mm)
System Identity and Station Name
Route information
Platform extension for close docking
of bus
(<125mm)
DOES SPEED MATTER?
• Most mass transit options can have relatively similar operating speed, other aspects remaining similar
• Speed is important since the fleet size required becomes lower for the same frequency of service
• Average speed increases as distance between stops increases. But speed of system matters only so far as total trip time of passengers is reduced
0
100
200
300
400
500
600
0 4 8 12 16 20 24 28 32 36 40 44 48 52
Time (sec)
Dis
tan
ce(m
) / S
pee
d (
kmp
h)
Speed curve
Distance traveled between stops
20
25
30
35
40
374 475 575 676 777 878 979 1079
Distance between stops (m)
Av
era
ge
Sp
ee
d (
km
ph
)
Stop spacing and Passenger trip time
0
5
10
15
20
25
30
35
40
Length (km)[Stop spacing
500m]
Time (min) [Stop spacing
500m]
Length (km)[Stop Spacing
1000m]
Time (min) [Stop Spacing
1000m]
Dis
tan
ce
(k
m)
/ Tim
e(m
in)
End of trip Walk
In vehicle time
Waiting time
Start of trip Walk
0
10
20
30
40
50
60
4 6 8 10 12 14 16
Total trip length (km)
To
tal t
rip
tim
e (m
in)
Stop spacing500m
Stop spacing1000m
• When trip lengths are short, closely placed stations are preferable since slow speed walk time becomes a large component of total trip time.
• As trip lengths increase, system speed can be increased by increasing station spacing
Bus Speed Profile vs Average Commercial Speed
0
20
40
60
80
0 6 12 18 24 30 36 42 48 54 82 88 94 100
106
112
118
124
130
Time (Sec)
Sp
eed
(km
ph
)
BRT and Pedestrian
PEDESTRIAN CROSSING every 120-200m
else they will make their own crossing!
Pedestrian Delay
Over 30 sec – Risky Behavior
Over 60 sec – would surely attempt to cross
Very long signal cycles with long waiting time for
pedestrians makes them take chances and meet with
accident.
Lower pedestrian delay requires shorter signal cycles
Zebra crossing Median treatment
Which one is better?The Answer is evident
At grade access to bus stops
HCBS Junction Conceptual Design
Waiting space for NMV in front of MV
Larger Pedestrian crossing space
No free left turns
-10
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Motor vehicle speed (km/h)
Perc
ent
Minor Injury
Major Injury
Death
Poly. (Major Injury )
Poly. (Death)
Poly. (Minor Injury)
Speed vs Injury
Removing free left turns will reduce
Left turn crashes by 19 %Collisions with pedestrians by 38%
Collisions with cyclists by 50%
Pedestrian Safety
Speed Drop Collision Drop
2 km/h 5%
5 km/h 15%
10 km/h 42%
5% Speed drop results in
15% fewer collisions10% fewer pedestrian fatalities 20% less severe pedestrian injuries
Left turning speed and turning radius
Target turning speed
Trucks < 10 km/hCars < 20 km/h
Effective Turning Radius
Use 4.5 m compound curve
NOT 15 m simple curve which results in 30-35 km/h
for cars)
High Vehicle speed but low visibility of Pedestrian
Unsafe
Left turn slip lane design
Lower Vehicle speed with better visibility of
Pedestrian
Safe
Slip lanesWhat they should NOT be
UNUSED but UNSAFE
Observing existing road use can teach
us a few things about safe and
realistic geometry
Fantasy
Make drivers and pedestrians behave
Develop a cleaner and quieter engine
Design city so everyone drives everywhere all the time
Build more capacity to move out of congestion
Something to think about
Reality
Eliminate or reduce severity of crashes
Minimize pollution and noise
Recapture urban space for people
Effectively utilize existing infrastructure
Vehicle speed Speed is a significant determinant of severity of crashes, should be logical
with respect to context, and is a critical factor in safety where there are conflicting traffic modes.
Lower vehicle speeds open a range of design options that enable a street to look less like an expressway and more like a neighborhood
street.
Pedestrian and bicycle exposure riskBy making the distance to cross the street shorter, the time spent
crossing the street is reduced and the exposure risk is subsequently reduced.
Driver predictabilityIf other street users can better predict how and where a particular
vehicle will be driven, the street will be safer.
3 Principals to remember