justifying rail bias factor for houston metro’s transit model
DESCRIPTION
Justifying Rail Bias Factor for Houston METRO’s Transit Model. Presentation by Vijay Mahal, HDR Inc Vincent Sanders, Houston METRO May 18, 2009 TRB Applications Conference Houston, Texas. Outline of Presentation. Houston’s Long range Transit Plan- MetroSolutions - PowerPoint PPT PresentationTRANSCRIPT
Justifying Rail Bias Factor for Houston METRO’s Transit Model
Presentation by
Vijay Mahal, HDR Inc
Vincent Sanders, Houston METRO
May 18, 2009
TRB Applications Conference
Houston, Texas
Outline of Presentation Houston’s Long range Transit Plan- MetroSolutions Houston’s first Light Rail Line- Phase I
Description Ridership profile
Houston METRO’s travel model – earlier version Need for Rail Bias factor Incorporation of Rail Bias Model application / Conclusions
Houston METRO’s Long Range Plan
Development of METROSolutions Voter referendum Different Phases The Redline (Phase 1)
Houston’s first LRT opens January 2004
Houston’s first Light Rail
Starter line is 7.5 miles long 16 stations Serves very important activity
centers (CBD, TMC, UH, HCC, Rice)
High frequency Uses German-made Siemens cars Top speeds achievable: 66 MPH
Stations a few blocks apart in CBD and about one mile apart outside of CBD
Uses Clean electric power Moves large volumes of people Operates faster than local buses
LRT Ridership Profile
Actual Ridership (Average Weekday Boardings, 2004 to 2007)
-
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
Jan-04 Mar Jun Sep Jan-05 Mar Jun Sep Jan-06 Mar Jun Sep Jan-07 Mar Jun Sep
Forecasts from Earlier Models
LRT ridership forecasts made during the 1990s Opening year (2004) forecast= 22,000 2020 forecast = 40,000 Actual ridership in September 2004 = 33,000 Actual current ridership = 44,000 The Red Line is considered the most successful line in the
country. Nov. 2007 Breaks 40 Million boardings
Sept. 2008 Breaks 50 Million boardings
So, what factors make this line so successful?
Travel Surveys
1st Survey in Sept 2004 (elaborate OD survey) 2nd Survey in November 2004 (Supplemental survey to
collect data on new riders) 3rd Survey in 2007 (OD survey to update model
parameters)
The 2004 O/D survey format
19 Question survey Basic demographics question were asked
age, gender, income, ethnicity, available vehicles Access-Egress patterns, type of trips, transfer, types of
fare media, how long & often have you used transit One question not asked: Were you a METRO
user before METRORail?
Supplemental Survey Instrument
Highlights from SurveySurvey conducted from November 8th 2004 to November 17th 2004
Total surveys handed out = 13,000Valid surveys returned = 5,940 (very high response)
Percent of new riders (Question 1 of survey) was 37 %
Were you a METRO bus/shuttle rider before METRORail opened?
Houstonians Offer Positive Comments
Survey response:• 90 % comments were positive• 3 % neutral, 7 % negative• 36 % wanted immediate system expansionMost cited reasons for positive response• reliability• comfort / smoothness of ride• faster than bus
Houston METRO’s original Mode Choice Model
Light Rail data was never a part of Houston METRO’s mode
choice model estimation Primary Data Sources
1985 Home Interview Survey 1990 Journey to Work Census data 1995 and 2001 On-board OD surveys Periodic ride check data
LRT came into existence in January 2004 None of the data set contained the rail attributes
Earlier Planning Studies
Major Planning Studies for this region began in the mid 1990s
For the Red line, Alternative Analysis & Environmental documents in progress Travel forecasts were needed urgently for a mode that didn’t exist Modifications made to the mode choice model to accommodate LRT
(quick fix)
Structure of the original Mode Choice Model
Structure of the revised Mode Choice model
Mode-Specific Constants
Utility equationsOriginal Model U LB = C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
U CB = K 1 + C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
Revised Model U LB = C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
U CB = K 1 + C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
U EX = K 2 + C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
U LRT = C1 x Inveh TT + C2 x Out-of-veh TT + C3 x Fare
Purpose of Mode Specific constant
Most models consider travel time, travel costs and some measurable service characteristics (# of Xfers)
Visibility, comfort of ride, reliability, passenger amenities etc. – are non-quantifiable and not considered
In theory, mode specific constant is supposed to represent the non-quantifiable factors
Misuse of Mode Specific constant : correction factors (for calibration purposes)
Underestimation of LRT forecasts
LRT forecasts were significantly underestimated when its mode bias constant was zero
Opening year (2004) forecasts = 22,000 daily boardings Horizon year (2020) forecasts = 40,000 daily boardings Current (2009) actual ridership = 44,000 daily boardings What was the most likely reason for the underestimation? Survey results clearly demonstrated Houstonians perceive LRT
as a Premium mode. So, a mode specific constant was introduced to represent the Rail Bias.
Incorporating Rail Bias Factor
Methodology Started with a rail bias factor of 0.33 used in the old
Minneapolis and San Diego models. In terms of IVTT, this equals 6.73 min in our models.
Run model with and without LRT network Analyze ridership and new trips and compare them to
survey results Increase bias factor if necessary and repeat the process Final factor was 0.50 (equal to 10.2 minutes of IVTT)
Calibration Results (Yr 2004)
Iteration Rail Bias factor
Value of Rail Bias in terms of in-vehicle
time
Estimated LRT
ridership
Increase in system
wide linked transit trips (new trips)
Portion of rail trips that are
new to the transit system
1 0 0 22,000 4,600 20 % 2 0.33 6.73 29,400 8,200 28 % 3 0.40 8.16 30,700 9,800 32 % 4 0.45 9.18 31,500 11,000 35 % 5 0.50 10.2 33,000 11,900 36 %
Model Application
Application results
Observed rail boardings in October 2008 (from APC System)
41,000
Estimated rail boardings from the model for 2008 (with Rail Bias
42,000
Projected rail boardings from the model for 2020 (with Rail Bias)
67,000
Projected rail boardings from the model for 2030 (with Rail Bias)
81,000
Rail Bias Impacts on New Starts projects
The North Corridor Extension
Rail Bias Impacts
Ridership projections increased by about 20 to 25 percent
User Benefits increased by about 15 percent Distribution of user benefits improved Most diagnostic statistics from SUMMIT reasonable
Conclusions
Travel surveys reveal Houstonians perceive LRT as a premium mode. Its ride quality, reliability, station amenities are as important to them as its travel times and frequency. They have a positive Bias towards rail.
The rail bias factor in Houston is worth approximately 10 min of IVTT in comparison to local bus mode
Rail Bias can improve User Benefits and ridership- in our case about 15 to 20 percent