Meeting_Body
AD HOC CUSTOMER EXPERIENCE COMMITTEE
MAY 17, 2018
Subject
SUBJECT: SEVERELY CONGESTED BUS CORRIDORS
Action
ACTION: RECEIVE AND FILE
Heading
RECOMMENDATION
Title
RECEIVE AND FILE status report identifying the most severely congested bus corridors within Metro’s service area.
Issue
ISSUE
As part of the NextGen Bus Study, staff has developed a tool that allows us to identify the impacts of traffic congestion on bus speeds. This report describes the methodology used in the tool, and identifies the 20 most severely impacted corridors.
Discussion
DISCUSSION
In recent years, there have been a number of studies identifying the most congested highway networks in the United States. Various cities are ranked on the basis of hours of delay experienced by commuters annually. The goal of these studies is to identify opportunities to improve traffic flow.
There are two key metrics used in these evaluations - 1) Threshold Speed defined as the uncongested speed achieved by vehicles on each highway segment, and 2) a Travel Time Index (TTI) which compares the actual travel time at any given time period to its Threshold Speed. For example, if it takes 4 minutes to travel one mile at the uncongested Threshold Speed, but 6 minutes during the congested peak period, then the Travel Time Index is 6 minutes divided by 4 minutes, or 1.5.
These metrics were originally developed at the Transportation Institute of Texas A&M University. The lowest possible value for the TTI is 1.0 which signifies travel at the uncongested speed. The Institute determined that values in excess of 1.25 constitutes severe congestion, and values in excess of 1.5 represents very severe or extreme congestion.
Staff determined that a similar metric is needed to analyze bus speeds along congested corridors in Los Angeles. The goal of this effort is to be able to determine when and where buses experience the most adverse impacts to speeds due to traffic, poor signal coordination, or other factors.
Metro maintains a database of time stamped, locational information on all buses as transmitted by the onboard computers on each bus. Weekday data from October 2017 was downloaded and processed by time of day to determine the uncongested speed of each bus line by segment as well as the average speed by segment for each daily time period (AM Peak, Midday, PM Peak, etc.).
Segments were defined from scheduled Time Point to Time Point. The bus onboard computer saves records a time stamp each time it passes a Time Point. A record is also produced when door open and close at stops. Running times by time period were then analyzed, and a Transit Traveltime Index was calculated for each segment and time of day. A tool was built to allow the user to query the database for each bus line, direction of travel, time of day, jurisdiction and neighborhood.
Using a Transit Travel time Index of 1.5 as an indicator of extreme congestion, bus corridors experiencing these conditions for an extended period of time were identified. There were 20 locations experiencing extreme congestion for 22 or more hours a day (both directions of travel combined).
Table 1 identifies these locations as well as the duration of severe congestion by direction of travel. These corridors are mapped on Attachment A. The two most extreme locations (Santa Monica Bl and Ventura Bl) experience severe adverse impacts on bus speeds continuously from 6am to 9pm daily. Not only do these conditions increase running time by 50% or more, they also adversely impact on-time performance and serve as an impediment to transit use.
Table 1 - Locations Experiencing Extreme Congestion Impacts on Bus Speeds
|
Corridor |
Daily Hours of Excessive Congestion |
Bus Line(s) Impacted |
|
|
Dir 1 |
Dir 2 |
|
|
|
|
|
|
|
Santa Monica Bl |
15 |
15 |
4, 704 |
|
Ventura Bl |
15 |
15 |
150, 750 |
|
Glendale Av / Brand Bl |
15 |
13 |
92 |
|
Venice Bl |
15 |
10 |
33. 733 |
|
Fairfax Av |
15 |
9 |
217, 780 |
|
Olympic Bl |
13 |
13 |
28, 728 |
|
Martin Luther King Bl, Crenshaw Bl, Hawthorne Av |
13 |
13 |
40, 740 |
|
Compton Av |
13 |
13 |
55 |
|
Long Beach Bl |
13 |
13 |
60, 760 |
|
Cesar Chavez Av |
13 |
13 |
68 |
|
La Cienega Bl |
13 |
13 |
105 |
|
Van Nuys Bl |
13 |
13 |
233 |
|
Soto St |
13 |
13 |
251, 751 |
|
Western Av |
13 |
12 |
207, 757 |
|
Wilshire Bl |
13 |
10 |
20, 720 |
|
Jefferson Bl |
13 |
10 |
35 |
|
Central Av |
13 |
10 |
53 |
|
Florence Av |
13 |
10 |
111 |
|
Vermont AV |
13 |
10 |
204, 754 |
|
Sunland Bl |
13 |
10 |
222 |
Next_Steps
NEXT STEPS
A follow up report for June 2018 will identify one line as a case study to identify congestion hotspots, root cause for the congestion, and a toolbox or improvements to address the congestion.
Attachments
ATTACHMENTS
Attachment A - Congested Bus Corridor Map
Prepared_by
Prepared by: Dana Woodbury, Manager Transportation Planning (213) 922-4207
Gary Spivack, Deputy Executive Officer (213) 418-3432
Conan Cheung, Senior Executive Officer (213) 418-3034
Reviewed_By
Reviewed by: James T. Gallagher, Chief Operations Officer (213) 418-3108
