Metro - File #: 2018-0305

• File #: 2018-0305
• Type: Informational Report
• Status: Agenda Ready
• File created: 5/14/2018
• In control: Ad Hoc Customer Experience Committee
• On agenda: 6/21/2018
• Title: RECEIVE AND FILE report identifying examples of actions available to mitigate the effects of severe bus congestion.
• Sponsors: Ad Hoc Customer Experience Committee
• Indexes: All Door Boarding, Bus rapid transit, Bus traffic, Curbs, Informational Report, Intersections, Median lanes, Merging traffic, Metro Rail A Line, Mitigation, Peak periods, Queuing, Traffic flow, Traffic signals, Traffic speed, Transit buses, Travel time

Meeting_Body

AD HOC CUSTOMER EXPERIENCE COMMITTEE

JUNE 21, 2018

Subject

SUBJECT:                     ACTIONS TO MITIGATE SEVERELY CONGESTED BUS

CORRIDORS

Action

ACTION:                     RECEIVE AND FILE

Heading

RECOMMENDATION

Title

RECEIVE AND FILE report identifying examples of actions available to mitigate the effects of severe bus congestion.

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 identifies the severity of congestion along a sample bus corridor (Vermont Av.) and identifies examples of mitigating actions to reduce the impact on bus speeds.

Discussion
DISCUSSION

Vermont Av. was chosen as an example corridor because it has been studied in detail for upgrade to Bus Rapid Transit (BRT) and possible future rail operation. The corridor is currently served by a Local bus (Line 204) and a Rapid bus (Line 754). Service is operated over a 12.5 mile segment from Vermont and 120^th St. on the southern end to Sunset Bl. at the northern end (Figure 1).

Rapid Line 754 has 24 stops, and Local service on Line 204 serves 68 stops. Rapid service averages about 11.5 mph during peak periods compared with 9.0 mph on Local service. The Rapid is 28% faster than the local requiring an average of 65 minutes to complete a peak period trip while the local takes an average of 84 minutes. The Rapid has about a 32% advantage during off peak periods averaging 56 minutes per trip instead of 73 minutes.

Much of the speed advantage of the Rapid bus can be attributed to serving 44 fewer stops per trip as well as some time savings as a result of signal priority. Only buses equipped with devices that broadcast their presence to the city’s traffic signals receive this priority treatment. Starting June 2018, All Door Boarding will be implemented on Line 754, reducing bus stop dwell times by allowing customers with valid TAP cards to board at any door.

Figure 1: Vermont Ave. Studied BRT Proposal

The Vermont Av. bus service is the most productive in the system with Line 754 averaging 80.1 boardings per revenue service hour on an average weekday (18,422 daily boardings), and Line 204 averaging 75.3 boardings per revenue service hour (20,843 daily boardings).

Vermont Av. buses are subjected to severe congestion over much of the service day. The severity of congestion is measured by a Travel Time Index (TTI) which reflects the ratio of travel time for a given time period with travel time during uncongested time periods. A ratio greater than 1.25 is indicative of significant congestion (the bus is taking 25% longer to make the trip than it would without congestion being present). A ratio exceeding 1.50 is indicative of severe congestion. Line 204 experiences severe congestion throughout the day with a TTI averaging 1.55 during the AM Peak period increasing to 1.67 by midday and 1.75 during the PM Peak. Rapid Line 754 experiences TTI’s averaging 1.43 to 1.54 during the same time periods. It is less affected by traffic than the Local bus line because it does not make as many stops that require buses to merge in and out of the congested traffic flow.

Congestion Mitigations

The 12.5 mile Vermont Av. corridor exhibits three different street profiles: 1) Starting from the southern end, the first 2.5 miles from 120^th St. to about 88^th St. provides 3 traffic lanes and a parking lane in each direction separated by a wide median which itself could contain 2 travel lanes; 2) The following 2.5 miles from 88^th St. to Gage Av. retains the 3 traffic lanes plus a parking lane in each direction, but the median narrows considerably such that it can no longer contain even one traffic lane; and 3) The northern 7.5 miles from Gage Av. to Sunset Bl. only allows for two traffic lanes and a parking lane in each direction with virtually no median. Thus, the street becomes narrower and more congested as it passes through areas of increasing density.

A study of ways to upgrade Vermont Av. to Bus Rapid Transit (BRT) has been underway for the past few years. A number of mitigations benefitting bus movement have been identified in that study. This report will provide examples of these and others along with their applicability.

A.                     Stop Location - Generally it is preferable to locate bus stops on the far side of intersections so that the traffic signal only affects bus movement once, upon arrival, and can create gaps in the traffic flow allowing the bus to merge back into traffic more easily. There are times when this is not possible such as when an abutting property owner objects, when two lines cannot share a single stop because there is not enough space, a desirable transfer location (such as a rail station) is located near side, or there isn’t enough linear space. On Vermont Av. 76% of Rapid Line 754 stops and 44% of Line 204 stops are located far side.

B.                     Dwell Time Reduction - On some high demand bus lines it is possible to achieve significant time savings by converting to all door boarding. All door boarding allows customers with valid TAP cards to board at any door, increasing the flow into and through the bus. This feature will be implemented on Rapid Line 754 starting June 2018.

C.                     Exclusive Lanes - Exclusive lanes (Figure 2) free buses from interaction with other traffic (except at intersections). They are most beneficial if they add to the street capacity rather than sacrificing lanes from an already congested street. This may be accomplished through street widening, or where a sufficiently wide median exists, by adding lanes within the median.

Figure 2: Example of Exclusive Median Bus Lanes

Providing passenger stops may prove difficult if there is little space remaining after adding lanes to the median. Where space permits side platforms, this is ideal because standard buses can be employed. If there is only space for a center platform, then buses must either cross over to the opposite lane to serve each station or they must be equipped with left side doors. The Harbor Transitway Green Line station is an example of a center platform station requiring buses to cross over to serve the station and then cross back to continue on the transitway. The BRT implemented on Euclid Av. in Cleveland employs center platforms served by buses with left side doors (the buses also have right side doors because some operation is in street rather than on the exclusive guideway).

D.                     Peak Period Lanes - Peak period lanes (Figure 3) restrict use to only buses at specified times of the day (though other vehicles may encroach at intersections in order to make right turns). They provide a tradeoff because when limited to buses, the capacity of the street for other vehicles is reduced. Peak period lanes are limited to times of greatest congestion, and often require added enforcement to keep them clear of other vehicles. An example of this mitigation is the exclusive bus lanes on Wilshire Bl. during peak periods.

Figure 3: Example of Peak Period Bus Lane

E.                     Transit Signal Priority - Signal priorities can take several forms depending on the physical characteristics of the location (Figure 4) Key to its functioning is bus detection.

Figure 4: Example Transit Signal Priority Elements

If buses are equipped with an emitter that can be decoded by the city’s signal system, then signals can be programmed to provide extended green indications, or advance green in the instance when the signal is red upon approach. Of course, adjusting the signal timing can have adverse consequences for cross streets, so signal priority works best in a corridor with few major cross streets. It is also of greater benefit if any bus stop associated with the intersection is located on the far side so that the bus’s behavior is not affected by the signal twice.

F.                     Queue Jumps - The queue jump is an alternative form of transit signal priority that provides a dedicated curb lane for buses and an advance green when buses are detected in the curb lane (Figure 5).

Figure 5: Example of Bus Queue Jump

The dedicated bus lane at intersections can be readily provided when a parking lane is available without reducing street capacity. Whether through the use of an emitter or other sensing technology, the presence of a bus tells the traffic signal to provide a few seconds of advance green for buses so that they may “jump” ahead of other traffic.

G.                     Curb Extensions - These are often used to shorten the length of a crosswalk while making the pedestrians more visible to vehicle drivers. They are also a treatment for extending a bus stop out to the bus (Figure 6).

Figure 6: Example Bus Stop Curb Extension

This allows the bus to serve the stop from a moving lane making it easy to merge back into the traffic flow because the bus never left the flow. It also creates more sidewalk space for the bus stop and any associated street furniture. Since the bus remains in a moving lane when serving a bus stop it adversely impacts the flow of other traffic, but then our interest here is the bus and not the other traffic.

H.                     Passenger Islands - There may be occasions when the design of an intersection prevents a bus from serving the curb, or an extended curb. A median bus lane is one instance. Another would be where channelization separates right turning vehicles from the through traffic flow (Figure 7).

Figure 7: Example Bus Passenger Island

In the top center of Figure 7 there is an example of a passenger island serving buses continuing on the street exiting the illustration to the lower left. Without this treatment there would be no place to provide a bus stop for this line’s passengers anywhere within the immediate vicinity of the intersection. An example exists within downtown Los Angeles at Pico Bl. Northbound Hill St. continues directly across Pico Bl. while a left diverging Olive St. originates at this intersection. Several Metro and Muni buses serve a passenger island for Olive St. passengers.

Financial_Impact
FINANCIAL IMPACT

There is no budgetary or financial impact from the presentation of the information in this report. Application of the mitigation techniques could result in potential capital investments, which would likely be mitigated by increased speed and reliability resulting in decreased operating cost.

Next_Steps
NEXT STEPS

Staff will identify the five most heavily congested bus corridors within the network, including specific congestion hot spots and root causes.  We will then develop potential solutions to each hot spot and present a speed and reliability action plan to the Board within 6 months.

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, Service Development (213) 418-3034

Reviewed_By

Reviewed by:                      James T. Gallagher, Chief Operations Officer (213) 418-3108