Flower Street Memo

8/14/2019 Flower Street Memo

1/4

~ Mid City/Exposition Light Rail Transit ProjectPreliminary Engineering ServicesContract No. EOO16

June 4, 2003

Mr. Steve BryeProject ManagerLos Angeles CountyMetropolitan TransportationAuthorityOne Gateway PlazaLos Angeles, CA 90012-2952

Dl\AJMllHARRISBooz Allen Hamilton Inc.Corrpro Companies, Ine.Diaz Yourman & AssodatesEgis-Semafy Inc.Gateway Science & EngineeringHarris Mil ler Mil ler & Hanson Inc.Jackie Patterson &AssociatesKAKU Assodates, Inc.Kal Krishnan Consult ing Services, Inc.Melendrez Design PartnersMyra L Frank & Associates, fne.PsomasThe Robert GroupZimmer Gunsul Frasca Partnership

Project 046105843.0002LOT No. 0117

Subject:

Dear Mr. Brye:

Exposition Light Rail Transit Project - Contract No. E0016Exposition Line Operation Simulation Results

The computer simulations of the Locally Preferred Alternative (LPA) and other shared use Blue Line and ExpoLine operations have been completed. As described in the LPA, both the Blue Line and the Expo Line havebeen modeled with five-minute peak: headways on the proposed Hill Street alignment. We have also modeledthese headways on the proposed Flower Street alignment. Due to operating conditions that result inunacceptable vehicular traffic disruptions at the Hill Street and Washington Street intersection the Hill Streetoption has been omitted from further discussion in this letter.During the process of exploring operating options for the Expo Line, it was discovered that the MTA intends toimplement a four-minute headway on the Blue Line in 2009, as documented by the MTA Rail FleetManagement Plan dated January 31,2003. To account for this, simulations have also been conducted to showthe impacts of operating a four-minute peak: headway on the Blue Line while operating a five-minute peak:headway on the Expo Line. It is important to note that these two headways are fundamentally incompatibleand result in significant and regular operating delays.The results of these operating simulations indicate that there are significant challenges to the operation of bothlines concurrently through the Flower Street and Washington Street intersection. In addition, there is strongevidence that the current configuration of the 7th & Metro Center terminal will not provide sufficient capacityto meet the needs of both the Blue Line and the Expo Line, and provide MTA Operations with the neededflexibility to respond to operating contingencies. Our analysis indicates that under normal operating conditionsthe capacity constraints may be manageable with disciplined operations using the five-minute headwayidentified in the LPA. However the practice will result in operational delays and sacrifice the flexibility thatthe MTA needs to regulate headways and mitigate technical failures and delays. It is clear that a reduction ofthe Blue Line's headway to four-minutes will make shared use of the terminal in its current track and platformarrangements insufficiently reliable for good operating practice.These results have been shared on separate occasions with staff from the MTA's Engineering and OperationsDepartments and have been met with general concurrence. The findings of our analysis are documented inmore detail below, organized by the particular areas of concern. At the conclusion of each of the discussions

707 Wilshire Boulevard, Suite 3300 Los Angeles, California, 90017 Tel (213) 922-9500 Fax (213) 922-9559


2/4

Mr. Steve BryeJune 4, 2003Page 2 of4

Mid City/Exposition LRTProjectPETeam

we have included potential design modifications that may serve to mitigate or eliminate the current challengesand may merit further investigation.Flower Street and Washington Street IntersectionLight rail operations have been simulated with the Expo Line operating at a five-minute headway and the BlueLine operating at both a five-minute headway and a four-minute headway. As simulated with both linesoperating on a five-minute headway, the delays experienced by Blue Line trains operating during the PM peakperiod at the Flower and Washington intersection range from zero to 80 seconds with an average of around 30seconds.Under the current operating conditions, as observed empirically, Blue Line trains are extremely challenged tohold schedules and maintain consistent five-minute headways during peak operations. It is not uncommon forpairs of trains to be observed entering the Metro Center Station at headways as short as 90 seconds. In theevent that the first train in a pair of trains operating at a 90 second headway were held at the Flower andWashington intersection, the second train would be unable to advance to the platform of the Grand Station forover a minute and a half. In fact, due to the train length of approximately 270 feet, the second train would beforced to wait as far back as the Main Street intersection before proceeding. This occurrence has the potentialto impact Blue Line operations along the entire portion of street running.This scenario becomes more likely with the advent of four-minute headways operating on the Blue Line whilethe Expo Line maintains five-minute headways. The combination of a four-minute headway with a five-minute headway will ensure that even under the best conditions, trains will be delayed by an intersection meetapproximately every 20-minutes.On the Expo Line, with both lines operating a five-minute headway, delays experienced at the intersection aremuch worse than those of the Blue Line. The delays range from zero to 191 seconds with an average of 51seconds. While traffic signal delays in street running may be routinely as long a 60 seconds, a delay of overthree minutes is considered extremely long. This worst-case delay is generated when a northbound Blue Linetrain holds the signal and is met by a Southbound Blue Line train just after clearing the intersection. This is anoccurrence that becomes more likely in the advent of four-minute headways on the Blue Line.There are several options that merit consideration in trying to mitigate or eliminate these intersection conflicts.These options include:

The use of train-to-wayside communications in combination with a vehicle identification system andtraffic signal preemption to control the intersection and assign priority to trains in order to reduceconflicts and increase intersection throughput. This option is likely to be technically challenging andmay result in only partial improvements.

The use of a half grade separation on the Expo Line to eliminate the diamond crossover. The use of aggressive pre-emption of traffic signals along the street running portion of the Blue Line inorder to properly meter and maintain headways. This option may have significant impacts on vehiculartraffic and may be met with significant resistance by the LADOT. The use of a separate alignment.


3/4



7th & Metro Center TerminalCurrently, during the PM peak, the 7th & Metro Center Terminal operates at an effective headway of five-minutes, accommodating 12 trains per hour. Due to the street running portion of the alignment, this effectiveheadway of five-minutes varies significantly from schedule. Trains were observed to routinely arrive at theterminal as close together as 90 seconds and as far apart as nine minutes. Additionally, MTA operations usessignificant platform and pocket track dwells to maintain a proper schedule for the departure of southboundBlue Line trains. Both of these factors combine to require the routine use of both platforms and pocket tracksto regulate Blue Line operations.The terminal simulations determined that when using a headway of five-minutes for both the Blue Line and theExpo Line, the best operating scenario is to dedicate a platform to the operation of each line. Under thisscenario, each train enters the terminal and berths at its designated platform, (e.g., platform #1 for the BlueLine, platform #2 for the Expo Line). At the platform, the train dwells for 60 seconds while passengers alightand board, and a drop back operator assumes control of the train from the departing end. This operatingscenario eliminates the use of the pocket tracks in routine operations and leaves one free to accommodate aspare train. The results of this simulation indicate that trains on the Blue Line may experience total delaysentering and leaving the terminal of up to 96 seconds while Expo Line trains experience delays of up to 62seconds. More critically, the delays experienced by inbound passengers awaiting access to the terminalplatform may be as high as 60 seconds for the Blue Line.While this simulation may accommodate both lines with manageable delays, it ignores several operatingfactors that decrease the capacity ofMT A operations to recover from contingencies and regulate operations:

The maximum dwell of 60 seconds means that trains will depart from the terminal at essentially thesame headways at which they arrived. In some instances this may be as close as 90 seconds, which willimpair the MTA's ability to reestablish proper headways

A train that needs to be taken out of revenue service will exceed the minimum dwell, which may causedelays in excess of those mentioned in the preceding paragraph, depending on the nominal headway ofthe following train

Under the current configuration, the tail tracks can only accommodate one spare train that must coveroperations for both lines because one tail track must be left vacant to accommodate any being removedfrom service Any technical problems experienced in or around the platforms and the front crossover may result inserious or non-recoverable delays to Expo and or Blue Line operations.

There are several options that merit consideration in trying to mitigate or eliminate these terminal restraints.These options include:

The use of aggressive pre-emption of traffic signals along the length of the Blue Line in order toproperly meter and maintain headways. Again, an option that is likely to be unacceptable to theLADOT The use of advanced communications systems to determine and respond to variations in nominalheadways by varying platform dwells. A solution that may result in improvements to normal

operations but will do little to provide relief or recovery from unusual operating contingencies


4/4


Extending the existing tail-tracks to accommodate an additional train The construction of a third platform track at the terminal A separate alignment.


RecommendationsThe PE Team believes that the results of our analysis as described herein suggest a change in emphasis on theBranching Study in order to ensure that a viable Exposition Corridor Project is developed. We propose thefollowing:

1. Further analysis of the Hill Street alternative be halted, based upon the untenable shared use delayslikely to be experienced by Blue Line service, Expo service, and area automobile traffic.

2. Further analysis of the Flower Street alternative be suspended, pending the results of No. 4 below,based upon the untenable shared use delays likely to be experienced by Blue Line service and ExposervICe.3. Further analysis of the Figueroa Street alternative be directed towards a surface alternative

terminating in the vicinity of 7th and Flower, most probably in the parking lot behind the 818Building.4. New analysis of physical improvements to the 7th and Flower Street Station and the junction of the

Blue Line and Expo Line services be modeled and ROM costed. At the present time, the PE teamfeels three potential modifications should be evaluated;a) the addition of a third track, effectively creating a center platform configuration for one of theexisting Blue Line platformsb) the extension of the tail tracks northward under Flower, creating additional storage capacity tostage trainsc) the addition of half grade separated operations in the vicinity of Washington Street

The PE team is available to discuss these recommendations and the supporting analysis. We are aware of theimportance of these decisions to the project. We believe a rapid decision on these recommendations is vital toour achieving the overall project schedule.Sincerely,

Step~echronisProject Directorcc:

EssamAlyAl WitzigAaron ForesmanChron file

Matt SweeneyEric OlsonMichael Harris-GiffordProject files 202.2, 491.3

Flower Street Memo

Documents

Transcript of Flower Street Memo