Cross-County MetroLink Extension
Segment I
System and Alignment Design Concepts
Final Technical Report
Prepared for the
East-West Gateway Coordinating Council
in association with the
Bi-State Development Agency
Missouri Department of Transportation
By Parsons Transportation Group
and Associated Consultants
Draft: September 1998
Final: August 1999
Contents
List of Figures
List of Tables
This technical paper describes a series of possible system and alignment design concepts for the Segment I MetroLink extension. These concepts are to be reviewed and discussed with the expectation that a small set of candidate concepts will be selected for further study. The latter activity would develop the details necessary to identify location, operating characteristics, costs, and other impacts.
The ideas reflected in these possible concepts have been based on a review of previous cross-county corridor planning documents, regional transportation plans, and related technical information.
The task of defining possible alignment concepts has been undertaken in terms of a specific design context that portrays conditions in which this work is to be developed.
The context has four basic elements:
3
Project Goals and a Planning Framework
The study area for this design study, shown in Figure 1, extends from the vicinity of the existing Forest Park MetroLink station along the Forest Park Parkway/Millbrook Boulevard area to the Clayton CBD and then south along the CMT rail right-of-way to the I-44 area.
To begin considerations of possible broad design concepts, it is necessary to establish the planning goals that have been articulated for this major transportation investment. These goals define the comprehensive relationships between transportation, land-use, economic development and quality of life which are of highest priority to the citizens of the corridor and the region as a whole.
The following ten goals (See Table 1) represent an interpretation of prior planning activities and public discussion concerning the corridor. These goals are translated into various planning/design implications that give clarification and guidance to the design activities.
Using these preliminary goals as a guide, a three-part planning framework has been developed as a second step in the concept identification and development process. These parts are: (1) the functional principles for this MetroLink extension, (2) the urban design perspective for the corridor, and (3) the transit operational perspective.
Functional Principles
Segment I will expand the coverage area of the MetroLink system. This will increase the role that transit can play in the overall regional transportation system. MetroLink will intercept major travel corridors (e.g., along I-64 and I-44), offering a new alternative travel path for trips destined to Clayton, City of St. Louis CBD, Forest Park, and other important destinations. Segment I provides transportation service in the portion of the Cross-County corridor south of I-64 where no freeways exist or are planned. As such, it would add needed transportation capacity supplementing traffic capacity provided by major arterial streets (e.g., Brentwood Boulevard, Hanley Road, Big Bend Boulevard, and others).
Within this broad context, previous Cross-County planning documents and other plans (e.g., Master Plan for the Clayton Downtown) have articulated the functional principles for the proposed transit line, as follows:
Segment I would be constructed in a largely built-up urban corridor. In order to be an asset in the fullest sense, the engineering design must be guided by and be interactive with an urban design perspective or framework. Such a perspective would define critical relationships between land use and new transit facilities; cultural, historic, and architectural values to be respected and reflected by design; and overall quality, scale, and harmony in architectural themes and materials used in transit facilities.
Figure 2 illustrates an urban design framework for the corridor. This recognizes that the corridor contains highly distinctive areas. In general, these are:
Because of these corridor characteristics, the urban design framework includes both strategies to minimize the negative impacts that a transit facility could have on high-value residential neighborhoods to strategies that would seize upon the new transit accessibility to promote desirable growth and development.
The third part of the planning framework concerns operational perspectives. These address the operating relationship between Segment I and other parts of the MetroLink system (existing and future) and between Segment I and other modes.
Figure 2 - Urban Design Framework
As noted earlier, Segment I will extend from the existing MetroLink line at the Forest Park station. Further, it will be designed in a way to provide for future extensions: Segments II and III in the Cross-County corridor; and possibly West St. Louis County corridor.
The implication of these connections is both physical and operational, i.e.:
Based on previous Cross-County studies, the proposed Segment I may have at least nine stations, plus the Forest Park station. At each of these stations, local modes of access would need to be included in the design concepts. As a general planning perspective, such modal access by station would be as follows:
Another key aspect of multi-modal operations concerns the potential joint use of public street right-of-way. The LRT could be located at-grade on public streets. This would entail sharing the right-of-way with other traffic. At the broad concept level, this could include the following operating conditions:
Relative to the preceding item (b), this operating concept could include shared use lanes in which other traffic would travel along the track zone with LRT trains. This would be similar to the old street car trolley operation. However, to enhance LRT speeds (avoid delays from other traffic) and minimize accident potential, LRT trains could be kept separate. Travel along the track zone would, of course, be permitted for emergency access or in after-hours periods when LRT trains are not in operation and for track access, street maintenance, or other service purposes; but during normal operating hours, LRT trains would operate in their own lanes.
Joint use in public streets would also include special operations at traffic signal intersections. In this location, LRT trains would pass through the intersection under their own signal phase (e.g., their own "green" light). Such LRT signal phases could be given priority over signal phases allocated to movements by other traffic.
At other locations, where traffic signals do not exist and are not warranted, street crossing of the LRT tracks would be operated similar to a railroad crossing with gates and warning lights. Other traffic would be stopped for the LRT train.
Finally, there is another multi-modal aspect to the concept design. This concerns possible shared use of right-of-way for bike/pedestrian paths and trails. In locations such as the CMT right-of-way, it may be possible to integrate paths and trails along with the LRT tracks. Such paths and tracks. Such paths and tracks would be separated from the LRT tracks with fencing or other barriers for safety reasons
Other documents prepared for this project will describe detailed design polices and standards. For the purposes of a concept discussion, certain design policies/standards need to be highlighted at this point because of their impact on concept identification.
The LRT will use space within streets and other available right of way. The following design standards should be used to guide concept development.
The above dimensions represent current MetroLink (BSDA) standards.
Recognizing the topographic conditions of the study area, the alignment concepts will need to include various sections in which the LRT tracks will be on vertical grades.
Overall, the selection of grades is a very sensitive matter because of its affect on LRT speeds, operating efficiency, safety, and cost. Further, the effects of weather is a significant consideration in choosing the proper slope for LRT tracks.
Current Bi-States Development Agency standards prescribe a preferred grade of 3.5 percent, and a maximum grade of 6%, i.e., vertical grade change of 3.5 to 6 feet vertically for 100 feet of horizontal distance. At each end of an upward slope in the LRT tracks, a proper vertical curve must be included to provide needed "rounding" of the transition between changes in vertical slope.
From the perspective of national design experience, other transit agencies (e.g. Baltimore, Pittsburgh and Portland) define similar standards in the 4 to 7% range. Some agencies (e.g. Pittsburgh) allow grades up to 9%. These are used with caution and are applied to short lengths of track (up to 500 feet long).
Thus, typical changes in grade from ground surface to under ground (e.g. cut and cover construction) or vice versa will require 600 to 800 feet in horizontal distance. For a possible underpass at a major cross street (e.g., Skinker at Forest Park Parkway), the total length of transition from ground surface to under the cross street and back to ground surface would require approximately 1,700 feet (assuming no station/stop). Another situation could entail rising from ground level to the elevated CMT right-of-way. This would require 600 to 800 feet of horizontal distance to accomplish the grade change.
The above dimensions are approximate, since they do not reflect the specific elevations of corridor topography or the impacts of utilities, which could require that LRT underpasses or below-grade alignments be deeper (i.e., to allow utility lines to pass over the top of the LRT structure). If the LRT tracks must be deeper, it would require more distance to make vertical grade changes.
Another important reality of LRT grade changes is the presence of "transition structures." These are the facilities required to support the sloped sections of track where vertical grade changes are being made. When the LRT is going to an above-grade alignment (above ground), transition structures are the "bridges" supporting the tracks as they go uphill. For most of the length of such structures, other traffic cannot cross underneath because the clearances would typically be too low. When LRT is going below ground, the transition structures are the retaining walls that surround the "hole in the ground" through which the tracks pass as they descend underground. Again, these retaining walls typically block other traffic from crossing over the track zone.
The need for transition structures requires careful planning and location of grade changes. In some locations, the transition structures could cause unacceptable impacts on other traffic or land use functions.
Finally, the LRT track needs to adhere to certain standards concerning horizontal curvature. LRT technology has the flexibility to operate high speeds (55 mph) or at slower speeds (e.g. 25-35 mph) when in an at-grade/street location. Horizontal curvature is a function of the specifics of the location and the turning capabilities of the equipment. The selection of curvature has a significant impact on LRT speed and operating efficiency; and is a very important design consideration.
As an indication of the range of possible curvature, the following should be considered; in consists of up to six cars the minimum horizontal curve radius will not be less than 82 feet and not less than 296 feet in tunnel areas. Also, when switches are used for diverging LRT movements, the recognized industry standard (practice) is that switches are to be located on tangent track sections, not on curved track.
To provide specific information for planning, various land-use, transportation, topographic, ad right-of-way inventories have been made. These have recorded key existing conditions and identified certain opportunities and constraints that are relevant to design concepts. These results are briefly summarized here.
Figure 3 summarizes essential information about the transportation systems relative to the street system, current traffic volumes, and the configuration of Bi-States bus routes in the corridor. The key findings are as follows:
Figure 3
Transportation Systems
In addition to the above which summarizes existing conditions, previous planning studies included estimates of potential future conditions. The latter included ridership estimates for the Segment I MetroLink extension. Results were as follows for estimated yr. 2015 conditions:
Figure 4, summarizes principal topographic information in terms of elevation data for various points in the corridor. This indicates the significant elevation changes, especially in the Clayton CBD.
Streets in the Clayton CBD have some sections where grades are in the 6 to 10% range. This affects Forsyth, Carondelet, Bonhomme, Brentwood, and Meramec. This means that grades are near the limit of safe and reasonable design for LRT.
Current LRT equipment specifications used by BSDA require trains to negotiate vertical grades up to 7%. Further, the change in grades, for track design, requires the use of vertical curves to "round-off" the transition. Such curves could cause significant differences between track level and the grade of the adjacent roadway pavement. These conditions will need to be examined in more detail to identify these relationships as they would affect the design of LRT with an at-grade concept.
As discussed earlier in this report, the LRT will be located on a combination of rights of ways - some in public streets and a significant portion in the CMT right of way or easement.
Figure 5 illustrates key features of the CMT right of way/easement. It is largely an above grade embankment. This means, it goes over crossing streets. The one exception is I-64 where the CMT is under the freeway.
The right of way/easement ranges in width generally from 40' to 100'. The significant feature of the CMT right-of-way is that Union Electric has located a high voltage electric transmission line in the right of way/easement. This line includes tall, steel towers that are located throughout the length of the right of way/easement from Forest Park Parkway to I-44. The poles are generally located in the center of the right-of-way. The specific distance from edge of right-of-way varies from pole-to-pole. The LRT design will need to identify where/how the tracks can safely pass by these towers. It may be necessary to consider relocation of poles where an appropriate alignment can not be developed.
6
System and Alignment Design Concepts
All of the preceding discussion is a preamble to the discussion of a set of possible system and alignment design concepts.
The concepts are described in terms of the three geographical area, i.e., (1) Forest Park station through University City; (2) Clayton and the Galleria Area; and (3) Richmond Heights to Shrewsbury. This is done because the conditions in each area are significantly different. Furthermore, the choice of concept in one area is somewhat independent from that for the other two areas. However, at the boundaries between segments, alignments need to fit together to form a compatible alternative for the entire corridor.
Within the corridor, as defined by Figure 1, there is a combination of streets, which could be used for the alternative concepts. Along with these horizontal locations, there are various possible vertical locations. The task of identifying concepts is to merge horizontal and vertical locations together.
The possible horizontal locations are depicted by the various right-of-way opportunities. Figure 6 illustrates all of these locations in the corridor. In the Forest Park and Clayton areas, there are several possible choices (i.e., not all streets shown would be used for an alternative concept). In the Richmond Heights to Shrewsbury area, the location is primarily the CMT right-of-way/easement, except for some alignment alternatives south of Big Bend Boulevard.
Along with horizontal location, there is a set of five basic vertical location concepts as follows (see Figure 7):
Figure 6
Potential LRT Locations
These vertical alignment concepts have uniquely different impacts on LRT construction, operation, and cost as well as varying impacts on the surrounding community.
Using these concepts for overall planning purposes, it is possible to identify certain combinations of horizontal location with vertical design types. The following matrix suggests combinations that would be reasonable for each area of the corridor.
Area
Elevated
Surface
Below Grade
(Cut & Cover)
Below Grade
(Open Cut)
Below Grade
(Tunnel)
Forest Park Station through University City
Not Desirable
Possible
Possible
Possible
Not Necessary
Clayton and the Galleria Area
Not Desirable
(but possible)
Possible
Possible
Possible
Possible
Possible
Not Desirable
Not Desirable
Possible
Not Necessary
Richmond Heights to Shrewsbury
Possible
Possible
Limited Application
Limited Application
Not Necessary
Based upon these overall combinations, a set of specific alternative concepts have been identified for discussion. These are summarized by Table 2. Highlights of these concepts are discussed in the following section.
Forest Park Station through University City
The horizontal alignment is basically the same for all alternatives in that the Forest Park Parkway and Millbrook Boulevard rights-of-way are involved. There are possible options concerning the placement of tracks in the right-of-way.
The alternative concepts could be:
Figure 8
Forest Park Station through University City - Possible Surface Locations
(FPP - Possible Location of Surface)
Figure 9
Typical Cross Sections - At-Grade
(Clayton - Possible Location of Surface)
Figure 10
Forest Park Station through University City - Possible Below-Grade Locations (South/I-44-Possible Location of Surface)
For each of these options, the plans would be coordinated with possible new development being considered in the vicinity of the Forest Park station by BSDA. Such development would reflect transit-oriented land-use concepts in which convenient and attractive linkages to MetroLink and other transit would have high priority.
There are a number of possible combinations of horizontal and vertical alignments. These schemes reflect a key conclusion that has resulted from the review of previous planning documents: alignments penetrating Shaw Park are omitted. At-grade alignments in Shaw Park would have a highly disruptive effect on activities and physically impact parkland. Underground (cut and cover) would have a negative impact on existing vegetation (primarily the many large trees).
Tunneling could be considered, but would be very expensive. Furthermore, the alignment still must reach the CMT right-of-way, which is above grade (not at ground level). For a tunnel or below-grade (cut and cover) alignment, the length of the transition structure would make the Shaw Park location impractical. The structure, if built, could extend through a significant part of Shaw Park.
For this area, the alignment concepts can be considered in three sections: through the Clayton CBD core, connecting the Clayton CBD core to the CMT right-of-way, and location of the Galleria station.
Figure 11
Clayton and the Galleria Area - Possible Surface Locations
(Clayton - Possible Location of Elevated)
Figure 12
Clayton and the Galleria Area - Possible Elevated Locations
(South/I-44 - Possible Location of Elevated)
Figure 13
Clayton and the Galleria Area - Possible Below-Grade Locations
(Forest Park Parkway - Below Grade (Cut & Cover or Open Cut)
Option 2: Continue along Forsyth (at-grade or below grade) to Brentwood and turn onto Brentwood and continue south (at-grade or below grade). At a point, south of the Bonhomme intersection, the underground alignment option tracks would emerge at grade surface and continue at grade to Forest Park Parkway.
A below-grade option for this alignment would not be possible because of insufficient length to change vertical elevation. The alignment could be below grade (cut and cover) at Brentwood and extend west, parallel to the parkway. It would need to go under the parkway to then rise up to the elevation of the CMT track bed. This change would need to be placed north of the CMT bridge over Brentwood Boulevard. There is not sufficient length to achieve this change.
Brentwood Boulevard. The alignment could have five options:
Option 1: At-grade on Brentwood Boulevard, from approximately Bonhomme Avenue, with both tracks on the west side of the road. At a point just south of the Clayton Corporate Center's main drive, the tracks would start rising on structure, with a curve up to access the CMT right-of-way north and west of the CMT-Brentwood Boulevard bridge.
Option 2: This is similar to option 1 except that the tracks would be in a median location. The elevated section would swing into the CMT via a alignment through an area on the east side of Brentwood Boulevard, i.e., the southeast corner of Brentwood and Watkins.
Option 3: At-grade on Brentwood (from Bonhomme) with both tracks in a median location; the tracks would extend south on Brentwood Boulevard through the Clayton Road intersection to Galleria Parkway, and east on Galleria Parkway to the CMT right-of-way.
Option 4: Underground (cut and cover) along Brentwood Boulevard, extending south to Galleria Parkway and east to the CMT right-of-way.
Option 5: At-grade on Brentwood Boulevard (from Bonhomme) to Shaw Park Drive, west along north side of Forest Park Parkway with rise to an elevated section over Forest Park Parkway to the CMT right of way in the vicinity of the City of Clayton public works yard.
In these sections along Brentwood Boulevard (north of Clayton Road), there would be no stations.
Richmond Heights to Shrewsbury Area (See Figures 15, 16 and 17)
For the section from Galleria Parkway south to Big Bend Boulevard, there is only one basic alternative: in the CMT right-of-way. There could be specific location adjustments in this area in terms of the location of the electric transmission line towers and the LRT tracks.
Figure 14
Typical Cross Section - Elevated
(Clayton - Below Grade (Tunnel))
Stations would be located at Eager Road and at Manchester Road. At Eager Road, there is a potential for joint development involving the expansion of retail and office land uses. A major park-n-ride facility would be considered. Traffic access needs for such a facility could require significant roadway modifications. The Manchester Road station would be located to conveniently access major industrial land uses.
In the section thru the Sunnen Business Park (Flora Avenue to Union Pacific Railroad), there are two options: (1) below grade (cut and cover); or (2) elevated. Consideration of open cut or surface alignments would not be feasible, given the layout of the development and ground level site roadways and parking areas.
Further south at Big Bend Boulevard, a station would be located to link to the commercial center in the area just north of Deer Creek. It is possible that this station could be the southern terminus. Park-n-ride facilities could be located in this vicinity.
The alternative would be to continue Segment I further south. A significant consideration for this southern terminus is freeway access to and from the west on I-44. These ramps are missing at the existing Shrewsbury Road/I-44 interchange. Ramp access is available further west at Laclede Station Road, but do not provide the direct, convenient access essential to the new LRT station, for both park-n-rider and bus transfer patrons.
Concepts include two significant elements at this point in the corridor: (a) the extension of the LRT tracks over I-44 to a convenient terminus in Shrewsbury and (b) a freeway interchange modification.
For the LRT track alignment, the tracks could follow two options: (1) the CMT alignment over Deer Creek and over I-44 at a point just east of the gas reservoir to the rail right-of-way (BNSF) just west of the River Des Peres, or (2) be combined in a right of way with a new major arterial street linking Big Bend Boulevard (at Oxford) to River Des Peres Boulevard at Lansdowne Avenue. The terminal station for Segment I could be just north of Landsdowne Avenue. The area between I-44 and Landsdowne just west of the River Des Peres could be a joint development opportunity. A park-n-ride and major Bi-State Bus transfer center could be located in this vicinity.
For the freeway interchange modification, three basic alternatives could be considered:
Along with the alternative alignment concepts discussed above, there are possible alternatives associated with the number and location of LRT stations. These possibilities could be:
1. This represents a special case in that major parking facilities exist in the Clayton CBD. St. Louis County is planning a new parking structure. Users of such parking could transfer to MetroLink at the Clayton CBD station.
Vertical Alignment Concepts


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