RailSingleTrack

The RailSingleTrack subassembly is used to insert the rails, ties, ballast, and subballast for a single-track railroad.

It should be followed with a Daylight subassembly on the left and right sides to close to existing ground in cut and fill situations. It is capable of responding to rail cant.

Attachment

By default, the attachment point is at the centerline between the rails. The track can be moved relative to this point using the subassembly parameters.

Input Parameters

Note: All dimensions are in meters or feet unless otherwise noted. All slopes are in run-over-rise form (for example, 4 : 1) unless indicated as a percent slope with a “%” sign.

Parameter

Description

Type

Default

Measure Cant At Determines whether the elevation difference between rails takes place between the gauge line (face) of each rail or CL of each rail. Selection List:
  • Gauge Line to Gauge Line
  • CL Rail to CL Rail
CL Rail to CL Rail
Default Cant The default elevation difference between rails. The value is positive when the right rail is higher than the left and negative when the right rail is lower than the left. This value is applied in layout mode and is helpful for observing how the subassembly reacts to different cant values. This value is overridden by cant when it is present via the baseline alignment. Numeric 0
Gauge The distance between the inside faces of the rails. Numeric, non-negative

56.5"

1435 mm

Rail Head Width Width of the rail head. Numeric, non-negative

2.72"

69 mm

Rail Depth Depth of rail from top of rail to top of tie plate. Numeric, non-negative

6.625"

168 mm

Rail Base Width Width of the base of the rail. Numeric, non-negative

5.5"

140 mm

Tie Plate Thickness Thickness of the tie plate which is also the distance from the bottom of the rail to the top of the tie. Numeric, non-negative

1"

25 mm

Rail Base to Ballast Distance from the bottom of the rail to the top of the ballast. If this value is equal to the tie plate thickness, then the top of the ballast is flush with the tops of the ties. Numeric, non-negative

1"

25 mm

Tie Length Length of the tie (also known as sleeper). Numeric, non-negative

8.5 ft

2.59 m

Tie Depth Depth of tie . Numeric, non-negative

7"

178 mm

Minimum Ballast Depth The minimum vertical distance between the bottom of the tie and the top of the subballast. The location of this minimum distance changes at different stages in cant. See "Behavior" below. Numeric, non-negative

12"

305 mm

Ballast Shoulder Width (Left and Right) The distance from the end of the tie to the beginning of the ballast side slope. Numeric, non-negative

12"

305 mm

Ballast Side Slope (Left and Right) The slope of the side of the ballast material. The slope of the top of the ballast material matches the slope of the tie that results from cant. Slope, non-negative 2:1
Subballast Depth The depth of the subballast material Numeric, non-negative

8"

203 mm

Subballast Top Slope The top slope of the left and right sides of the subballast with the centerline of the subassembly as the hinge point. Slope, non-negative 40:1
Subballast Extension (Left and Right) The distance from the toe of the ballast material to the beginning of the side slope of the subballast material. Numeric, non-negative

12"

305 mm

Subballast Side Slope (Left and Right) The slope of the side of the subballast material. Slope, non-negative 2:1
SubBase Extension (Left and Right) The distance from the toe of the subballast material to the beginning of the side slope of the subbase material. Numeric, non-negative

0.5 ft

0.15 m

SubBase Slope The slope of the side of the subbase material. Slope, non-negative 1:1
SubBase Depth The depth of the subbase material. Numeric, non-negative

1 ft

0.30 m

Soil Fill Depth The depth of the soil fill material. Numeric, non-negative

1 ft

0.30 m

Soil Fill Slope The slope of the side of the soil fill material. Slope, non-negative 1:1
Soil Fill Extension (Left and Right) The distance from the toe of the subbase material to the beginning of the side slope of the soil fill material Numeric, non-negative

0.5 ft

0.15 m

Omit Rails Prevents the rail points, links, and shapes from being drawn. Yes/No No
Omit Tie Prevents the tie points, links, and shapes from being drawn. Yes/No No
Omit Ballast Prevents the ballast points, links, and shapes from being drawn. If this option is set to "Yes" then the subballast is also not drawn. Yes/No No
Omit Subballast Prevents the subballast points, links, and shapes from being drawn. If the Omit Ballast option is set to "Yes" then the subballast is not drawn regardless of this setting. Yes/No No
Omit SubBase Prevents the subbase points, links, and shapes from being drawn. If the Omit Ballast or subballast option is set to "Yes" then the subballast is not drawn regardless of this setting. Yes/No No
Omit Soil Fill Prevents the soil fill points, links, and shapes from being drawn. If the Omit Ballast, subballast, or subbase option is set to "Yes" then the soil fill is not drawn regardless of this setting. Yes/No No

Target Parameters

This section lists the parameters in this subassembly that can be mapped to one or more target objects. For more information, see To Specify Corridor Targets.

Parameter

Description

Status

Left Track Offset

May be used to set the horizontal location of the centerline of the left track.

Optional

Right Track Offset

May be used to set the horizontal location of the centerline of the right track.

Optional

Left Track Elevation

May be used to set the elevation of the center point between the left rails. Cant is applied after this point is located so the actual point between rails may vary since rotation can occur around either of the rails.

Optional

Right Track Elevation

May be used to set the elevation of the center point between the right rails. Cant is applied after this point is located so the actual point between rails may vary since rotation can occur around either of the rails.

Optional

Runtime Logical Assignments

None.

Output Parameters

None.

Behavior

When no targets are applied, the location of either track is determined by the Left Track Offset, Right Track Offset, Left Track Elevation Difference, and Right Track Elevation Difference. These values locate the center points between the tracks. By default, the Left Track Offset is zero, placing the centerline of the left track at the baseline. When target alignments and profiles are applied, these values are overridden.

Note: Please note that when using target alignments for the track centerlines, the tracks always remain perpendicular to the baseline, not the target alignment. When the target alignments are not parallel to the baseline alignment, distortion will occur and the track dimensions will not be accurately represented.

When rail cant information is applied to the alignment baseline, the rails will rotate accordingly. The point about which they rotate will depend on the setting for Pivot Method contained in the cant information for the alignment. If the Pivot Method is set to Low Side Rail, then the rail on the inside of the curve is held at track elevation and the elevation of the outside rail is adjusted an amount equal to the cant value.

Case 1: Pivot Method set to Low Side Rail

If the Pivot Method is set to Low Side Rail, then the rail on the inside of the curve is held at track elevation and the elevation of the outside rail is adjusted an amount equal to the cant value.

Case 2: Pivot Method set to High Side Rail

If the Pivot Method is set to High Side Rail, then the rail on the outside of the curve is held at track elevation and the elevation of the inside rail is adjusted an amount equal to the cant value.

Case 3: Pivot Method set to Center Baseline

If the Pivot Method is set to Center Baseline, then the both rails are adjusted an amount equal to half the cant value, the outside rail upward and inside rail downward.

For all cases, the Minimum Ballast Depth value is applied at the location of the minimum clearance between the tie and subballast. The subballast top slope is controlled independently by the Subballast Top Slope parameter. The location of the subballast crown is controlled by the Baseline to Subballast Crown parameter.

Rail Detail

The rail shape used in this subassembly is a simplified approximation of industry standard rail shapes and dimensions. Rail Head Width, Rail Depth, and Rail Base Width are available as input parameters and are used to derive the remaining approximated dimensions.

Layout Mode Operation

In layout mode the subassembly displays the links comprising the rails, tie, ballast, subballast, and side slopes.

Point, Link, and Shape Codes

The following table lists the point, link, and shape codes for this subassembly that have codes assigned to them. Point, link, or shape codes for this subassembly that do not have codes assigned are not included in this table.

Point, Link, or Shape

Code

Description

P1, P4 - P13 Rail Rail
P2 Cl_Rail Centerline of Rail
P3 Gauge_Line, Rail Gauge line (inside edge of top of rail)
P14, P18, P19, P23 Top_Edge_Ballast Top edge of the ballast material
P15, P17, P20, P22 Tie Top corner of tie
P16, P21 CL_Tie Centerline of tie at top
P26, P30 Top_Edge_Subballast Top edge of the subballast material
P27, P29 Bottom_Edge_Ballast Bottom edge of the ballast material
P28 Top_Subballast Top of subballast material at centerline
P31, P33 Bottom_Edge_Subballast Bottom edge of the subballast material
P32 Bot_Subballast Bottom of subballast material at centerline
P63 Bottom_SoilFill Bottom_SoilFill
P64 Top_Edge_SoilFill Top_Edge_SoilFill
P62, P65 Bottom_Edge_SoilFill Bottom_Edge_SoilFill
P66 Top_Edge_SubBase Top_Edge_SubBase
P67 Bottom_Edge_SubBase Bottom_Edge_SubBase
P68 Top_Edge_SubBase Top_Edge_SubBase
P69 Bottom_Edge_SubBase Bottom_Edge_SubBase
P70 Bottom_SubBase Bottom of SubBase
L1, L2 Top_Rail, Rail Top of rail
L3 - L13 Rail Rail
L14, L17, L22, L23 Ballast, Top Top of ballast
L15, L16 Tie, Top_Tie Top of tie
L18 - L21 Tie Tie
L24, L27 - L29 Subballast, Top Top of subballast
L25, L26 Ballast, Subballast Ballast and subballast
L30, L31 Subballast, Datum Bottom of subballast
L32 Ballast, Ballast_Between_Ties Ballast material in open space between ties. Can also be used when ties are omitted.
L67 - L70 Top, SoilFill SoilFill
L71, L72 SoilFill, SubBase SubBase
L73 - L76 Top, SubBase SubBase
L77, L78 SubBase, Datum SubBase
S1, S2 Rail Rails
S3 Tie Tie
S4 Ballast Ballast
S5 Subballast Subballast
S6 SoilFill SoilFill
S7 SubBase SubBase

Coding Diagram