14.1 Stationing and Stake Marking

14.1 Stationing and Stake Marking

Quick Answer: 1 station = 100 ft. 1,327.50 ft ahead of Sta 10+00 is Sta 23+27.50. Cut = hub elevation − grade elevation: hub 428.62 ft, grade 426.15 ft → C 2.47. A station equation gives the same ground point two names (BK behind you, AHD ahead of you). The hub is the measured point; the lath carries the writing.

Domain V (Construction Surveying) is 20% of the 2022 CES test plan. This chapter is items A and B — staking procedures and critical cross-section points — which is half of that domain. Item C (setting points on horizontal and vertical curves) is Chapter 15. Under BPC 6731.1(a), a California civil engineer may locate and establish alignment and elevation for the fixed works in BPC 6731. That is this work. Right-of-way monuments that mark property lines remain land-surveying practice.

Station Language

A full station is 100 ft of horizontal distance along the stationing line (usually the construction centerline or a named alignment such as the “A” line). The plus is the leftover feet inside that 100-ft interval.

Half stations on a construction job are the 50-ft marks (10+50, 11+00, 11+50). Many roadway crews also set 25-ft marks on sharp curves, flat grades, and curb returns. The plus is still feet, not a decimal station: 10+13.275 would mean 13.275 ft past 10+00, which is not how you encode 1,327.50 ft.

Highway stationing commonly starts at 10+00 (or higher) so a short revision off the beginning of the job does not produce a negative station. Always read the plans for the actual beginning station before you convert a distance.

Worked: 1,327.50 ft along the alignment

Given: a point is 1,327.50 ft ahead of the beginning of stationing, and the beginning station is 10+00.

Distance from 0+00 = 1,000 + 1,327.50 = 2,327.50 ft.
Full stations = 23; plus = 27.50 ft.
Station = 23+27.50.

If that same 1,327.50 ft is measured from 0+00, the station is 13+27.50. The exam trap is mixing those two beginnings. Convert feet to a plus with ÷ 100; do not treat stations as 10-ft or 1,000-ft ticks.

Offsets are measured left (LT) or right (RT) of the stationing line, normal on a tangent and radial on a circular curve, looking upstation (in the direction of increasing station). 15 ft LT at 25+50 is not 15 ft along the centerline.

Station Equations (Ahead / Back)

A station equation is one physical point with two station names. You arrive on the back (BK) station and leave on the ahead (AHD) station.

12+50 BK = 15+00 AHD

Ahead 15+00 is larger than back 12+50, so 250 ft of station numbers do not exist (a gap). Ground distance is shorter than the raw station subtraction.

Worked gap. Walk from 10+00 to 16+00 through 12+50 BK = 15+00 AHD:

• 10+00 → 12+50 = 250 ft
• Jump to 15+00 (no ground)
• 15+00 → 16+00 = 100 ft
• Ground distance = 350 ft

Naïve 16+00 − 10+00 = 600 ft is wrong by the 250 ft gap.

15+00 BK = 12+50 AHD is the opposite: ahead is smaller, so 250 ft of station numbers exist twice (an overlap). From 10+00 to 16+00 the ground distance is 500 + 350 = 850 ft.

On a lath at the equation, Caltrans-style abbreviations are BK and AHD. Compute every construction distance by breaking at the equation. Do not feed a spreadsheet a single start station and a single end station across the break.

Hub, Lath, Blue Top, Red Top, Finish Grade

Caltrans Surveys Manual Chapter 12 (November 2012) is the Department’s construction-staking playbook on State highway work. Department-furnished control stakes (also called grade stakes) establish basic line and grade. The Contractor’s working stakes come from those. Final grade stakes (FGS) are set once per grading plane and control the grading plane, subbase, base, and pavement together. Do not expect a new Department color for each lift.

Color (flagging / cards, Caltrans): grading — slope, rough grade, final grade — is yellow; drainage, curb, and gutter are blue; horizontal and vertical control is white/red; clearing is yellow/black; structures are white; right-of-way is white/yellow; signs and similar miscellaneous work are orange.

What a CE Writes on the Stake

The face of the marker shows the references to the feature. Distances are measured from the hub away from that face, along the cross-section (normal or radial). Typical civil markings:

GRADE answers “cut or fill to what?” OFFSET answers “is this hub the point, or only a witness?” Mixing them is how a crew grades the hub instead of the pavement.

Caltrans card order (top of stake = this reference, then the feature): alignment and station, offset to the stationing line (or CL if on line), elevation of the hub, then cut/fill and distance to the point being staked. If the plans publish an elevation for the feature, the stake shows hub elevation, not a cut/fill, unless the Resident Engineer directed a field adjustment.

Mark slope stakes, abutment-fill stakes, and rough-grade stakes to 0.1 ft. Mark other references to 0.01 ft. Slope ratios on California foot-unit jobs are horizontal:vertical (2:1), with no plus/minus on the ratio. Pavement cross-slopes are percent, signed from the stationing line out.

Worked: cut from hub to grade

Given: hub elevation 428.62 ft, design grade at the referenced feature 426.15 ft.

Cut = 428.62 − 426.15 = 2.47 ft. Mark C 2.47 and the feature (GRADE, FL, SG, …). The contractor cuts 2.47 ft from the top of the hub to the design surface.

If the hub is 219.10 ft and grade is 221.85 ft, fill = 221.85 − 219.10 = 2.75 ft. Mark F 2.75. Sign errors (calling 2.47 a fill because the number is “to grade”) invert the earthwork.

Density and Traps

Typical Caltrans longitudinal spacing (decrease when the Resident Engineer needs intervisibility): slope stakes 100 ft ( 50 ft on curves with radius < 1,000 ft, or when cut/fill > 10 ft); FGS 50 ft ( 25 ft when radius < 1,000 ft); curb 50 ft ( 25 ft when grade < 0.3% or radius < 1,000 ft).

Exam traps: (1) encoding 1,327.50 ft as 10+13.275 or as 13+27.50 when the alignment begins at 10+00; (2) subtracting stations across an equation; (3) measuring cut from the lath instead of the hub; (4) treating a blue top as a Caltrans Department-furnished color — Department grading is yellow, and bluetops are contractor working stakes; (5) writing 2:1 as vertical:horizontal.