Horizontal Alignment Tool

1 Choose a method

Calculation method

MDOT MMUTCD RCOC

MMUTCD (2025)

Device selection, advisory plaques, chevron and delineator spacing, advance placement, and standard sizing use the selected source. MDOT delineators use R-127-I (2025).

2 Enter road and speeds

Roadway type — MDOT / MMUTCD (required)

Used by the selected method for sign sizing and applicable ramp rules.

Freeway vs. expressway

Freeway: A divided highway with full access control. Traffic enters and leaves by ramps; there are no at-grade intersections or driveways.

Expressway: A divided highway with partial access control. It may have at-grade intersections or limited direct access.

Choose based on how vehicles enter and leave the road.

Source: MUTCD §1C.02 — definitions (PDF)

MMUTCD roadway class (Table 2C-4)

RCOC road type — chevron size only RCOC classification (optional)

Sets only the RCOC chevron size shown in results. Roadway classification, device selection, and spacing use the inputs above.

Roadway surface

AADT category (MMUTCD device need)

Need counts? SEMCOG Traffic Volume Map

Approach-speed basis

Approach speed (mph)

Study advisory speed (mph)

Advanced options

Adjust placement, treatment exceptions, or study-support inputs. Existing values apply when this section is closed.

Show optional advance-warning placement

MMUTCD 5-mph differential on paved roads

Urban street with AADT at or below 1,000 Use MMUTCD omission option when eligible

§2C.06: speed limit ≤20 mph, or urban street with AADT ≤1,000.

Site advance-warning distance (ft, optional)

Shoulder width (ft)

Delineator offset beyond shoulder (ft)

Delineator layout sides

Road width (ft)

Device placement mode

3 Place three map points

Follow the road centerline: 1. Start of curve → 2. Midpoint → 3. End of curve.

Tap the map to place three points on the road centerline.

4 Review results

Chevron sizing details: RCOC and selected method

RCOC chevron sizing (W1-8)

Local roads: 18 × 24 in. Primary roads: 24 × 30 in. Dimensions are width × height.

Source: RCOC local/primary practice supplied for this calculator.

RCOC sizing is not selected.

Selected-method chevron sizing (W1-8)

Select a road type above.

Source sections

The MDOT signing guide is dated 2023; MDOT delineator detail R-127-I is dated October 24, 2025; the MMUTCD is the 2025 edition. Each result cites its selected source. PDFs retain the original pages and notes.

RCOC method: MMUTCD base with local/primary chevron sizes. Sizes follow the RCOC practice supplied for this calculator.

Sign images are from the Manual of Traffic Signs, by Richard C. Moeur. Advisory-speed plaques adapt the W13-1P artwork (PDF) with the selected speed.

Map legend

Chevron position
Delineator position
Advance-warning placement

Both device layouts are shown. See outputs for the recommended treatment.

Curve geometry

Selected points (1–3)
Curve arc
Fitted circle and center
Tangents and intersection
Tangent extensions
Chord (point 1 to 3)
Sample-point segments