MUTCD Rules Data¶
TrafficCAD does not link to the manual — it encodes it. Every distance a generated plan prints comes from the tables below, and every one of them carries its citation into the UI, the plan, and the exported PDF.
This page is the reference for what is encoded, so you can check a computed number against the source without opening the app.
Edition tracked: MUTCD 11th Edition, Revision 1 (December 2025).
State supplements override these
With a state standard selected, its supplement takes precedence where it differs from the national manual. Texas TMUTCD 2025 and California MUTCD 2026 ship as complete libraries — see State Standards & Libraries.
Taper length¶
Taper length L is computed from the posted or anticipated operating speed S and the lateral offset W, per Table 6B-4:
| Speed | Formula |
|---|---|
| 40 mph or less | L = WS² / 60 |
| 45 mph or more | L = WS |
Table 6B-3 then sets the required length for each taper type as a multiple of L:
| Taper type | Required length | Citation |
|---|---|---|
| Merging | at least L | Table 6B-3 |
| Shifting | at least 0.5 L | Table 6B-3 |
| Shoulder | at least 0.33 L | Table 6B-3 |
| One-lane, two-way | 50–100 ft | Table 6B-3 |
| Downstream | 50–100 ft | Table 6B-3 |
See Taper a Work Zone by Hand for the calculator that applies this.
Buffer space¶
Longitudinal buffer space equals stopping sight distance for the speed, per Table 6B-2. Buffer space is an Option in the manual; when it is used, these lengths apply.
| Speed (mph) | Buffer (ft) | Speed (mph) | Buffer (ft) | |
|---|---|---|---|---|
| 20 | 115 | 50 | 425 | |
| 25 | 155 | 55 | 495 | |
| 30 | 200 | 60 | 570 | |
| 35 | 250 | 65 | 645 | |
| 40 | 305 | 70 | 730 | |
| 45 | 360 | 75 | 820 |
Advance warning sign spacing¶
Distances A, B, and C between advance warning signs, per Table 6B-1, selected from the road context:
| Road context | A | B | C |
|---|---|---|---|
| Urban, low speed | 100 ft | 100 ft | 100 ft |
| Urban, high speed | 350 ft | 350 ft | 350 ft |
| Rural | 500 ft | 500 ft | 500 ft |
| Expressway / freeway | 1,000 ft | 1,500 ft | 2,640 ft |
Channelizing device spacing¶
Maximum spacing between channelizing devices, per §6K.01 ¶04–05:
- In a taper: 1 × speed in mph, as feet (45 ft at 45 mph).
- On a tangent: 2 × speed in mph, as feet (90 ft at 45 mph).
- In a 50–100 ft taper (one-lane two-way, downstream): approximately 20 ft, per §6B.08 ¶12/¶14.
Spacing a run at the taper maximum keeps the whole run compliant, since the tangent allowance is looser. See Channelizing Devices.
Other encoded rules¶
| Rule | Value | Citation |
|---|---|---|
| TTC speed reduction limit | 10 mph maximum | §6B.01 ¶17–20 |
| Minimum lane width | 10 ft; 9 ft short-term, low-volume / low-speed | §6N.07 ¶02–04 |
| Sign mounting heights | 5 ft rural, 7 ft urban/business, 1 ft minimum portable | §6F.02 |
| Portable low-mount signs | 3 days maximum (Guidance) | §6F.02 ¶11 |
| Crashworthy supports | Standard | §6F.02 ¶15 / §6A.04 |
| Flagger stations | Visible at the Table 6B-2 distance for the speed | §6D.06 |
| Arrow board requirements | By closure type and speed | §6L.06 |
| Type 3 barricades and sign coverage | Encoded per the barricade rules | §6K |
Typical applications¶
The MUTCD Chapter 6P typical applications (TA-1 … TA-54) ship as editable templates, and the closure classifier maps a drawn work zone to the applicable TA. See Typical Applications & Templates.
Reading a citation on a plan¶
Generated plans print the citation next to the value, in the form
MUTCD 11th Ed. Table 6B-4 or MUTCD 11th Ed. §6K.01 ¶04–05. If a
number looks wrong, the citation tells you exactly which table to check
— and the inputs that drove it (speed, offset, road context) are on the
road and the run that produced it.
Computed is not approved
Encoding the manual removes arithmetic errors, not engineering judgement. Every plan remains a draft requiring review and approval by a qualified engineer, per MUTCD §6P.01.