Driving safety guide · Ford of Peoria · Peoria, IL
Speed Limit Signs Explained
A Speed Limit sign looks simple, but the plaques around it, the yellow speed plaques on warning signs and the signs that warn of a lower limit ahead all mean different things. Here is what the federal Manual on Uniform Traffic Control Devices (MUTCD) says about them.
The short answer
A Speed Limit (R2-1) sign shows the regulatory limit set by law or by an engineering study, always in multiples of 5 mph, and it is posted where the limit changes. Plaques can add truck, night or minimum limits. A yellow speed plaque under a warning sign is an advisory speed for a condition such as a curve, not the speed limit.
The Speed Limit sign
A regulatory sign: regulatory signs tell road users about traffic laws or regulations. They are rectangular unless the MUTCD says otherwise, and white and black are the MUTCD color codes for regulation.
What it shows: the Speed Limit (R2-1) sign displays the limit established by law, ordinance or regulation, or adopted by the authorized agency based on an engineering study. The limits displayed must be multiples of 5 mph.
Where it goes: where posting is required by law, Speed Limit signs are placed at the points of change from one limit to another, and a sign showing the next limit is installed at the downstream end of each section. Statutory limit signs are required at entrances to the state and, where appropriate, at jurisdictional boundaries in urban areas.
Reminders: the MUTCD says additional Speed Limit signs should be installed beyond interchanges and major intersections, and anywhere drivers need a reminder of the limit.
Size: the MUTCD minimum size table lists the R2-1 sign at 24 by 30 inches for a single-lane conventional road and 48 by 60 inches for a freeway.
This page covers the signs. For the limits that apply on Illinois roads, see our guide to Illinois speed limits. Driving after dark? Read our night driving tips.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 1D.05, 2A.05, 2B.01, 2B.02, 2B.03 (Table 2B-1) and 2B.21, read November 4, 2026.
How speed limits are set
Two ways: the MUTCD says maximum speed limits are established statutorily, by state law for a class of road such as freeways or city streets, or as speed zones based on engineering studies. State statutory limits might restrict the maximum that can be set on a particular road.
Engineering studies: speed zones other than statutory limits shall only be set on the basis of an engineering study that considers the roadway context. Factors the study should consider include the roadside environment and land use, transit, parking, pedestrian and bicycle activity, lane widths, shoulders, grade, alignment and sight distance, the geographic context, at least 12 months of reported crashes, and the speeds of free-flowing vehicles.
The 85th-percentile speed: on a freeway, expressway or rural highway outside urbanized areas, the posted limit in a speed zone should be within 5 mph of the 85th-percentile speed of free-flowing traffic, once the other factors have been considered and found non-mitigating and speed-reduction measures have been considered to the extent practicable. On urban and suburban arterials and rural main streets, the 85th-percentile speed should not be used without considering all of the factors.
Reviews: agencies should restudy non-statutory limits on roads that have changed significantly, such as new lanes, parking, driveways, bike lanes or traffic volumes.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2B.21, read November 4, 2026.
Plaques and related signs
These plaques and signs work together with the Speed Limit sign:
| Sign or plaque | What it means |
|---|---|
| Truck, Bus or Vehicles over X Tons (R2-2P series) | A special limit for a class of vehicles. Shown below the Speed Limit sign, or combined into one sign below the SPEED LIMIT legend. |
| Night (R2-3P) | Where day and night limits differ, both must be posted. The night plaque should be white on black. |
| Minimum (R2-4P) / Maximum and Minimum (R2-4a) | A minimum legal speed, used only with a Speed Limit sign and mounted below it, or one combined sign with both limits. |
| CITYWIDE, NEIGHBORHOOD, RESIDENTIAL (R2-5aP to R2-5cP) and UNLESS OTHERWISE POSTED (R2-5P) | The limit applies to the whole city, neighborhood or residential area unless another sign says otherwise. Where a jurisdiction uses them, the area plaque may go above the sign and UNLESS OTHERWISE POSTED may go below. |
| FINES HIGHER (R2-6P), BEGIN / END HIGHER FINES ZONE (R2-10, R2-11) | Increased fines apply in a designated zone, such as a work zone or school zone. An END HIGHER FINES ZONE sign marks the end where a begin sign or plaque was used. |
| END VARIABLE SPEED LIMIT (R2-13) | May mark the end of a variable speed zone. |
| END TRUCK SPEED LIMIT (R2-14) | Required at the end of a truck speed zone that was announced with a Truck Speed Zone Ahead sign. |
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2B.21 to 2B.25, read November 4, 2026. The MUTCD says no more than three speed limits should be shown on one Speed Limit sign or assembly.
Signs that warn of a lower limit
Reduced Speed Limit Ahead (W3-5, W3-5a): a yellow warning sign that should be used where the speed limit is being reduced by more than 10 mph, or where engineering judgment indicates drivers need advance notice to comply with the limit ahead.
Variable Speed Zone Ahead (W3-5b): should be used before a zone where the limit varies by time of day or as conditions change.
Truck Speed Zone Ahead (W3-5c): warns of a reduced limit for trucks.
Then the limit itself: each of these warning signs must be followed by a Speed Limit sign at the beginning of the zone, and the speed on a W3-5, W3-5a or W3-5c sign must match the Speed Limit sign that follows.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2C.40, read November 4, 2026.
Speed limits vs. advisory speeds
Advisory Speed plaque (W13-1P): a yellow plaque that may supplement a warning sign, such as a curve warning, to show the advisory speed for that condition. It shall only be used to supplement an advance warning sign and shall not be installed as a separate sign. The speed shown must be a multiple of 5 mph, and except in emergencies or when the condition is temporary, the plaque is not installed until the advisory speed has been determined by an engineering study.
Not the limit: the MUTCD says a Speed Limit sign should not be used to warn of an advisory speed for a roadway condition; the advisory speed plaque is used for that.
Exit and ramp speeds: an Advisory Exit Speed (W13-2) sign must be used before a freeway or expressway exit where the mainline limit and the exit advisory speed differ by 20 mph or more, and should be used at 15 mph. Regulatory Speed Limit signs should not be placed near exit ramps or deceleration lanes, particularly where they would conflict with the advisory speed.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2B.21, 2C.12 and 2C.59, read November 4, 2026.
Variable and school speed limits
Variable speed limits: a variable speed limit sign may change the limit for traffic and ambient conditions. Its SPEED LIMIT legend is black on a white retroreflective background, and the number is shown in white LEDs on an opaque black background.
Speed feedback: a Vehicle Speed Feedback plaque may be mounted below a Speed Limit sign to display the speed you are traveling.
School zones: where a reduced school speed limit zone has been established, a School Speed Limit assembly or a School Speed Limit When Flashing (S5-1) sign shows the limit, a School (S1-1) sign is installed in advance of it, and an END SCHOOL SPEED LIMIT (S5-3) sign normally marks the end. The zone should begin at least 200 feet before the school grounds or a school crossing, and no more than 500 feet before.
Work zones: a WORK ZONE plaque may be installed above a Speed Limit sign in a temporary traffic control zone.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2B.21 and 7B.05, read November 4, 2026.
Keep your speedometer, tires and brakes ready
The Works® at Ford of Peoria includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check.
Schedule service online and see our service specials first. Ford of Peoria is at 2211 W. Pioneer Pkwy. in Peoria. Get directions.
Ford of Peoria service hours
| Days | Hours |
|---|---|
| Mon-Fri | 7 a.m.-5:30 p.m. |
| Sat | 8 a.m.-noon |
| Sun | closed |
From Ford of Peoria's website, November 4, 2026. Holiday hours can differ.
Speed limit sign FAQ
Who decides the number on a speed limit sign?
The MUTCD says maximum speed limits are set either by state law for a class of road, such as freeways or city streets, or as speed zones based on engineering studies. The Speed Limit sign displays the limit established by law, ordinance or regulation, or adopted by the authorized agency based on an engineering study.
Why are speed limits always in multiples of 5?
The MUTCD requires the speed limits displayed on Speed Limit signs to be in multiples of 5 mph. Advisory speeds on yellow warning plaques are multiples of 5 mph too.
Where are speed limit signs posted?
Where posting is required by law, at the points where one speed limit changes to another, and at the downstream end of a zone showing the next limit. The MUTCD also calls for extra signs beyond interchanges and major intersections, and statutory limit signs at entrances to the state.
Is the yellow speed plaque under a curve sign the speed limit?
No. That is an Advisory Speed (W13-1P) plaque. It supplements an advance warning sign, to warn of an advisory speed for a roadway condition such as a curve. The MUTCD says a Speed Limit sign should not be used for that purpose.
What does a Reduced Speed Limit Ahead sign mean?
It warns that a lower speed zone is coming. The MUTCD says it should be used where the limit drops by more than 10 mph, or where engineering judgment says drivers need advance notice. It must be followed by a Speed Limit sign at the start of the zone, showing the same number.
What is a minimum speed limit sign?
Where engineering judgment determines that slow speeds might impede the normal and reasonable movement of traffic, a Minimum Speed Limit (R2-4P) plaque may be mounted below a Speed Limit sign to show the minimum legal speed. A combined sign showing both the maximum and minimum limits may be used instead.
What does a CITYWIDE or RESIDENTIAL plaque above a speed limit sign mean?
Some jurisdictions post the limit only on streets entering a city, neighborhood or residential area. A CITYWIDE, NEIGHBORHOOD or RESIDENTIAL plaque above the sign and an UNLESS OTHERWISE POSTED plaque below it show that the limit applies to the whole area unless another sign says otherwise.
How far from a school does a school speed limit zone start?
The MUTCD says the reduced school speed limit zone should begin at least 200 feet before the school grounds or a school crossing (farther if the school limit is 30 mph or higher), and no more than 500 feet before them.
What does The Works at Ford of Peoria include?
The Works® at Ford of Peoria includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check.
Book a routine checkup
Book The Works, which includes a brake inspection, tire rotation and pressure check, and battery test, at Ford of Peoria.
Sources
Sign descriptions are from the Federal Highway Administration's Manual on Uniform Traffic Control Devices, 11th Edition with Revision 1 (Revision 1 dated December 2025), read November 4, 2026. This page is a plain-language summary of national standards, not legal advice; state law sets the rules of the road where you drive. Service details, address and hours are from Ford of Peoria's own website, checked the same day. Photo is illustrative.
- Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1 (Sections 1D.05, 2A.05, 2B.01-2B.03, 2B.21-2B.25, 2C.12, 2C.40, 2C.59, 7B.05), Federal Highway Administration, Revision 1 dated December 2025 (PDF updated February 12, 2026), read November 4, 2026
- General service: The Works, Ford of Peoria, November 4, 2026
- Address and service hours (structured data), Ford of Peoria, November 4, 2026