How to Read an Illinois Oversize Permit: Field-by-Field Guide

An Illinois oversize or overweight permit is short on its face, but it travels with a separate provisions sheet every driver has to carry: Form OPER 993. IDOT issues the permit through the Illinois Transportation Automated Permit System (ITAP), under authority in 625 ILCS 5/15-301 and the detailed rules in 92 Ill. Adm. Code Part 554.

A few Illinois rules catch drivers out: loads up to 12 feet wide / 13 feet 6 inches high / 200 feet long can run 24/7 (with an extra escort at night), bigger dimensions step down to daylight-only or a 9 a.m.–3 p.m. CST weekday window, Cook County expressways and the Illinois Tollway need separate permission, and holiday bans start at noon the day before. This guide walks through what an Illinois permit holds and the published rule behind each part. IDOT does not publish a sample issued permit PDF, so where a detail depends on your own permit, read the permit and Form OPER 993, and ask the Oversize/Overweight Permit Office.

MI 01

Who issues Illinois oversize permits

Under 625 ILCS 5/15-301, IDOT may issue a special permit for vehicles or loads that exceed legal size or weight on highways under its jurisdiction. Local authorities issue their own permits for roads they maintain. IDOT’s Oversize and Overweight Permits page and IDOT’s Apply page point applicants to Illinois Transportation Automated Permit System (ITAP) for 24/7 online access; most routine permits issue immediately after payment. New users must register.

Form OPER 993 is clear that the permit is effective only where IDOT has jurisdiction. Permission for municipality, township, county, or skyway roads, and for the Illinois Tollway, must come from those authorities before you move. Toll oversize/overweight permission is at Illinois Toll truck permit site or 630-241-6800 ext. 4847 (Form OPER 993; see also 92 Ill. Adm. Code § 554.312 and § 554.313).

Permit types sit in 92 Ill. Adm. Code Subpart B. The everyday ones are a single trip (one-way, valid 5 working days under § 554.201), a round trip (same or like object both ways on the same route, 10 working days under § 554.202), repeated moves of like objects (at least five trips in 30 days under § 554.203), and limited continuous operation permits for 90 days or one year under § 554.204 (construction equipment, manufactured homes, overweight within practical maximums, and related categories). Specialty permits cover highway crossings, grain/ensilage overweight trucks, and construction-zone equipment. Questions go to the Permit Office at 2300 South Dirksen Parkway, Room 117, Springfield, IL 62764 — 800-252-8636 (Illinois area codes) or 217-785-1477 (out of state), DOT.PermitOffice@illinois.gov (Form OPER 993; § 554.103(d)).

MI 02

The top of the permit: type, dates and fees

Start at the top. Find the permit number (shown here only as a placeholder, IL-XXXXXXX; we never show real ones), the permittee, the permit type, and the effective and expiration dates. Then check:

• Validity. Single-trip permits are valid for 5 working days; round-trip permits for 10 working days and one round trip (§ 554.201, § 554.202). Limited continuous operation runs 90 days or one year as shown on the permit (§ 554.204; 625 ILCS 5/15-302).
• Extensions and revisions. Single-trip, round-trip, and repeated-like-object permits can be extended once for 5 working days if you notify IDOT before the original expires and show good cause (§ 554.210). Only the Permit Office may revise a permit, and only one revision is issued; some fields (permittee name, load description, origin/first route in most cases) cannot be changed (§ 554.211).
• Fees. § 554.906 says fees follow 625 ILCS 5/15-302 through 15-313. For legal-weight overdimension loads other than house trailers, § 15-305 and IDOT Table 1 – Overdimension Fee Categories (PDF) (rev. 1/16/2024) set single-trip brackets by size and distance — for example, up to 10 feet wide / 14 feet 6 inches high / 70 feet long is $12 / $15 / $18 / $21 for the 0–90 / 91–180 / 181–270 / over-270 mile bands. Larger size bands climb to $30–$60, then $50–$125 for loads over 18 feet wide, over 16 feet high, or over 120 feet long. Overweight-axle and overweight-gross fees are in § 15-306 and § 15-307 (charge the greater of the two, not both). House-trailer / modular / truss fees are in § 15-304. For a superload estimate before you buy, use the ITAP Superload Fee Estimator.
• Police-escort fees. When ISP escorts are required, 625 ILCS 5/15-312 (as amended through P.A. 104-468, effective June 16, 2026) sets $40 per hour per vehicle to IDOT (minimum $80) plus $125 per hour per State Police vehicle to ISP (minimum $500), based on actual escort time. § 554.911 still describes an older per-district processing schedule ($80 / $160 Chicago); follow the current statute and what ITAP quotes on your invoice, and ask the Permit Office if they differ.
• Insurance. Owners/operators of escort vehicles, or of vehicles with loads over 10 feet wide, 13 feet 6 inches high, or 110 feet long, or overweight, must carry (or self-insure) at least $500,000 per occurrence combined bodily injury and property damage (Form OPER 993; § 554.108).

Carry it right. Form OPER 993 and § 554.426 say the driver must have the permit in written or electronic form during the move and show it on demand. OPER 993 itself must also be carried in the vehicle. An electronic copy is allowed; IDOT and police are not responsible for damage to a personal device used to display it. Don’t treat the move as started until you’ve read the face of the permit — undertaking the move is evidence you accepted it (Form OPER 993; § 554.106; § 554.209).

MI 03

Permit restrictions and the Form OPER 993 conditions

This is the part most worth slowing down for. Form OPER 993 says its conditions govern the move as if written on the permit. In a conflict, precedence is (1) conditions stated in detail on the short-form permit, (2) Provision “C” special provisions, (3) Provision “B” oversize provisions, then (4) Provision “A” general provisions. Breaking them can void the permit or leave you running unpermitted. The general limitations a driver is most likely to need on the road:

Read your own permit’s restriction lines and any Provision “C” codes word for word. They can add bridge, district, escort, or time conditions for a specific move, and they win over anything general in this guide.

MI 04

Vehicle, load, dimensions and weights

The vehicle and load block should match the truck exactly. 625 ILCS 5/15-301 and § 554.209 put the burden on the applicant to describe the vehicle and load accurately; a mismatch can be a violation of permit or, in some cases, an unpermitted move.

What makes a load oversize in the first place? Form OPER 753 (and 625 ILCS 5/15-102, 15-103, 15-107, 15-111) illustrate the common legal limits: 8 feet 6 inches wide, 13 feet 6 inches high, and Class I/II semitrailer length of 53 feet (other combination lengths vary by highway class). Single axle 20,000 pounds, tandem 34,000 pounds, with gross/bridge limits from the federal bridge formula. Anything above those limits needs the IDOT special permit on state roads.

For overweight, § 554.604 sets “practical maximum weights” that routine permits generally stay within — for example, a 6-or-more-axle tractor-semitrailer up to 120,000 pounds gross (48,000 on the drive tandem / 60,000 on the trailer tandem), or a 5-axle combination up to 100,000 pounds. Heavier or nonstandard configurations are treated as superloads and need more analysis and fees (§ 554.605). Form OPER 993 also sets minimum axle-spacing rules for overweight routine and towed permits (steer-to-drive tandem at least 8 feet 1 inch; spacing before the first trailer axle at least 18 feet 6 inches; sum of all spacings at least 43 feet 6 inches); loads that miss those spacings are processed as superloads.

International shipping containers are non-divisible for permitting only when sealed for international shipment and en route for import/export; the driver must be able to show documentation tying the unique container number to a foreign origin or destination (Form OPER 993).

MI 05

The route section, bridges and clearances

The route section lists each state road and direction in order. Drive that route. § 554.425 says operating on other state-maintained highways is an arrestable offense under § 15-301(j), and further movement is blocked until IDOT gives a return route. Form OPER 993 adds the one-mile contiguous-state-highway relief described above, and points overweight and overheight moves to the Getting Around Illinois Obstructions and Restrictions map for state-line bridge and obstruction checks.

Height is partly on you. Legal height is 13 feet 6 inches, and IDOT does not check vertical clearance when the application says height is legal (Form OPER 993; § 554.429). Practical maximum height for routine permits is about 15 feet (§ 554.508); 16 feet and above needs a route survey by the applicant, and 17 feet and above also needs utility contacts plus a District investigation. Cook County expressway rules and Chicago CBD rules are printed on OPER 993 — loads over 12 feet wide, 13 feet 6 inches high, or 120,000 pounds (or the listed own-powered equivalents) are barred from most Cook County expressways, with listed Interstate exceptions.

Local streets and the Illinois Tollway are outside the IDOT permit. For Chicago city streets (not expressways), OPER 993 lists the City of Chicago Permit Office at 312-744-4699; for Cook County roads outside Chicago, 312-603-1670. Toll permission is separate via Illinois Toll truck permit site.

MI 06

Civilian escorts and Illinois State Police escorts

Form OPER 993 (Provision B) and 92 Ill. Adm. Code § 554.407 set the published size triggers. Lead with what is printed on your permit and on OPER 993; the face of the permit wins if they differ.

§ 554.407 matches the one-escort and most two-escort triggers, but it lists moves over 18 feet high under the two-escort list (plus ISP), while OPER 993 (Rev. 08/07/24) puts over-18-foot height under three civilian escorts plus ISP. OPER 993 also points readers to “Sections 554.1235 and 554.1240” in IDOT’s Permit Office Policy Book for full escort detail — numbering that does not match the published Adm. Code sections above. When those sources disagree, follow the face of your permit and the OPER 993 copy in the cab, and confirm with the Permit Office before you roll.

Civilian escort equipment is in § 554.408: passenger car or light second-division vehicle (not over 8,000 pounds GVW) with clear front and rear vision; driver 18 or older and licensed; roof-mounted rotating or flashing amber lights visible 500 feet in normal sunlight; OVERSIZE LOAD sign; radio contact with the load; roughly 300 feet ahead on two-lane roads or behind on multilane divided highways in rural areas; and a height pole on the lead escort when height exceeds 14 feet 6 inches. One escort per permitted load — convoys need Permit Office authorization and usually an ISP escort. For how escort triggers compare across states, see our guide to pilot car requirements by state.

MI 07

Travel times, Cook County windows and holidays

Authorized times on Form OPER 993 (Rev. 08/07/24) are more specific than the older daylight rules in § 554.422 (last amended 2012). Lead with OPER 993 and your permit; note the Code mismatch below.

Provision “C” on OPER 993 also tightens moves greater than 14 feet 6 inches wide up through 16 feet wide to 9 a.m.–3 p.m., Monday–Friday in Cook, DuPage, Lake, Kane, Madison, McHenry, Monroe, St. Clair, and Will Counties. § 554.422 still describes a simpler 12′ / 13′6″ / 115′ daylight pattern and does not list the 24/7-with-night-escort band that OPER 993 now uses for loads up to 12′ / 13′6″ / 200′. Follow OPER 993 and the face of your permit; ask the Permit Office if your Provision codes and the Code text disagree.

Holidays. Oversize permit loads are further restricted on New Year’s Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day, beginning at noon the day preceding the holiday or holiday weekend (Form OPER 993; § 554.422(a)(1)). Dated windows from IDOT Permit Office 2025–2026 Holiday Office Closings / Permit Travel Restrictions (PDF) (checked November 7, 2026) apply to all permit movements with at least one dimension greater than legal, except over-width-only implements of husbandry:

IDOT’s published holiday list covers 2025 and 2026. Check ITAP announcements for a 2027 schedule before a New Year’s 2026–27 or later move. For how curfews and holiday bans read across states, see our guide to checking curfews and travel restrictions on an oversize permit.

MI 08

Signs, flags and lights

Form OPER 993 and § 554.417–419 set the equipment, unless the permit says otherwise:

• Flags. Clean bright red flags, at least 18 inches square, with no advertising, on the extremities of all oversize vehicles, combinations, or loads, and on all protruding objects (Form OPER 993; § 554.417).
• OVERSIZE LOAD signs. Mandatory on the front and rear when the load is over 10 feet wide, over 14 feet 6 inches high, or over 75 feet long. § 554.419 describes approximately 12-inch black letters (2-inch stroke) on a yellow sign about 7 feet by 18 inches (minimum letter height 10 inches / 1.41-inch stroke). Escort signs may be reduced to 8-inch letters on a 5-foot by 12-inch panel.
• Amber lights. Every OS/OW permit move must display an operable oscillating, rotating, or flashing amber light(s), visible from front and rear; if the load blocks the rear view, add a light at the rear of the load (Form OPER 993; § 554.418). Objects over 80 feet long need two amber lights — one over the cab and one within 10 feet of the rear of the object, mounted as high as practicable.

MI 09

Emergency moves and where to get help

92 Ill. Adm. Code Subpart H covers emergencies and related special moves (mobile-home emergencies, railroad derailments, radioactive and highly hazardous materials, livestock, disabled vehicles). Emergency and other special movements may be authorized for travel at any time when the need is justified (§ 554.422(a)(3)). District Offices may also authorize excessive size/weight movement under emergency conditions (§ 554.305).

For anything else, start with Illinois Transportation Automated Permit System (ITAP) or call the Permit Office: 800-252-8636 (Illinois area codes) or 217-785-1477 (out of state), DOT.PermitOffice@illinois.gov. Mail and walk-ins go to 2300 South Dirksen Parkway, Room 117, Springfield, IL 62764. For ISP escorts, call 217-782-6527 at least 24 working hours ahead. For Tollway travel, use Illinois Toll truck permit site. For Chicago city streets, 312-744-4699; for Cook County roads outside Chicago, 312-603-1670 (Form OPER 993).

MI 10

A pre-trip checklist, and where JaloPermit fits

Before departure on an Illinois permit, confirm:

1. The IDOT permit and a current Form OPER 993 are in the cab (paper or a clearly legible electronic copy), and you have read every Provision code on the face of the permit.
2. Every dimension, axle weight and spacing, plate and description on the permit matches the loaded truck, and any revision or extension is attached.
3. You will drive the printed state route only (plus the one-mile relief if you need it), you have local permission for any non-state roads, and you have Tollway permission if you use the Tollway.
4. Escorts match OPER 993 and the permit: civilian count, amber roof lights, OVERSIZE LOAD signs, radios, and a height pole when height is over 14 feet 6 inches; ISP booked 24 working hours ahead when required.
5. The move fits the time rules on OPER 993 (including any 9 a.m.–3 p.m. county or statewide window) and is outside the holiday windows (including Thanksgiving 2026 from noon Nov. 25 to sunrise Nov. 27).
6. Weather is clear of snow/ice and the house-trailer wind limit if it applies, Cook County expressway and Chicago CBD rules are checked, and you have read each restriction line on the permit and on OPER 993.

JaloPermit can speed up the reading part. Drop an already-issued, text-based permit PDF into the permit decoder on the JaloPermit homepage and it lays out the route, escorts, time limits, dimensions and limits on one route card, with weigh stations, truck stops and low-bridge alerts. Then compare it with the original. For the state rules at a glance, see the Illinois page in the JaloPermit Atlas. For a general walk-through of any state’s permit, see how to read an oversize load permit, and for escort rules side by side, see pilot car requirements by state. Our Ohio, Pennsylvania, Wyoming, North Dakota, Kansas, Texas, Michigan, Minnesota, Oklahoma, Louisiana, New Mexico and Arkansas permit guides cover those states the same way, and if your trip crosses state lines, read multi-state oversize permit trips.

JaloPermit, which publishes this guide, is a reading aid for issued permit PDFs. It is not a permit-filing service and it does not plan routes or provide navigation. The issued permit always wins.

JaloPermit reads text-based PDFs only, not scans or photos. Guests get three free decodes a day with no account and no card. Logged-in users get 10 free decodes a day. After those free decodes, each one is $3.50. There is no subscription.

Questions about how JaloPermit reads a permit? Email support@jalopermit.org.

MI 11

FAQs