Maryland Oversize Load Permits, Regulations & Axle Rules

Maryland's standard permitted-load window runs from a half hour after sunrise to a half hour before sunset. Saturday movement stops at noon, no afternoon travel, and Sunday is off entirely. Seven holidays are full travel blackouts: New Year's Day, Good Friday, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day. The blackout windows extend well beyond the calendar date, running from around noon the last business day before through roughly 9:00 AM the first business day after, which puts four-day and five-day holes in the schedule near those dates. Good Friday is listed as a travel-prohibited holiday in the state's limits documentation but does not appear on the current holiday restrictions sheet, so confirm the exact blackout window with the Hauling Permits Unit.

Seven other state holidays (Martin Luther King Day, Presidents Day, Juneteenth, Columbus Day, Election Day, Veterans Day, and American Heritage Day) close the permit office but do not restrict movement.

Maryland layers more time windows on top of the basic daylight rule based on size and location. Any load 14 feet or wider is confined to 9:00 AM to 3:30 PM on any highway in the state, not just specific corridors. Loads over 45 tons (90,000 lbs), 100 feet or longer, or 12 feet or wider face the same 9:00 AM to 3:30 PM window specifically on the Capital Beltway (I-495/I-95) and the Baltimore Beltway (I-695/MD 695). Self-propelled special mobile equipment unable to maintain 40 mph is banned from those beltways during morning rush (7:00 to 9:00 AM) and afternoon rush (4:00 to 6:00 PM). Superloads over 150,000 lbs operate in two windows: 9:00 AM to 3:30 PM for day moves or 8:00 PM to 6:00 AM for night moves.

Maryland Transportation Authority (MdTA) toll facilities run under a separate clock. Permitted loads may only move on MdTA highways between 9:00 AM Monday and noon Friday; the full weekend from Friday noon through Monday 9:00 AM is off-limits on those roads. Loads on Fort McHenry Tunnel (I-95) cannot exceed 14'6" in height or 11 feet in width; Baltimore Harbor Tunnel (I-895) is closed to permit loads entirely except for containerized cargo with a valid permit.

Vehicles exceeding 45 tons (90,000 lbs) are speed-limited to 10 mph under the posted speed limit at all times. No movement is allowed when visibility is limited by atmospheric conditions or when road surfaces are made hazardous by rain, sleet, snow, or ice; a driver caught in deteriorating weather must proceed to a safe pull-off and wait.

Continuous 24/7 travel is available in two circumstances. Qualifying overweight-only special mobile equipment (not oversize, capable of maintaining 45 mph) may operate around the clock under a continuous travel permit. And loads at or under 150,000 lbs GVW, 13 feet wide, 90 feet long, or 14'6" high qualify for 24/7 auto-issued permits, running continuously except on state-observed holidays.

Maryland sets no general rush-hour curfew on permitted loads beyond the beltway restrictions and the statewide 14-foot-wide window above.

Maryland's overhang model matters here. The semitrailer length limit of 48 feet is measured as the trailer body alone (the statutory language has no "including load" qualifier), so rear overhang is a separate check, capped at 6 feet, rather than something that adds to the trailer measurement. Front overhang is capped at 3 feet. Exceeding either requires a permit. Rear overhang beyond 4 feet requires 18-inch red or orange fluorescent flags and, at night, red lights at the extremities.

Several commodities get overhang and length relief beyond those standard limits. Piling, poles, and mill logs are exempt from both length limits and overhang restrictions as long as the commodity itself does not exceed 75 feet. At or under 75 feet they move without a permit; over 75 feet they need an oversize hauling permit, but the exemption eliminates the normal overhang cap. Indivisible loads up to 70 feet overall may also move during daylight hours on a combination vehicle without a permit, and they are exempt from the overhang restrictions. Crew and racing shells, and vehicles carrying nursery stock, are exempt from both length limits and overhang restrictions with no length cap stated. Wooden prefabricated roof trusses carried in an inverted position may extend up to 10 feet to the rear rather than the standard 6-foot cap.

Auto and boat transporters are measured differently: the overhang of the vehicles or boats being carried is not counted in the combination's length measurement. Standard auto/boat transporters are limited to 65 feet overall; stinger-steered auto transporters go up to 80 feet overall.

Construction equipment gets commodity-specific escort treatment: over 12 feet wide when traveling off the interstate system requires one escort, whereas on the interstate that same width does not trigger the escort rule by itself. Equipment with buckets, blades, scoops, or other attachments exceeding 12 feet wide must have those attachments removed and transported separately.

Self-propelled cranes (hydraulic or lattice boom) over 120,000 lbs GVW can obtain permits without requiring a new bridge review for each move, as long as the initial special bridge analysis has been done by the Office of Bridge Development and per-axle weights stay at or under 27,000 lbs with at least five axles. The maximum single axle weight on a self-propelled vehicle is 32,000 lbs.

Containerized cargo to and from the Port of Baltimore qualifies for its own annual permit, with higher weight limits on configured axle combinations (up to 90,000 lbs GVW for 40-foot container configurations), 24-hour travel allowed on certain designated routes, and a separate holiday restriction schedule that differs from the standard permit blackouts.

Steel-rimmed equipment traveling under its own power has a specific roadway protection requirement: between 13 and 20 tons GVW it must move on 2-inch timber mats at least 6 inches wider than the treads; at 20 tons and above, 3-inch mats at least 12 inches wider than the treads.

Maryland calls this tier a Super Load, defined operationally as any load exceeding 150,000 lbs gross vehicle weight, or any load running within the "excessive size" envelope: 16 feet or more in height, 16 feet or more in width, or 100 feet or more in length. Maryland's own regulations use "excessive size" for the dimensional triggers and "excessive weight" for the weight tier (any GVW over 120,000 lbs, a lower threshold carrying its own lead-time and escort rules), but the Super Load designation as used in the permit unit's operational documents specifically means loads over 150,000 lbs with mandatory engineering review.

The tier structure and its triggers:

- Excessive size: any one of height ≥16', width ≥16', or overall length ≥100'. Requires a minimum 2 working days advance application. - Excessive weight: GVW over 120,000 lbs (60 tons) up to 500,000 lbs. Requires minimum 10 business days advance application, plus one private escort. - Massive weight: GVW over 500,000 lbs. Requires minimum 30 business days advance application. - Super Load (over 150,000 lbs GVW): requires a valid engineering structural review before the permit can be issued. The dimensional envelope for this category is capped at 120 feet long, 16 feet wide, and 16 feet high. Both private and Maryland State Police escorts are mandatory.

Engineering review fees run $8 per analyzed structure for standard review. A review involving bridge engineer escort costs $20 per structure on the initial move, and $12 per structure for subsequent identical moves on the same application. A completed review is valid for up to six months, covering repeat identical moves within that period without additional review fees. For GVW between 120,001 and 150,000 lbs, the engineering review may be waived if the vehicle travels only on qualifying roadways and keeps per-axle weights within specific limits (steering axle ≤20,000 lbs, single axles ≤27,000 lbs, tandem axles ≤26,000 lbs per axle, tridem axles ≤21,000 lbs per axle, four-plus axles ≤18,000 lbs per axle, with minimum inner bridge distance of 30 feet).

The application process for Super Load moves requires an engineering review, and once the application is approved, the permittee must activate the permit by re-entering the driver's name and phone number and resubmitting for final approval. Permits are valid for a maximum of five days, with one five-day extension available for $5. Exceptional hauling permits, the heavy-combination category requiring six or more axles with at least 50 feet of front-to-rear centerline axle spacing, may not be refunded under any circumstance.

MDOT SHA permits cover only the state highway system. Moves crossing City of Baltimore streets, county-jurisdiction roads, or MdTA toll facilities require separate authorization from each entity. Permittees must also obtain advance permission from owners of any overhead wires, cables, traffic signals, street lights, or other structures the load may disturb.

Maryland's route survey obligations attach to two distinct triggering conditions, one dimensional and one based on weight.

Any load reaching or exceeding 14'6" in height requires both a pole vehicle and a height clearance route survey certification before a permit will be issued. The pole vehicle, which must precede the load at sufficient distance to warn of overhead obstructions, is the physical enforcement of the route survey on the road. The permit office will not issue the permit until the height clearance certification is on file. Maryland's sources do not specify whether the carrier or the state performs the height survey, but the certification must exist before the permit issues, making it a pre-permit obligation.

On the weight side, any load over 150,000 lbs GVW requires a completed engineering structural review before the permit can issue. The review analyzes every structure the load will cross, and the results bind the route: the load must travel that approved route and may not deviate more than 1 mile off the designated path for rest, fuel, food, or repairs. Engineering review validity runs up to six months; identical repeat moves on the same application during that window do not require a new review.

The carrier is also responsible for pre-move contact with railroad or railway superintendents before crossing at grade, and must obtain written permission from the owner of any wire, cable, traffic sign, signal, street light, tree limb, or other structure expected to be disturbed. These contacts are the carrier's obligation, not the state's.

Excessive weight applications (over 120,000 lbs, up to 500,000 lbs) must be submitted at least 10 business days before the proposed move, giving the permit office time to conduct any necessary surveys, studies, or investigations. Massive weight moves over 500,000 lbs require 30 business days. Excessive size applications need at least 2 working days.

Maryland does not describe a state-performed physical pre-trip route inspection for loads short of the height and weight survey triggers. Below those thresholds the route planning obligation rests with the carrier: all permit moves must use the shortest practical route favoring interstates and state routes to minimize travel on secondary and local roads.

Maryland's police escort thresholds are codified, not discretionary in the main. The Maryland State Police (MSP) provides law enforcement escort, and the requirement kicks in at two hard triggers: any load 16 feet wide or wider, or any load exceeding 75 tons (150,000 lbs) gross vehicle weight. Police escort is in addition to, not instead of, private escort requirements: a 16-foot-wide load still needs its private escorts plus MSP.

Between 65 and 75 tons (130,000 to 150,000 lbs), police escort moves from mandatory to discretionary. The SHA Hauling Permits Unit may require MSP if the load falls in that weight range, if traffic will have to be diverted or stopped, if the move will occupy two or more lanes on a multilane highway or both lanes of a two-lane road, or if circumstances justify it for public safety. That last clause gives the permit office broad discretion for any large or complicated move.

Police escort costs are billed to the permittee based on a schedule maintained by the Hauling Permits Unit, covering MSP vehicle maintenance and use plus the overtime rate of MSP personnel. Carriers should not treat police escort as a fixed fee.

The Maryland Transportation Authority polices MdTA toll facilities (the Bay Bridge, Fort McHenry Tunnel, Baltimore Harbor Tunnel, and others). Moves on those corridors are subject to MdTA's operating schedule (9:00 AM Monday to noon Friday) and the facility-specific size prohibitions described under Travel Restrictions, but the sources do not separately detail MdTA police escort coordination procedures. Contact the relevant facility at least one hour before arrival as required.

On arrangement: police escorts for Super Loads are coordinated through the permit process. Because the engineering review must be completed and the permit issued before the move begins, the MSP escort scheduling is part of that approval cycle. No separate booking pathway is described in the sources for smaller loads that fall into the discretionary zone; the Hauling Permits Unit drives that determination.

Maryland draws a strict line on civilian escort vehicles too. Each private escort vehicle may accompany only one oversize or overweight vehicle at a time. Escorted permit vehicles must maintain at least a 1-mile gap from any other escorted permit vehicle traveling in the same direction; unescorted permit vehicles maintain at least a half-mile gap. If traffic backing up behind a permitted move reaches more than six vehicles (counting any escort), the entire move must pull safely off the road to let traffic pass before continuing.