Saddlemounts allow multiple trucks and tractors to be combined safely, saving commercial operators time and money. Certain types of saddlemount combinations can be operated in Ontario with a Special Vehicle Configuration permit under specific conditions.

Four-vehicle saddlemounts

Four-vehicle saddlemount combinations are composed of tractors, trucks or both, with each vehicle facing forward and its wheels in contact with the highway. The second and any subsequent vehicle is connected to the vehicle ahead by means of a saddlemount device which performs as a fifth wheel assembly and is not a forward extended saddlemount device.

A 4-vehicle saddlemount combination

A 4-vehicle saddlemount combination

Three-vehicle forward extended saddlemounts

Three-vehicle forward extended saddlemount combinations are composed of three tractors, trucks or both, with each vehicle facing forward and its wheels in contact with the highway. The second and any subsequent vehicle is connected by a forward extended Z-boom saddlemount device that has an upper coupler plate with a kingpin that acts as a fifth wheel assembly.

A 3-vehicle forward extended saddlemount combination

A 3-vehicle forward extended saddlemount combination

Get a permit

To apply for a special vehicle configuration permit to operate extended saddlemount configurations, contact the Ministry of Transportation’s Carrier Program Development Office.

Email: VWD.Monitoring@ontario.ca

By mail:

Ministry of Transportation
Permit Office
301 St. Paul Street, 3rd Floor
St. Catharines, Ontario
L2R 7R4

Tel: 416-246-7166
Toll-free: 1-800-387-7736
Fax: 905-704-2545

Program conditions


  • Industry has expressed interest in operating 4-vehicle saddlemount combinations since the U.S. government increased the allowable overall length of saddlemount configurations from 25 metres (82 feet) to 29.6 metres (97.1 feet). The longer length provides greater opportunity to combine 4 truck-tractor and/or incomplete truck chassis, whereby the 25 metre limit often restricts combinations to 3 vehicles in length.
  • Previous reviews of collision statistics and dynamic performance analysis showed that 4-vehicle saddlemount configurations were inferior in performance and safety to that of the 3-vehicle configuration.
  • In 2006, Quebec approved 4-vehicle saddlemount and 3-vehicle extended saddlemount operations under special permit, limiting operations to 90 km/h, off-peak travel, only on weekdays and only under good weather conditions.
  • In 2012, industry renewed interest in allowing the operation of 4-vehicle saddlemounts in Ontario. Industry also expressed interest in operating 3-vehicle forward extended saddlemounts, providing dynamic performance analysis for these configuration types.
  • In October 2016, further study was conducted around the dynamic performance of 4-vehicle combinations whereby it was determined that these configurations could safely operate while under certain operating conditions similar to those in Quebec.
  • By way of special vehicle configuration (SVC) permits, the Ministry of Transportation (MTO) will allow the operation of 4-vehicle saddlemount combinations and 3-vehicle forward extended saddlemounts combinations, subject to the conditions outlined below.

General conditions

  • Carriers operating extended saddlemount combinations must follow all conditions.
  • Permits will be issued to carriers under the SVC Program on a fleet basis. The permit (original or a copy) must accompany the combination and be produced on demand to a police officer or enforcement officer appointed to carry out the provisions of the Highway Traffic Act (HTA).
  • Permits may be transferred between qualifying vehicles operated by the same permit holder under the same Commercial Vehicle Operator’s Registration (CVOR)/National Safety Code (NSC) registration number specified on the permit.
  • The permit cannot be combined with any other permit for width, height, length or weight.

Carrier qualifications

  • Carrier will maintain a minimum $5 million public liability insurance coverage.
  • Carrier has at least 5 years of prior saddlemount (drive-away) experience.
  • Carriers may be required to provide documentation with the permit application to support their qualifications.
  • Carriers must identify one or more personnel as a primary contact for the program and notify MTO of any changes immediately. Contact information and updates will include name, title, address, telephone, cell and email address.

Driver qualifications

  • Drivers must have a valid Class A driver's licence with Z (air brake) endorsement, or equivalent from another jurisdiction.
  • The carrier must provide and document appropriate training and orientation to drivers on the safe operation of the extended saddlemount combinations.
  • As part of the monthly reporting of operations, the record of each trip will include the name of the driver. Only trips completed while operating as an extended saddlemounts must be reported.
  • Driver must have minimum of 5 years provable tractor-trailer, tractor double-trailer, or saddlemount (drive-away) driving experience.

Areas of operation

  • Carriers are approved to operate on a Primary Extended Saddlemount Network composed of all 400-series highways and the Queen Elizabeth Way (QEW), including ramps. Content and description of the network is an integral part of the permit and should be carried on-board the extended saddlemount combination.
  • Access and egress from the Primary Extended Saddlemount Network can be made at any entrance/exit ramp whereby travel must be no greater than a radius of 10 km from such ramp.
  • Carriers must inform MTO in advance of the origin/destination (O/D) locations at which they intend to operate the extended saddlemount combinations.
  • MTO locations farther than 10 km in radius from interchanges off the Primary Extended Saddlemount Network will be considered upon application from an interested proponent. In these cases, an engineering assessment (or engineered route assessment) must accompany the application for each MTO location for the entire route from the Primary Network (including highway ramps, all turning roadways, intersections, and entranceways to the MTO location).
  • The engineering assessment should be conducted by an engineering consultant qualified to assess highway design and traffic. Consultant’s qualifications to be reviewed by MTO's Provincial Highways Management (PHM) Division prior to undertaking the assessment. It is expected the consultant will have access to AutoTurn® or equivalent turn simulation software and will use pre-approved input variables.
  • If a portion of the route was previously approved or will be shared with another proponent, applicants may work together through the engineering consultant to defray costs.
  • If the MTO is already approved for another carrier, additional carriers require a release from the party who undertook the previous engineering assessment.
  • If access to the MTO location requires an engineered route assessment and involves travel on a municipal roadway or Highway 407/ETR ramp, written consent is required from a transportation official of the municipality and/or Highway 407/ETR acknowledging they are aware of the engineering assessment and do not object to extended saddlemount travel over the proposed route.
  • In cases of emergency whereby the extended saddlemounts may be taken to a destination other than that identified in the Areas of Operation information should be provided to the Ministry. In such event, the carrier must notify the Ministry as soon as reasonably practicable and provide the reason for the emergency, as well as the details of any new origin/destination locations.
  • The carrier must report all emergency incidents as part of its regular monthly report.

Special equipment requirements

  • The lead tractor must be equipped with a functioning anti-lock braking system (ABS) compliant with Canadian Motor Vehicle Safety Standard 121.
  • Lamps and reflectors (conspicuity) must comply with 49 Code of Federal Regulations (CFR) 393.17.
  • Coupling devices and towing methods must comply with 49 CFR 393.71.

Speed restriction

The extended saddlemount combination must not exceed 90 km/h.

Notification of collisions/Incidents/Infractions

  • The carrier must provide email notification to MTO immediately following any reportable collision. Email addresses are provided to participants.
  • Within 10 business days of any reportable collision (as specified in section 199 of the Highway Traffic Act), the carrier must provide a copy of the accident report as well as the carrier's written explanation of the collision circumstances. Email, fax and mail addresses are provided to participants.
  • Within 10 business days, the carrier must provide notification and a description of any non-reportable incident that disrupts traffic or damages property. Email and fax addresses are provided to participants.
  • The carrier agrees that any information provided may be shared with police.
  • Police and enforcement personnel are requested to notify MTO of any participants’ infractions.

Revocation of permits

  • MTO reserves the right to suspend one or more of the permits, revoke permit privileges, or cancel the program at any time, without advanced notice.
  • Permits may be revoked or suspended for breach of any of the conditions included in this document or for non-compliance with the Highway Traffic Act.
  • MTO reserves the right to withdraw approval or modify conditions related to the permits without advance notice.

Ongoing evaluation process

  • Participants agree to maintain a record of each extended saddlemount combination trip on an MTO-supplied Excel spreadsheet. Each month’s data is to be submitted to MTO electronically within 10 business days of the month’s end to VWD.Monitoring@ontario.ca. MTO will treat all data from individual carriers as confidential, although aggregate results may be reported.
  • Recorded trip information will include time and date of dispatch, origin, destination, route, kilometres travelled, and name of the driver.
  • MTO will also track, monitor and evaluate any comments, issues and concerns raised by the public, municipalities, media, other modes, shippers, etc.

Dimensional limit chart

Vehicle partFeatureDimensional limit
OverallOverall lengthMaximum 29.6 metres
OverallWidthMaximum 2.6 metres
OverallHeightMaximum 4.3 metres
Lead tractor or truckInter-axle spacingMinimum 3.0 metres
Lead tractor or truckWheelbaseNot controlled
Drawn tractors or trucksInter-vehicle-unit distanceMinimum 3.0 metres

Weight limit charts

Front axle maximum is whichever of the three below (a, b or c) is lowest
FeatureWeight limit
a) by manufacturer’s axle rating or default
  1. Gross axle weight rating (GAWR) (if verified) or
  2. If GAWR not verified, the lower of:
    1. 5,000 kg, and
    2. the sum of the maximum tire load ratings
b) by tire width11 kg × combined tire widths in mm
c) by axle unit descriptionSingle axle - 7,700 kg
Other axle maximums are whichever of the three below (a, b or c) is lowest
FeatureWeight limit
a) by manufacturer’s axle rating or default
  1. GAWR (if verified) or
  2. If GAWR not verified, the sum of the maximum tire load ratings
b) by tire width

Front axle (towed vehicle) 11 kg × combined tire widths in millimeters

Not front axle (lead or towed vehicle) 10 kg × combined tire widths in millimeters

c) by axle unit description

Lead tractor or truck and drawn tractors or trucks:

Single axle (Single tires) - 9,000 kg

Single axle (Dual tires) - 10,000 kg

Tandem axle - by axle spread:

  • 1.2 < 1.8 m - 18,000 kg
  • 1.8 m or more (Single tires) - 18,000 kg
  • 1.8 m or more (Dual tires) - 19,100 kg

Tridem axle - by axle spread:

  • 2.4 < 2.7 m - 21,300 kg
  • 2.7 m or more - 22,000 kg
Allowable gross vehicle weight: (lower of i and ii)
  1. actual weight on the front axle plus other axle maximums
  2. 63,500 kg