Driving safety guide · Michigan City Ford · Michigan City, IN

HOV Lanes Explained: Diamond Lanes, Signs and Markings

High-occupancy vehicle (HOV) lanes, often called carpool or diamond lanes, are reserved for vehicles carrying a minimum number of people. The federal Manual on Uniform Traffic Control Devices (MUTCD) sets how these lanes are signed and marked. Here is how to read them, in plain language.

Gloved hands reaching for a tire on a shop rack
Illustrative photo
HOVat least 2 persons, or more if signs say (MUTCD)
Diamondused only for HOV lanes (MUTCD)
HOV 2+minimum occupancy shown after HOV (MUTCD)
Broken whitecrossing permitted; solid double white: prohibited (MUTCD)

The short answer

An HOV lane is reserved for vehicles carrying at least the number of people shown on its signs, such as HOV 2+. Carpools, vanpools and buses that meet the minimum qualify. The white diamond on the signs and pavement marks a lane as an HOV lane. Signs also show when the rule is in effect, and the pavement lines show where you may move in or out.

What is an HOV lane?

The MUTCD defines a high-occupancy vehicle (HOV) as a motor vehicle carrying at least two persons, or more than two if the signs for a specific road set a higher minimum, including carpools, vanpools and buses.

An HOV lane is one kind of preferential lane: a lane or set of lanes reserved for the exclusive use of one or more specific types of vehicles, or of vehicles with a specific minimum number of occupants. Other preferential lanes are set aside for buses, taxis or light rail.

The agencies that own and operate HOV lanes decide how they are run and what the minimum occupancy is. For more on choosing and entering lanes safely, see our guide on how to merge onto a highway.

From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 1C.02, 2G.01 and 2G.03, read November 4, 2026.

Types of HOV and preferential lanes

The MUTCD describes three basic layouts:

LayoutWhat it looks like
Barrier-separatedOn a separate alignment, or physically separated from the other lanes by a barrier or median.
Buffer-separatedSeparated from the regular lanes only by a narrow buffer area created with pavement markings.
ContiguousSeparated from the regular lanes only by a lane line.

From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2G.01, read November 4, 2026. The MUTCD adds that a preferential lane may allow continuous access or only access at designated locations, may run in one direction or as a reversible lane, and may operate 24 hours a day, for extended periods, only during peak travel periods, or during special events.

What HOV lane signs mean

HOV lanes use several kinds of regulatory signs. The MUTCD describes them this way:

Sign typeWhat it tells you
Vehicle Occupancy Definition signThe minimum occupancy for the lane, such as 2 OR MORE PERSONS PER VEHICLE, or other vehicles allowed despite fewer occupants.
Preferential Lane Operation signWhich lane is restricted, who may use it (such as HOV 2+ ONLY), and the times and days the rule applies (such as 7 AM - 9 AM, MON-FRI). Full-time lanes show no hours or show 24 HOURS.
Preferential Lane Advance signThat an HOV restriction begins ahead, so drivers who do not qualify can leave the lane in time.
Preferential Lane Ends signWhere the HOV restriction ends. On freeways and expressways, one is required at least 1/2 mile before the end of the lane or restriction.
MOTORCYCLES ALLOWED plaqueMounted below an operation sign where motorcycles may use the HOV lane regardless of how many people are riding.

From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2G.03 through 2G.07, read November 4, 2026. Example legends are from the MUTCD; the actual legend on a road is set by the operating agency.

The diamond and the lines: HOV pavement markings

The MUTCD requires an HOV lane to be marked with a white diamond symbol or the word HOV. The diamond must be at least 2.5 feet wide and 12 feet long. The lines next to the lane tell you whether you may move in or out:

Line between the HOV lane and regular lanesWhat it means
Wide solid double white lineCrossing is prohibited.
Wide solid single white lineCrossing is discouraged.
Wide broken single white lineCrossing is permitted.
Wide dotted single white line (right-side HOV lanes)Crossing is permitted for any vehicle to make a right turn.
White chevrons in a buffer wider than 4 feetRecommended where crossing the buffer is prohibited.

From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 3E.02 and 3E.03 and Table 3E-1, read November 4, 2026.

HOV lanes vs. express lanes

A managed lane is one where strategies such as direction of travel, tolling, pricing, or vehicle type or occupancy rules are set and changed in real time as conditions change. A priced managed lane uses tolling or pricing, usually through electronic toll collection, to manage congestion.

The MUTCD says priced managed lanes next to regular lanes on the same route must be signed EXPRESS or EXPRESS LANE(S). In some, every user pays a toll; in others, HOVs may travel without a toll or at a discount. Regulatory signs show the toll, and where the toll varies, signs display the amount in effect at that moment.

From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 1C.02, 2G.17 and 2G.18, read November 4, 2026.

Tips for using an HOV lane

Read the operation sign before you move over: check the minimum occupancy and the hours and days the restriction applies.

Enter and leave only where the line is broken, where a dotted line allows a right turn, or at designated access points. Do not cross a wide solid double white line.

Watch for Preferential Lane Ends signs, and get ready to merge back into the regular lanes when the HOV lane ends.

Rules for who may use a lane, and penalties for misuse, are set by the operating agency and state law, so follow the posted signs where you drive.

These tips are our own, based on the sign and marking meanings above from the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, read November 4, 2026.

Keep your vehicle ready for the road

The Works® at Michigan City Ford 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. Michigan City Ford is at 3930 Franklin St. in Michigan City. Get directions.

Michigan City Ford service hours

DaysHours
Mon-Fri7:30 a.m.-5:30 p.m.
Sat8 a.m.-3 p.m.
Sunclosed

From Michigan City Ford's website, November 4, 2026. Holiday hours can differ.

HOV lanes FAQ

What does HOV lane mean?

HOV stands for high-occupancy vehicle. The MUTCD defines an HOV as a motor vehicle carrying at least two persons, or more if the signs for that road set a higher minimum, including carpools, vanpools and buses. An HOV lane is a preferential lane reserved for those vehicles.

How many people do you need to use an HOV lane?

It depends on the lane. The occupancy, operation and advance signs for each HOV lane must show its minimum occupancy right after the word HOV, such as HOV 2+ or HOV 3+. The agency that owns and operates the lane decides the requirement.

What does the diamond symbol on a lane mean?

Under the MUTCD, the diamond symbol is used only for high-occupancy vehicle lanes. It appears on HOV lane signs and as a white diamond marking on the pavement. Bus, taxi and bicycle lane signs do not use the diamond.

Can I use an HOV lane outside its posted hours?

Some HOV lanes run full time and others only during posted hours. Operation signs list the days and times the restriction is in effect, and full-time lanes either show no hours or show 24 HOURS. Read the sign for the lane you are in; outside the posted hours, the rules for that lane are set by the operating agency and state law.

Can I cross the lines to get in or out of an HOV lane?

Look at the line. Under the MUTCD, a wide solid double white line marks places where crossing is prohibited, a wide solid single white line marks places where crossing is discouraged, and a wide broken single white line marks places where crossing is permitted.

Are motorcycles allowed in HOV lanes?

Where an agency allows motorcycles in an HOV lane regardless of how many people are riding, the MUTCD provides a MOTORCYCLES ALLOWED plaque mounted below the lane operation sign. Follow the signs for that lane.

What is the difference between an HOV lane and an express lane?

Express lanes are priced managed lanes: some or all vehicles pay a toll, and HOVs may ride free or at a discount. The MUTCD says priced managed lanes next to regular lanes on the same route are signed EXPRESS or EXPRESS LANE(S), and the toll in effect is shown on signs.

What does The Works at Michigan City Ford include?

The Works® at Michigan City Ford 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.

Sources

Sign and marking meanings 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 and the operating agency set the rules for each lane. Service details, address and hours are from Michigan City Ford's own website, checked the same day. Photo is illustrative.

  1. Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1 (Sections 1C.02, 2G.01, 2G.03-2G.07, 2G.17, 2G.18, 3E.02, 3E.03), Federal Highway Administration, Revision 1 dated December 2025 (PDF updated February 12, 2026), read November 4, 2026
  2. General service: The Works, Michigan City Ford, November 4, 2026
  3. Address and service hours (structured data), Michigan City Ford, November 4, 2026