Climbing lane
Encyclopedia
Climbing lanes are a roadway lane
Lane
A lane is a part of the roadway within a road marked out for use by a single line of vehicles in such a way as to control and guide drivers for the purpose of reducing traffic conflicts. Most public roads have at least two lanes, one for traffic in each direction, separated by Lane markings...

 design typically used on Interstate highways. They allow slower travel for large vehicles, such as large trucks or Semi-trailer truck
Semi-trailer truck
A semi-trailer truck, also known as a semi, tractor-trailer, or articulated truck or articulated lorry, is an articulated vehicle consisting of a towing engine , and a semi-trailer A semi-trailer truck, also known as a semi, tractor-trailer, or (in the United Kingdom and Ireland) articulated truck...

s, up a steep grade. Since heading uphill is difficult for these types of vehicles, they can travel in the climbing lane without slowing traffic behind them.

On major routes, such as motorways in the UK, the climbing lane is also referred to as a crawler lane.. A variation that has become common with newer roads and more recent widening schemes is to add an additional "fast" (passing
Passing lane
A passing lane or overtaking lane is the lane on a multi-lane highway or motorway closest to the center of the road ....

) lane for the stretch which otherwise would have had a crawler lane. This allows underpowered vehicles to remain in the existing "slow" lane without having to purposely pull left into the "slow" lane (which some drivers may not do because of pride or ignorance - particularly tow-car drivers assuming it is a "truck only" lane), or having to try to merge back into faster traffic (possibly still at low speed) when it ends; instead, the more normal requirement to purposely pull out to pass slower vehicles, and back in after doing so or when the lane ends, generally with a smaller speed differential (as they will be rejoining what is already a passing lane), is placed on faster drivers.

An example of a climbing lane is in Telephone Canyon (also known as Evans Pass), southeast of Laramie, Wyoming
Laramie, Wyoming
Laramie is a city in and the county seat of Albany County, Wyoming, United States. The population was 30,816 at the . Located on the Laramie River in southeastern Wyoming, the city is west of Cheyenne, at the junction of Interstate 80 and U.S. Route 287....

. As I-80 climbs through the Laramie Mountains
Laramie Mountains
The Laramie Mountains are a range of moderately high peaks on the eastern edge of the Rocky Mountains in the U.S states of Wyoming and Colorado. The range is the northernmost extension of the line of the ranges along the eastern side of the Rockies, and in particular of the higher peaks of the...

 (via Telephone Canyon/Evans Pass) to the top of the Sherman Summit in the Sherman Mountains, the steep elevation causes difficulty for large or underpowered vehicles. For this reason, a third lane was built to be used as a climbing lane reserved for large trucks.

On normally 2-lane roads without a divider, the climbing lane effectively creates a bi-directional central passing lane of the original uphill running lane. Its subsequent risk of head-on collisions, they are sometimes referred to as "suicide lanes". In some cases to reduce the risk, the road will be signed to prohibit overtaking
Overtaking
Overtaking or passing is the act of one vehicle going past another slower moving vehicle, travelling in the same direction, on a road. The lane used for overtaking another vehicle is almost always a lane further from the road shoulder — that is, to the left in places that drive on the right,...

 when going downhill. Variations on this theme include altered road markings to highlight the climbing lane as being a temporary addition to the normal two (shorter dashed lines similar to those on merge/diverge lanes), or more clearly demarcating the two higher speed lanes (e.g. with markings that prevent uphill fast traffic using the downhill lane to pass slightly slower uphill vehicles themselves passing "crawlers", but still allowing downhill vehicles to overtake using the faster uphill lane if necessary, which has the effect of creating a false "center" line between the two regular lanes)

As truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s and recreational vehicle
Recreational vehicle
Recreational vehicle or RV is, in North America, the usual term for a Motor vehicle or trailer equipped with living space and amenities found in a home.-Features:...

s must use low gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

 to descend slowly, an additional lane may also be built on the downhill side. This prevents the vehicles from overusing their brake
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....

s, which may overheat and cause a runaway vehicle.
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