Plans to allow traffic on a 15-mile stretch of the hard shoulder on the M62 in West Yorkshire have gone on display.
Vehicles could use the hard shoulder at peak times between junction 25 for Brighouse and junction 30 for Rothwell.
The hard shoulder between Brighouse and junction 26 at Chain Bar could be used at all times under the plans.
The Highways Agency said changes would reduce congestion, but some groups have expressed fears about the emergency services getting through.
Brian Gregory, chairman of the Association of British Drivers, said: "To remove a vital emergency lane instead of installing extra lanes is a dangerous bodge and can only lead to confusion and an increase in danger."
David Pillsworth, project manager for the Highways Agency, said: "It makes journey times more reliable, it reduces congestion, and it's good for the environment because we're utilising the existing network."
Staff monitoring the motorway on CCTV would be able to close lanes if a problem was spotted or the emergency services needed to get through, he said.
The plans include lay-bys that would be spaced along the road in case of vehicle breakdown.
The work is part of the government's £6bn Managed Motorway investment scheme to improve national roads which is due to start in October 2010.
The plans, which will be on display in Cleckheaton on Friday and Saturday, are based on a similar scheme in operation on the M42 in the West Midlands.
Transport Minister Chris Mole said: "We have been encouraged by results from the hard shoulder running pilot scheme on the M42 near Birmingham which has demonstrated significant reductions in journey times, plus a reduced number of personal injury accidents."
The Highways Agency said plans were also being drawn up to allow drivers on the hard shoulder of the M1 in South Yorkshire between junctions 32 and 35a near Sheffield.