Corridor Access Improvements

Drivers on I-35 use ramps to access mainlanes and frontage roads. Some of the existing ramps do not meet current design standards and others pose access challenges due to their location. Potential solutions under consideration include:

  • moving ramps
  • modifying ramps
  • adding auxiliary lanes, or extended entrance/exit lanes
  • adding collector-distributor lanes, or intersection bypass lanes

The combination of these modifications will improve mobility and safety along the corridor.

Ramp Modifications

In some areas, like downtown Austin, the entrance and exit ramps do not meet current design standards. They are too short, steep, curved or close together for optimal performance. Some exit ramps end too close to heavily congested intersections, which force drivers to make sudden movements between frontage road lanes after exiting or cause ramp traffic to back up due to frontage road congestion. Mobility35 proposes to modify ramps in these areas to:

  • Better manage traffic flow
  • Maximize operational performance
  • Increase safety

Extended Entrance/Exit Lanes

The Mobility35 program proposes to add extended entrance/exit lanes in several locations along the corridor. Extended entrance and exit ramps allow a lane for drivers to match traveling speeds between mainlanes and frontage roads before merging. These lanes are usually installed within the distance between an on-ramp and an off-ramp. Extended entrance/exit lanes:

  • Make merging safer
  • Reduce disruption in traffic flow from merging traffic
Extended Entrance/Exit Lanes

Intersection Bypass Lanes

An intersection bypass lane is a one-way road next to and separate from the mainlanes that allows entering and exiting traffic to merge without disrupting mainlane traffic. Intersection bypass lanes allow traffic to bypass frontage road traffic signals at cross streets without being on the mainlanes. Although many area drivers are unaware of having used them, intersection bypass lanes are already in place in several locations within the three-county area, including southbound I-35 at Hester's Crossing, northbound I-35 at Parmer Lane and southbound MoPac at Duval Road. Intersection bypass lanes are often used between closely spaced interchanges and are vital to the functionality of Diverging Diamond Intersections, which is another Mobility35 Proposed Concept. Intersection bypass lanes:

  • Keep through-traffic separated from merging traffic to avoid disruptions in traffic flow
  • Promote safer lane changing between mainlanes and frontage roads
  • Allow traffic to bypass frontage road traffic signals at cross streets without being on the mainlanes
Intersection Bypass Lanes