Designers may occasionally be constrained with respect to the lane arrangements, geometry, or design vehicle that can be accommodated. Mitigation efforts may include placing roadside objects (lights, sign poles, signals, etc.) farther from the edge of pavement so large vehicles do not collide with them. The use of mountable or painted end treatments on raised barriers provides more room for encroachments.

Designers may occasionally be constrained with respect to the lane arrangements, geometry, or design vehicle that can be accommodated. Mitigation efforts may include placing roadside objects (lights, sign poles, signals, etc.) farther from the edge of pavement so large vehicles do not collide with them. The use of mountable or painted end treatments on raised barriers provides more room for encroachments.

Where desired turning lane arrangements cannot be developed, different traffic-control schemes may be used, including turn prohibitions, special signal phasing, or other measures. Whatever design and operating scheme is developed, the designer should verify that adequate intersection sight distance has been provided by the geometry and roadside design features.

From A Guide for Achieving Flexibility in Highway Design, 2004, by the American Association of State Highway and Transportation Officials, Washington, D.C. Used by permission. AASHTO publications may be purchased from that organization's bookstore at 1-800-231-3475 or online at http://bookstore.transportation.org.

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