New designs for older driver-friendly roads

The Federal Highway Administration recently released a guidebook recommending several ways to design roads with older drivers in mind:

  • Enlarging letters on street signs from 4 inches to 6 inches.

  • Installing more traffic lights so older drivers can better manage turns at busy intersections.

  • Building ''rescue islands'' in the middle of wide streets so older pedestrians don't have to cross in one signal cycle.

As America ages, engineers will have to keep in mind the needs of older drivers. Limitations with vision, flexibility and reaction time influence design in the following areas.

Intersections

The single greatest concern in accommodating older drivers and pedestrians is their ability to safely get through intersections. Some intersection design considerations:

  • To help with difficulties judging the distance and speed of oncoming traffic, intersections with moderate or high traffic volume should be straight and level for more than the minimum stopping sight distance. Vehicles popping over hill crests can surprise anyone.

  • Left turn lanes should ensure that vehicles don't block each other's view of approaching traffic.

  • Older drivers tend to encroach into opposing lanes when making a left turn, so avoid using minimum lane widths at intersections.

  • The angle between intersecting roadways should be 90º. Sharper angles require turning the head farther.

  • Minimize decision-making required at intersections.

  • Locations with high pedestrian volume should include refuge islands.

  • Where appropriate, use roundabouts, which eliminate the two critical crash types at normal intersections, right angle and left turn.

Interchanges

Diminished ability to assess the speed and distance of other cars also causes problems for older drivers entering or exiting a highway. Acceleration/deceleration lanes must be long enough, and exits should be located away from sight-restricted areas.

Road curvature

Use slightly wider lanes on tight radius curves.