I was considering the question I fielded at the Livable Streets Talk last night and came across this excerpt from the NCHRP 562 report that is worth citing in the future.
Distance to Nearest Traffic Signal. The current(pre-2006) MUTCD includes a provision that a signal shall not be considered at locations within 300 ft (91 m) of another signal. This is believed to be based on the distance a pedestrian will walk in order to cross the major street. The researchers did not identify data that support this distance or other distances of how far beyond the desired path a pedestrian would be willing to walk. The USDOT’s 1995 Nationwide Personal Transportation Survey did find that most pedestrian trips (73 percent) are 0.5 mi (0.8 km) or less.With most trips being about 2,600 ft (792 m), pedestrians might not be willing to increase their trip length by more than 10 percent in order to walk to a different crossing location. As part of the on-street pedestrian surveys documented in Appendix K, those interviewed were asked “if this crossing was not here, would you walk to the next intersection (point to intersection of interest)?”For three of the sites, only about 25 percent of the respondents would walk to a signalized intersection at 550, 950, or 1,000 ft (168, 290, or 305 m). For the site with a signalized intersection about 200 ft (61 m) from the crossing, about 50 percent of those interviewed would walk to that crossing. The remaining site where this question was appropriate did not follow similar findings. A much higher percentage indicated that they would be willing to walk to another crossing. Over 65 percent of the respondents indicated that they would walk 600 ft (183 m) to cross at a signalized crossing. The number of individuals willing to walk such a distance was influenced by the number of lanes at the site (six lanes), speed and volume of traffic (high), and existing treatment (marked crosswalk only). Several of the respondents selected “yes” to the question and then commented that they walk to the nearby crossing “most of the time” or “sometimes” depending on the weather or other factors.
A future research effort should consider the same question for people on bicycles. Presumably, the speed of a cyclists expands the distance somewhat, but behavior seems largely sensitive to perceived risk.