well, the design intent is for sharrows to be placed in lanes considered too narrow to place bikelanes or where the placement indicates the bikelane should be dropped, also in 'marginally wide' (or is that 'marginally narrow?') lanes and with speeds of less than 35 mph.

i think these defining characteristics are crucial. as cyclists are expected to 'share the lane'.

1)sharrows work well as part of hybrid streetscape design to include vehicularily rideable bikelanes where roadway widths are ample for AASHTO compliant +1 foot buffered bikelanes in urban areas.

2)sharrows should be usable in any width lane as long as they unequivocally indicate a cyclist may use the full lane that is being striped.

2a) they can be effective at directionality and lateral placements. i see them being used to guide bike traffic across multilane, slow speed arterials to position bicyclists out of the right lane (bike or general traffic lane) to position for left turns in a dedicated left turn bike pocket or general turn lane depending on intersection dynamic.



high speed differentials, narrow lanes and sharrows? dubious to ever develop as a considerate accommodation for bicyclists.