NEWTON—A new marking appeared on Old Main Street this week: a bicycle under two chevrons in the roadway’s driving lanes.


Social media posts about the new markings expressed concern — those who do not understand what the markings mean, and, wondering why bicyclists would not instead use the sidewalk on a street that some say sees regular breaking of speed limits by drivers.


Lori Kessler, with the Harvey County Health Department and the Healthy Harvey Coalition, can answer those questions — starting with what those markings are.


They are called “sharrows.”


“The best way to describe it is that is to remind cars that bikes can be using the full lane of traffic, that you need to share the road with the bike,” Kessler said.


She also said Healthy Harvey and Walk Roll Harvey were planning a social media campaign to explain the markings — though they are not totally new to Newton. The first set of sharrows was placed on Boyd Avenue in about 2016.


Local counts and research do not yet show whether sharrows increase bicycle traffic where they are being used. The next bike count, which was delayed this year, will be June 11.


The Federal Highway Administration gave sharrows its official blessing in 2009. The first sharrows arrived in Newton a few years ago, painted on Boyd Avenue when the city redid the street.


Sharrows are designed, Kessler said, both to tell cyclists where to be and to alert drivers that cyclists will be there.


And while the only portion of Newton where riding bicycle on the sidewalk is not allowed is downtown, there is reason to funnel bicycles to the streets and away from sidewalks.


“The reason we do not recommend riding bikes on the sidewalks is pedestrians,” Kessler said. “And there are cars coming out of driveways, allies — they don’t look for bikes on the sidewalk. They look for people walking. ... They are not looking for someone moving at the speed of a bicycle.”


In 2015, civil engineering scholars of the University of Colorado at Denver chose to research the safety of sharrows. Gathering data on more than 2,000 blocks of Chicago in 2000 and 2010, they catalogued where sharrows were painted during this time, where bike lanes were installed or where no cycling infrastructure emerged. Then they layered on statistics about bike commuting and street collisions.


The analysis revealed two issues. The first was that bike lanes were far more effective than sharrows when it came to encouraging more cyclists to a given block and that sharrows showed only slightly higher increases in bike commuting than places where nothing was built.


The number of injuries that occurred per 100 cyclists in a given year decreased the most in areas that installed bike lanes, nearly 42%. The study showed injuries in blocks with sharrows only declined about 20%.


However, sharrows are a less expensive way to create bicycle infrastructure and do not require reconfiguration of — or widening of — a street to create a dedicated bicycle lane.


There are plans for a more sharrow markings on north/south streets in Newton, as suggested by the master plan. Also on the way are street signs for Old Main to go with the sharrow markings.