MARIN COUNTY (CBS SF) – Marin County sheriff’s deputies will start using LIDAR and radar devices in April to monitor the speed of bicycles and mountain bikes in the county’s Open Space District lands.

The speed reduction measures are already in use on the Mill Valley-Sausalito Multiuse Pathway. A serious injury accident between a cyclist and pedestrians in September 2014 demonstrated the need for immediate speed reduction measures, Marin County parks officials said.

The Marin County Open Space District manages 34 open space preserves that include 249 miles of roads and trails within their 16,000 acres.

The Marin County Parks Road and Trail Management Plan that was approved in December 2014 aims to improve visitor experience and safety of hikers, equestrians and mountain bikers alike. There is a mandatory 15 mph speed limit for unpaved roads and trails, and a 5 mph limit when passing and around blind corners.

However, open space rangers have not had an accurate way to measure speed, and uneasiness about safety still exists with some visitors, parks officials said.

A sheriff’s deputy has helped rangers patrol open space preserves for the past 25 years, and a second deputy was added in October. Starting in April, deputies will use radar and more accurate LIDAR—Light Detection and Ranging—devices that measure distance with a laser.

Marin County Parks’ Share the Path initiative has used LIDAR on the Mill Valley-Sausalito Multiuse Pathway since last May.

“Since then, Marin County Parks has seen a decline in user complaints and incidents tied to biker speeds on that path,” Marin County Parks’ interim director Pat O’Brien said in a statement.

Using LIDAR in the open space reserves was a natural and proven development, even though the great majority of bike riders respect safety on open space trails, O’Brien said.

Max Korten, acting assistant director for Marin County Parks, told KPIX 5 that speeding bicyclists would receive warnings for now. It is unclear when tickets would be issued.

Measure A funds for Marin County Parks will pay $4,986 for two LIDAR devices.

“This new measure will augment our current efforts to address violations and hopefully lead to a safer and more enjoyable experience for visitors,” Acting Parks and Open Space superintendent Ari Golan said in a statement.

© Copyright 2016 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.