Road Diets Presented by: Cristine Gowland, P.E. LADOTD District 62 March 2, 2016
FHWA s 9 Proven Safety Countermeasures 1. Safety Edge 2. Roundabouts 3. Corridor Access Management 4. Backplates with Retroreflective Borders 5. Longitudinal Rumble Strips and Stripes on 2-Lane Roads
FHWA s 9 Proven Safety Countermeasures (Continued) 6. Enhanced Delineation and Friction for Horizontal Curves 8. Pedestrian Hybrid Beacons 7. Medians and Pedestrian Crossing Islands in Urban and Suburban Areas 9. Road Diets or Roadway Reconfiguration
Published in Nov 2014 Available on the FHWA website: http://safety.fhwa.dot.gov Provides a complete explanation of Road Diets and issues/benefits from such projects FHWA Guide
What is a Road Diet? In general, it involves the removal of a through travel lane and dedicates the space for another use (shoulder, turn lane, bike lane, etc.) The most common adaptation involves converting a 4-lane undivided roadway to a 3-lane roadway with shoulders Changes can often be incorporated into an existing overlay project. Provides both safety and operational (delay reducing) benefits.
What is the Correct Name for the Center Turn Lane on a 3-lane Section? Chicken Lane? Suicide Lane? Two-Way Left Turn Lane or TWLTL?
Benefits of Road Diets Reduces the number of conflict points at an intersection or within a section of roadway (Safety) Reduces vehicle-pedestrian conflicts(safety) Improves sight distance for vehicles on the main road and side streets (safety) Reduces delay of through vehicles (efficiency) Adds shoulders for other uses such as pedestrian paths, bike lanes, parking, transit stops, emergency parking, etc. (efficiency/safety)
Mid-Block (Non-Intersection) Conflicts
Intersection Conflicts
Improved Sight Distance
District 62 Road Diet Example LA 21 in Bogalusa, Washington Parish Location Issues: Significant crash history with 2 fatalities in 2004 and 1 fatality in 2005. 2 of the 3 fatalities involved pedestrians. Limited sight distance for side street traffic Limited right-of-way, so could not address sight distance issues by widening the existing roadway Roadway capacity did not warrant 4 through lanes Local officials were aware that there were issues on this section of roadway Bogalusa
Road Diet Example (Continued) ~8,000 ADT in 2013 Project length: 1.5 miles (from Rosa Pearl Lane to E 2 nd Street) Speed Limit: 35 mph No Traffic Signals
Project Details and Benefits SP 030-03-0019 was accepted in May 2008. Road surface was concrete, and this was ONLY a restriping project 4-lane undivided roadway converted to a 3-lane (one through lane in each direction, a TWLTL, and shoulders) Improved sight distance for side street traffic Average Crash Rate Before Project: 31 crashes per year Average Crash Rate After Project: 12 crashes per year Was this project a success?
Lessons Learned Don t let a striping only contract. Be sure that a new surface is provided, even an ultra thin overlay. While grinding removes a large portion of the striping, the original image remains.
Lessons Learned (Continued) Converting a 4-lane undivided roadway to a 3- lane roadway eliminates the possibility of passing. That doesn t always mean that motorists won t illegally pass in the center turn lane: May need to install special signage May need to add gore striping: US 190 Striping Video May need to construct raised islands
Lessons Learned (Continued) Local officials were aware of existing issues on the state highway, so no outreach was required. If your local office identifies a candidate project, involving local officials will be key to the success of the project. A TWLTL alone should not be considered a pedestrian refuge. Spot placement of islands at strategic locations within the TWLTL can provide a safe point of refuge for pedestrians. Adding gore striping or dedicated left turn lane striping at major side street intersections helps discourage vehicles from accelerating or passing in the TWLTL.
Issues to Consider Before Initiating a Road Diet Capacity. Can 4 thru lanes be reduced to 2 thru lanes without creating congestion? FHWA recommendation of < 20K ADT What does the adjacent roadway network look like? Driveway density. How closely spaced are side streets and driveways? Are any safety issues present? Are there traffic signals on the corridor? Possible modifications. Is it right everywhere? Sometimes the answer is obvious: Yes or No Often needs further study Even if you think the answer is obvious, always do a study to verify benefits, requirements, and possible impacts
Example Review: Are These Locations Good Candidates for a Road Diet?
US 190 Hammond, Tangipahoa Parish ADT: 28,000 vehicles per day 2 signals Driveway density? Length: 1,900 feet 45 mph
LA 38 Kentwood, Tangipahoa Parish ADT: 6,000 vehicles per day 2 signals Driveway density? Length: 4,200 feet (I-55 to US 51) 35 mph
US 11 Slidell, St Tammany Parish ADT: 20,000 vehicles per day 5 Signals Driveway density? Length: 1.5 miles (Hall Street to 3 rd Street) 45 mph
US 190 Denham Springs, Livingston Parish ADT: 20,000 vehicles per day 2 signals Driveway density? Length: 1.7 miles (LA 16 to Amite River Bridge) 45 mph
LA 10 Bogalusa, Washington Parish ADT: 12,000 vehicles per day 2 signals Driveway density? Length: 1300 feet (Cumberland Street to Austin Street) 35 mph
Questions/Discussion