An example of the four to three configuration[/caption]
The city of Austin recently released a report analyzing the 37 "right-sizing" projects undertaken in Austin during the past 15 years. The report focuses on past projects and how they are operating after implementation.
Right-sizing is a technique that changes the number of lanes on a street to improve the street's safety and operations for all users, according to the city's report. The most typical type of right-sizing is when the city reduces a four-lane roadway to a three-lane configuration by removing one travel lane in each direction to create a center turn lane and two outer bicycle lanes.
“With right-sizing, the traffic stream flows more smoothly,” said Randy Machemehl, a civil engineering professor at The University of Texas. “This means we could potentially gain green [light] time.”
Such a gain in green light time results from the removal of split-phase signals, which allow only one direction of traffic to initially operate so left-turning cars can enter the intersection—preventing two-way traffic. However, adding a center turn lane or left turn bay combats this by taking left-turning cars out of the traffic flow, Machemehl said. This simple fix results in safety and mobility benefits, he said, along with more green light time.
The city weighed various factors for determining what right-sizing projects to complete, including safety records. The Austin Transportation Department considered repurposing any roadway with a high rate of crashes. Neighborhood associations can also request right-sizing projects to improve safety on local roads.
“We continue to look for opportunities to improve safety and mobility,” said Laura Dierenfield, an active transportation program manager with the city. “Right-sizing an important tool to improve safety and transportation as a whole.”
Because of these reconfiguration efforts, the Federal Highway Administration reported a 19 percent to 47 percent reduction in overall crashes nationwide where right-sizing projects occurred. But before any road can be reconfigured, the city's Transportation Department must conduct an analysis of intersection operations, motor vehicle volumes, crash histories and safety characteristics, Dierenfield said.
Public outreach is included in the process so city staff can gain input from Austinites who use the streets on a daily basis, she said. Notifications are mailed to property owners and tenants whose property is directly adjacent to the project area. Paper mail and emails are sent to neighborhood associations and other stakeholders as well. This way, projects are not carried out that the public opposes, Dierenfield said.
To ensure these projects are effective, the city conducts before and after studies by measuring traffic volumes, travel times, peak hour operations, motor vehicle speeds and crash histories. According to city data, right-sizing had little to no negative impact on traffic operations after implementation.
However, each road experiences different effects from repurposing. Steck Avenue, for example, reported a very slight increase in westbound travel times but a decrease in travel time going eastbound. The city reports that bicycle traffic—along with pedestrian traffic—doubled, tripled or quadrupled on right-sized roadways. The city reports 5.6 percent of commuters now use their bicycle to get to work, and that percentage is expected to grow.
Cameron Road between 53rd Street and Hwy. 290 is another example of a roadway to be right-sized with positive results, according to the city. Despite speed limits ranging between 30-35 mph, motorists typically traveled upwards of 45 mph. However, since that section of Cameron Road was reconfigured, cars reportedly going faster than 45 mph in a 24-hour period decreased from 175 to 22 and crashes reduced by 29 percent.
Despite the decrease in crashes, initial implementation can be counterintuitive, according to Dierenfield, creating negative perceptions. Once people realize how much safer the roads are, reports show an increase in comfort among pedestrians and bikers when crossing intersections. Motorists also report feeling less stressed when making left turns, according to city survey results.
Right-sizing projects can accommodate the same motor vehicle volumes, avoid increases in travel times, reduce high-risk speeding and reduce total crashes, she said. Also, right-sizing delivers such safety improvements at one-tenth of the price of a standalone project when coordinated with routine maintenance, according to Dierenfield. Those positive outcomes have encouraged ATD staffers to continue pursuing right-sizing projects.