INTERSECTION SAFETY PERFORMANCE AND AUDIT

Andy Loonan

Basak Aldemir-Bektas

Intersection: Welch Avenue & Lincoln Way

About the Intersection

• Signalized intersection

• Located between Campus Town and Iowa State University Campus

• Lincoln Way ~ 20,000 VPD

• Welch ~ 7000 VPD

• very high in pedestrian and bike traffic

Pictures from the Intersection

On Lincoln Way median facing west. Time was 12:00 p.m. on a Monday.

The Lincoln Way roadway is a four-lane facility with left turn lanes at this intersection shown in Figure, which runs east and west. In addition, westbound Lincoln Way has a bump out for a bus stop located just west of Welch Ave.

On Welch Ave. looking south at the intersection. Time was 12:00 p.m. on a Monday.

Pictures from the Intersection

Welch Ave. is a north/south two-lane street with the southbound leg at the intersection has a left turn lane with out protected left turn lane.

Signalization and Vision

• Normal two way phasing with designated turn arrows for both left turn movements on Lincoln Way

• Southbound Welch has a left turn lanes without a designated green arrow and the northbound Welch Ave. does not have any turn lanes.

• Welch Ave. also has a small grade issue as the southbound leg is up hill and the northbound direction is down hill.

• The slope differences could occasionally be problematic in blocking the drives vision of pedestrians.

• Other vision obstructions include pedestrians, traffic signal controllers, light poles, sign poles and other signs on Welch in Campus Town. A photo of the traffic controller is shown in the next Figure.

On Lincoln Way north of the intersection facing west.Time was 12:00 p.m. on a Monday

Pictures from the Intersection

Looking East on Lincoln Way

• the pedestrian crossing and stop bars are not visible, •motorcycle doing a u-turn•northbound driver over the stop bar•many vision obstructions for drivers and peds

Crash Investigation• CMAT & SAVER• 2001-2006; 43 accidents• 80 % of the drivers in 16-34 age range• Only 5% of the crashes were alcohol related• 39 of 43 accidents during 8 AM - 8PM period. • (21 %) the major cause was following the vehicle in front too close. • Other major causes:

– Running a traffic signal– Failing to yield right of way while making left turn– Failing to yield right of way from parked position– Failing to yield right of way to pedestrian– Driving too fast for conditions– Making improper turn– Operating the vehicle in a reckless manner– Using phone or other device while driving– And just not paying attention

Recommendations• Improving the signalization, specifically left turns on Welch Ave. This

would greatly improve the safe passage of left turn traffic during the green arrow, as now the method is to creep out to see if you can make it. The left turn bay is already in existence for the southbound movement and the northbound left turn will not be easily created because space may not be available for the improvement. Parking would be lost if the turn lane was created. This may also add benefit to the intersection as we already identified that the parking in close proximity should be eliminated.

• Warning drivers on Lincoln Way before coming to the intersections with high visibility “pedestrian crossing” signage or “signal ahead” signage or both.

• Improve pavement markings by painting every year with high visibility paint that will guide the pedestrians and will assist in warning drivers of the stop bar. In addition, dashed turn curve markings could be added to keep the turning traffic in the correct location.

• Warning pedestrians to obey the traffic signals by putting signs that get this message across to them.

• Removing some parking spaces that are very close to the intersection. Specifically, on Lincoln Way eastbound and abutting Welch Ave. and the Welch Ave. parking just south of Lincoln Way. This will allow for more sight distance for pedestrians bikers, and motorized vehicles and only involves loosing up to 6 parking spots.

• Making the signal heads larger and brighter to improve visibility and increase awareness. The special 12” lights could be used, these are typically used in high speed locations but the usage here could provide that needed increased visibility

• Continue prohibiting right turns on red but improve the signage. • Eliminate some of the newspaper machines and signal controllers to

improve visibility.

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