SAFETY CONSIDERATIONS

HOV FACILITIES AND MANAGED LANES IN HOUSTON Suhag Kansara Ned Levine, PhD

Houston-Galveston Area Council TRB Conference on HOV and Managed Lanes Houston, TX April 18, 2005

Purpose

• Document crashes on HOV lanes • Compare safety of HOV lanes with General

Purpose freeway lanes

• Identify characteristics of HOV crashes

Data sources

• METRO HOV crash data 2001-2004 • DPS freeway crash data 1999-2001

HOV Corridors in Houston Region

HOV Crashes 2001-2004

100 75 50

Central Houston HOV Crashes: 2001-2004 METRO Database

150 125

2001 2002

Year

2003 2004

Crashes by time of day: 2001 45.0% 40.0% 35.0% 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% 12-4AM

HOV Lanes Freeways

4-8AM 8-12PM 12-4PM

Time Period (Four Hrs)

4-8PM 8-12AM

HOV Crashes 2001

50 40 30 20 10 0 IH 10 W HOV Crashes by Freeway: 2001 Metro Database US 290 IH 45 N US 59 N

F reew ay

IH 45 S US 59 S

Crashes on HOV segments

Crashes on Freeway segments

Crash risk: HOV vs. Freeway lanes

200 HOV Crash Risk: 2001 Crashes Per 100 Million VMT

Freeway crashes HOV crashes

150 100 50 0 IH 10 W US 290 IH 45 N US 59 N

F reew ay

IH 45 S US 59 S

Multiple Crash Locations

Multiple Crash Locations – large scale

Hot-spot locations

HOV lanes merging to freeway lanes

Hot-spot locations

Direct access ramps merging with HOV lanes from park and ride lots

Junction related HOV crashes

Hot-spot locations

Design compromises in geometrical structure of HOV lane – shoulder width

Contributing factors • Single vehicle crashes

HOV facility Freeway facility 30% 24%

• Speeding

HOV facility Freeway facility 53% 56%

• Following too close

HOV facility Freeway facility 5% 3%

Tentative conclusions • HOV lanes are safe • Design compromises can increase crash risk • Trade-off safety between barrier facilities vs.

diamond lanes

Future research • Compare barrier facilities with diamond lanes • Who is involved in the crashes – Disproportionate number of males – Disproportionate number of persons in their

30’s and 40’s

• Do certain groups have more difficulty with

barrier facility?

For more information, see: http://www.h-gac.com/safety

Thank You