safety considerations hov facilities and managed lanes in houston suhag kansara ned levine, phd...

SAFETY CONSIDERATIONS

HOV FACILITIES AND MANAGED LANESIN HOUSTON

Suhag KansaraNed Levine, PhD

Houston-Galveston Area CouncilTRB Conference on HOV and Managed Lanes

Houston, TXApril 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

2001 2002 2003 2004

Year

50

75

100

125

150

HO

V c

ras

he

s

Central Houston HOV Crashes: 2001-2004METRO Database

HOV Crashes 2001-2004

Crashes by time of day: 2001

IH 10 W US 290 IH 45 N US 59 N IH 45 S US 59 S

Freeway

0

10

20

30

40

50

HO

V c

rash

es

HOV Crashes by Freeway: 2001Metro Database

HOV Crashes 2001

Crashes on HOV segments

Crashes on Freeway segments

IH 10 W US 290 IH 45 N US 59 N IH 45 S US 59 S

Freeway

0

50

100

150

200

HO

V c

rash

ris

k

HOV Crash Risk: 2001Crashes Per 100 Million VMT

Freeway crashes

HOV crashes

Crash risk: HOV vs. Freeway lanes

Multiple Crash Locations

Multiple Crash Locations – large scale

Hot-spot locations

HOV lanes merging to freeway lanes

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

Hot-spot locations

Junction related HOV crashes

Design compromises in geometricalstructure of HOV lane – shoulder width

Hot-spot locations

Contributing factors

• Single vehicle crashesHOV facility 30%

Freeway facility 24%

• SpeedingHOV facility 53%Freeway facility56%

• Following too closeHOV facility 5%

Freeway facility 3%

• HOV lanes are safe

• Design compromises can increase crash risk

• Trade-off safety between barrier facilities vs. diamond lanes

Tentative conclusions

• 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?

Future research

For more information, see:

http://www.h-gac.com/safety

Thank You