Out of town bypasses are roads that avoid built-up areas such as towns, cities, or commercial/business districts. Typically designed for higher speed limits, bypasses are intended to allow travelers, including trucks, to continue at highway speeds and reduce through traffic congestion within towns and cities. Bypasses may incorporate more than one town, looping around rural communities1.
Expected Beneficial Outcomes (Rated)
Increased pedestrian and cyclist safety
Other Potential Beneficial Outcomes
Improved quality of life
Improved sense of community
Evidence of Effectiveness
Out of town bypasses have been shown to decrease traffic injuries on both main roads through town and on bypass roads1, 3, 4. Out of town bypasses appear to reduce truck traffic on main roads through town5, 6. A New Zealand-based study suggests out of town bypasses may also increase cycling and cyclist safety when cycleways or bike paths are included6. Bypasses can reduce social disturbances such as noise levels7, 8, support community cohesion, and improve overall quality of life in towns8, and reduce particulate matter pollutants near the bypassed road9.
Bypasses are often located in less populated areas, since changing traffic flow may increase air pollution4 and noise levels, and decrease community cohesion near the bypass2, 4. In some instances, out of town bypasses may shift crash locations, modestly reducing effects on overall crash rates10.
Experts suggest that bypass routes can be effectively incorporated into previously established networks by transit planners7.
Impact on Disparities
Bypass roads are found in urban, rural, and suburban areas throughout the US, although design and operational practices vary11.
CUTR-Bypass - Center for Urban Transportation Research (CUTR). What to expect when you’re expecting a bypass: Webinar and bypass basics brochure. Tampa, FL: Center for Urban Transportation Research (CUTR), University of South Florida (USF); 2014.
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1 Cena 2011 - Cena LG, Keren N, Li W, et al. A Bayesian assessment of the effect of highway bypasses in Iowa on crashes and crash rate. Journal of Safety Research. 2011;42(4):241–52.
2 Egan 2003* - Egan M, Petticrew M, Ogilvie D, Hamilton V. New roads and human health: A systematic review. American Journal of Public Health. 2003;93(9):1463-71.
3 Elvik 2001* - Elvik R, Amundsen FH, Hofset F. Road safety effects of bypasses. Transportation Research Record: Journal of the Transportation Research Board. 2001;1758(01):13–20.
4 Thomson 2008 - Thomson H, Jepson R, Hurley F, Douglas M. Assessing the unintended health impacts of road transport policies and interventions: Translating research evidence for use in policy and practice. BMC Public Health. 2008;8:339.
5 Mills 2011* - Mills J, Fricker J. Integrated analysis of economic impacts of bypasses on communities: Panel data analysis and case study interviews. Transportation Research Record: Journal of the Transportation Research Board. 2011;2242:114-121.
6 Orr 2012* - Orr J. The Ruby Bay bypass – The project that pushed the boundaries. Proceedings of the Institution of Civil Engineers - Municipal Engineer. 2012;165(4):215-218.
7 Gaffney 2017 - Gaffney JL, Bunker JM, Dawes LA. An investigation into the need for highway bypass development. Australasian Transport Research Forum; 2017.
8 Ramis 2003* - Ramis J, Alba J, Garcia D, Herna F. Noise effects of reducing traffic flow through a Spanish city. Applied Acoustics. 2003;64(3):343-64.
9 Burr 2004 - Burr ML, Karani G, Davies B, Holmes BA, Williams KL. Effects on respiratory health of a reduction in air pollution from vehicle exhaust emissions. Occupational & Environmental Medicine. 2004;61(3):212-8.
10 Elias 2011* - Elias W, Shiftan Y. The safety impact of land use changes resulting from bypass road constructions. Journal of Transport Geography. 2011;19(6):1120–9.
11 US DOT-FHWA - US Department of Transportation (US DOT). Federal Highway Administration (FHWA).
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