Climate-friendly bus priority measures and safe mobility  

Increasing public transport use is a key aim in lowering transport emissions.  To encourage people to get out of their cars and onto buses, transport planners in many cities have developed public transport improvement programs, that often include bus priority measures.  In most cases this means reallocating road-space (traffic lanes and parking) for priority use by buses (bus lanes), or special classes of other vehicles (e.g. transit or high occupancy vehicle lanes). 

Generally, buses and other public transport trips have been shown to be one of the safest way to travel within a city or town.  This is particularly the case in many low and middle-income countries (LMIC).  In these countries public transport is being promoted to address the higher crash risks associated with long walking trips and using private travel, especially powered 2 and 3- wheelers.  

Wellington bus lanes

Bus priority lanes

Bus priority lanes offer two key benefits that are sought after by all road users:

  1. Increased journey reliability
  2. Preferential faster travel. 

However, the latter can create safety issues when bus priority lanes are provided on congested arterial roads, which results in relatively fast-moving buses travelling next to slow-moving or stationary queued private motor-vehicles.  While this increases the attractiveness of this mode, the differential speed can result in an increased crash risk, especially where there are a lot of priority-controlled sideroads and accesses. 

As specified in the New Zealand Crash Estimation Compendium, bus lanes can increase crashes by 25%, and when shared with high occupancy vehicles by 60%.  Read more (page 61):

In developed countries, bus travel often extends the length of the walking trip at each end of journey, in some cases by a lot, compared to trips by private vehicles.  At the origin or the destination, patrons typically need to cross a busy arterial road and may cross other busy roads to walk between the bus stop and their ultimate destination.  While busy bus stops, including central city bus-stops, have controlled crossings, the majority do not. This means some, often many, people (including elderly) have to cross a very busy arterial road as part of their journey to/from the bus at locations with little or no crossing aids.  As bus patronage increases, the incidence of passengers involved in a collision as part of their walking journey to/from a bus can be expected to increase unless infrastructure and speed management measures are put in place to protect these vulnerable road users.

When bus lanes replace kerbside parking, the pedestrian crossing distance is increased by the width of the additional lanes.  Without suitable crossing facilities this can further increase the risk to pedestrians.  The iRAP crash risk tools show that adding two additional lanes to two lane road more than doubles the risk of a pedestrian crash.

bus stop auckland

What takes priority: climate change or road safety? 

So should we be building bus lanes and increasing bus usage on arterial roads, given the impact it potentially has on crash risk in our cities and towns. What takes priority: climate change or road safety? 

Well, it has to be climate change, but not at the expense of road safety.  Installing bus lanes is a key method of increasing the attractiveness of travel by public transport.  However, without safe pedestrian infrastructure and appropriate speed environments, the widespread rollout of bus lanes may unintentionally increase the crash risk for pedestrians (and other users) on existing and new bus lanes, at bus stops and routes to bus stops.  The climate change and road safety objectives need to work together. 

This requires:

  1. Building better pedestrian crossing facilities
  2. Looking at potentially lowering speeds of buses across high-risk sections of the bus lane network
  3. Managing vehicle speeds near bus stops on other parts of the arterial road network.

These all align with the overall objectives of safe mobility.        

The Australian Road Safety Conference being held in Christchurch, NZ (28-30 September), will explore the link between climate change and road safety, and the transition that is necessary to achieve goals in both areas.  We hope to see you there!


This is the third blog in Shane’s “Road Safety + Climate Change” series. Read the other blogs in this series:

Achieving Vision Zero while saving the planet

Safer vehicles, safer people and climate change