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• Hoofdstukken

  • 1. Long waiting times at traffic lights due to complexity intersection
  • 2. Location and intensities
  • 3. The regime
  • 4. Waiting times diagonal crossing
  • 5. Improvements diagonal bicycle crossing
  • 6. Absolute priority for high-grade buses
  • 7. Accelerated green for stopping buses
  • 8. Absence of separate directional lanes
  • 9. Discussion

• 1. Long waiting times at traffic lights due to complexity intersection

  

  Utrecht, Biltstraat-F.C. Dondersstraat, traffic lights. As a result of the construction of a bus lane this intersection became so complex that in the current situation a bicycle-friendly regime of the traffic lights is very difficult. Diagonal bicycle crossings, absolute priority for high-grade public transport and a railway crossing are all part of the traffic light system, resulting in a halt line 50 metres before the intersection. Even trainee Luuk Misdom could not find a solution.

• 2. Location and intensities

  

  Biltstraat is a major route for both buses and bicycles (approx. 900 bicycles and 85 per morning peak hour). Cyclists riding east from the town centre have to cross the intersection diagonally, since the one-way bike path changes into a two-way bike path on one side of the street at the intersection. Car traffic may only use Biltstraat in a westerly direction, partly on a separate lane, partly mixing with cyclists. The cross-direction is of major importance to cyclists as well. Occasionally a (freight) train uses the tracks.

• 3. The regime

  

  The intersection has a completely traffic-actuated regime, with standard green for cars and bicycles from the east. Buses call in at a distance. High-grade buses have absolute priority and may overrule phase sequences. The regime is particularly unfavourable for cyclists having to cross the intersection diagonally (average waiting time 42 seconds, green chance 10%, maximum waiting time often over 60 seconds). Yet a ‘mere’ 20% of cyclists jump the lights.

• 4. Waiting times diagonal crossing

  

  The relatively long waiting times for cyclists (and motorists) are caused by several interrelated factors. Council trainee Luuk Misdom studied the matter and mentions the following factors:

  - diagonal bicycle crossing;

  - absolute priority for high-grade public transport;

  - stopping behaviour of bus drivers;

  - absence of separate directional lanes;

  - railroad crossing.

• 5. Improvements diagonal bicycle crossing

  

  The diagonal bicycle crossing is a heavy burden for the regime. All other directions need to be red. And due to the length of the crossing a long clearance interval is called for. Misdom suggests dividing the crossing into two parts. An separate bicycle positioning area could be constructed on Snellenlaan, allowing a stopover for cyclists. Average waiting times for the diagonal bicycle crossing would fall by at least 5 seconds. On condition that direction 2 would receive a green light immediately after direction 22. The recommendation was not realised as the available space would not accommodate a bicycle positioning area.

• 6. Absolute priority for high-grade buses

  

  High-grade buses may overrule the structure of the regime. They are always next in line. This causes (extremely) long waiting times for all other traffic participants, even ‘regular’ buses. It has become a credibility issue. Misdom recommends limiting the overrule possibility to two moments in the cycle. This has not been implemented.

• 7. Accelerated green for stopping buses

  

  Buses call in at a distance from the traffic lights, to ensure a favourable light in time. The regime assumes that buses from the town centre always stop at the bus stop. If the bus does not stop or stops only briefly, this is detected by two detector loops immediately in front of the halt line. This leads to accelerated green. Some bus drivers, however, drive too far forward and stop on top of the detector loops when boarding passengers. They receive accelerated green, but this has often changed to red before all passengers are on board. As a result the bus (and other buses waiting behind) have to wait an entire cycle. It is recommended pointing out to bus drivers to stop only at the so-called stopping tile. If necessary extra railings along the platform could prevent the bus from riding too far forward.

• 8. Absence of separate directional lanes

  

  Motor vehicle direction 11 is also a heavy burden for the traffic light regime. There is no opportunity for a separate left-turn regime, making it virtually impossible to combine green for these motor vehicles with other directions. Initially direction 11 received a green light at the same time as the bus lane. After accidents between left-turning cars and buses going straight ahead this partial conflict was deemed unacceptable. With the inevitable result that cycle time increased. 

• 9. Discussion

  

  In order to actually improve the regime adaptations in lay-out appear necessary. Within the limited space it is impossible to meet all demands and wishes. A major gain is feasible by allowing motor vehicles to use a short stretch of bus lane at the east of the intersection. This would create room for a bike path towards the east, making a diagonal crossing unnecessary. Moreover direction 11 need not and could not be regulated separately. This would result in a two-phase regime, whereby all traffic on Biltstraat would profit from high-grade bus arrangements.