Comments on the Sylvan Bridge Redesign

A BFOC reader, Doug Taylor, provides the following comments on the Sylvan Bridge redesign and the problems that should be mitigated:

I recently attended the open house for the planned Sylvan Ave. bridge over the Trinity River.  It was held at the West Dallas multipurpose center on 10/7/10.  Construction is planned to start in the summer of 2011 and expected to last about 18 months.  Here are some of my observations and comments.

The proposed bridge over the Trinity will be 6 lanes wide with a shared motor vehicle/bicycle lane on the outside in both directions.  Pedestrians will have a 6 ft wide walkway on both sides.  Access to Crow Park will be via a ramp on the northwest side of the bridge that curves out to the northwest and turns under the bridge to give access to the park and boat ramp.  No access will be provided to park areas on the south side of the bridge.

The bridge will be 60 ft. high requiring a 6% grade coming up from both sides.  The ramp to the park area will have a 5% grade.  No provision will be made to get northbound pedestrian or bicycle traffic across 6 lanes of traffic to the ramp.  Motor vehicle traffic speeds can be expected to be comparable to the Westmoreland and Hampton bridges with speeds of 40-50 mph.  The crossing will be over the north side of the crest of the bridge, which means that northbound traffic may not see crossing pedestrians or cyclists until the last minute and vice versa.

The plans for widening Sylvan at the choke point under the Southern Pacific railroad bridge in West Dallas were not addressed at this meeting, however the projection is that current daily traffic of around 8000 cars per day will rise to 20,000 cars per day with this wider bridge.  That traffic will be bottlenecked anywhere the number of lanes is reduced or sharp turns are introduced, so traffic will be impeded under this bridge as well.  Furthermore, due to the lane narrowing and reduced visibility at this location, this is a hazard point for cyclists and pedestrians.

Potential issues:

1.  High speed motor vehicle traffic in the shared outside lanes is threatening to bicyclists and hazardous. This will discourage cyclists from using the bridge or encourage them to move to the pedestrian walkways.
2.  The steep ramp angles will discourage cyclist traffic in particular families or children riding to the park.
3.  Crossing 6 lanes of traffic as a cyclist or pedestrian is very dangerous unless protected by a crossing light or by an underpass. Crossing 3 lanes of traffic to get to a left turn lane in a bicycle is very hazardous, in particular when the cyclist will not be able to see traffic approaching from the rear until it crests the bridge.
4.  Residents of West Dallas will be tempted to ride in the protected pedestrian sidewalk which is only 6ft wide.  This can be hazardous to both pedestrians and cyclists.

Potential solutions:

1.  Create bicycle lanes separated from the motor vehicle traffic.  If the lanes are actually built so that they run under the roadway, the steep ramp can be shortened and a protected underpass can be installed to allow pedestrian/bicycle traffic to get to the park.  There could be a transition around where the bridge crosses the levees.
2.  Create an underpass from the proposed shared bicycle lanes and pedestrian walkways to allow northbound pedestrian and bicycle traffic to cross under the roadway.  This protects both pedestrians and bicyclists from high speed motor vehicle traffic.
3.  Create an isolated two way bicycle lane on the west side of the bridge.  This would require routing northbound bicycle traffic across the approach roads on both sides, probably at the intersections at Irving Blvd. and Sylvan, as well as Morris St. on the West Dallas side.  Separate the lane from the motor vehicle traffic with a barrier.  Separate the lane from the pedestrian traffic with a barrier.

Obviously if Dallas is serious about creating a viable plan for cycling as well as non-automotive access to Trinity River parks, the bridge plan should be modified.  While the primary function of this bridge is to move a larger volume of motor vehicle traffic at higher speeds across the Trinity, the secondary function of providing safe access to the park areas should not be ignored.


One comment

  1. Monte Anderson · ·

    It is obvious that the City of Dallas is still only concerned with the car. Why waste the money on bike and walk lanes that will not get used? The people of Dallas should pay close attention when plans for any road are being created. By the time the plans are done they take a life of their own and it is very hard to stop them. Attend roadway meetings early in the process.

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