West LA / 405 Corridor Traffic Improvements
(First study using the Cotner Avenue Alternative)
Abstract of the Study
This initial study sets out the basic transportation problems to be solved for in the West LA 405 corridor and develops a list of construction improvements to establish a first stage Flow Boulevard with Bus Rapid Transit to be utilized as a frontage road to the 405 freeway. The additional vehicular capacity that a Flow Boulevard provides; 1/ allows the 405 freeway to work without failing, 2/ would remove the cut-through traffic from the presently impacted adjacent residential communities and 3/ eliminates the congestion that is brought about by the inadequate 405 ramps to perform commuter distribution and collection to and from Westside destinations (presently some 692,000 person trips per day).
The low cost of establishing the eight miles of Flow Boulevard is estimated to be approximately eighty million dollars total (without busses) and could be implemented with a few years of planning process and a year of construction. This corridor improvement would “prove” the value of Flow Boulevards in Los Angeles to solve congestion, and begin a high density land use transportation corridor while connecting the San Fernando Valley, the Westside and Culver City with Bus Rapid Transit.
Study Beginning The main purposes for the corridor street improvements are a/ to provide additional vehicular capacity off of the 405 itself to make it so the 405 Freeway does not fail (LOS F) due to the excessive crowding on of travel demand, b/ to remove the 405 freeway “spillover” traffic from impacting adjacent residential communities with “cut through” traffic and c/ to provide additional distribution and collection capability for the commuter exchanges of the 405 corridor with the adjacent work centers and communities.
The method is to increase through-put capacity on a few designated commercial streets adjacent to the 405 in order to absorb the excess travel demand that brings LOS F to the 405 and to provide increased turning movement opportunity in the corridor to and from the cross streets that will exchange traffic with the improved north-south streets. Presently there is a lack of turning movement and merging opportunity onto the 405 that backs up traffic getting on and off the Freeway. This improved facility will be a commercial route outside of the residential communities as well as the 405. The newly improved streets will also be the place to add traffic absorbing capacity in the corridor in the future as well.
The improved facility is basically the beginnings of a Flow Boulevard. Flow Boulevards are urban boulevards that are designed to provide high capacity so the traffic “flows”. Whereas the basic Flow Boulevard concept is based upon a one-way pair of streets where there is high accessibility to fronting land use there are instances such as are included in this proposed set of improvements, which occur on Sepulveda Boulevard north of Wilshire Boulevard where Sepulveda is not paired with an adjacent street. This works in that there is mostly inaccessible adjacent land use in that area. Where there is accessible land use, careful design will be needed to keep lane capacity from dropping below acceptable levels. To gain greater understanding of Flow Boulevard characteristics the website www.FlowBoulevardPlan.com is available.
The improvements to the 405 corridor are not only to establish a facility that solves the problems that excessive traffic causes in the near term, but to provide a facility that can grow over time with further improvements and greater capacity so that future increases in travel demand can be solved for. With the completion of the widening project for the last HOV lane the 405 will be at the maximum it can safely be built; effectively it will be at its maximum capacity. The street improvements proposed in this study can provide additional present and future capacity thereby avoiding the drawbacks mentioned in the first paragraph above, for many decades. So with these first proposed improvements not only will the present day traffic problems be solved but the corridor will be secured in a form that lends itself to further improvement so that future travel demand may be solved for as well. The Flow Boulevard concept generally has three distinguishable stages. What is proposed here is essentially a Stage One facility that has a pairing of one way commercial streets with synchronized traffic signals for improved flow of traffic.
Problem Conditions to be Solved For
The 405 Fails The failing Level of Service (LOS) is basically because there is too much travel demand creating traffic that crowd onto the freeway reducing safe distances between vehicles requiring the vehicles to slow to a crawl. The optimum speed for maximum capacity with safe distances between vehicles is around 38 mph. Less than that speed, or even greater than that speed, capacity is being lost. Merging traffic is another source for slowing. The interchange of the 405 and the 10 freeways is a crucial area where slowing and LOS typically drops down then backs up with congestion away form the interchange with failing conditions. This can continue to back up until the on ramps become congested and then the streets that serve the on ramps themselves congest and back up into the surrounding community.
Neighborhood and Community “Cut through Traffic” When the commuter cannot get on an on or off ramp without a long wait or safe conditions, that driver goes looking for another opportunity. This is the source for morning and evening traffic that is working its way through the adjacent neighborhoods on residential streets moving in the direction of home or work and to an on or off ramp able to provide a receiving space. The travel demand pressure can be so great that whole communities and adjacent parallel streets are involved with excessive traffic. It is reasoned that due to the failing of the 405 the parallel boulevards and collector streets from Overland to the east and Bundy to the west of the 405 are impacted with about 80,000 vehicular trips per day that are in excess of what should be normal by community standards. This is traffic that is avoiding the congestion of the failing 405 and is searching for a path to its destination on the local streets.
Inadequate Distribution and Collection of Commuting Traffic The travel demand in the 405 corridor, which will involve the 405, Sepulveda and related major streets have more West LA destined and originating trips than there are “through” trips. This means there is a great need for distributing the traffic to the work centers and activities found in this corridor. Likewise there is a great need to collect the largely return home trips in the evening. Currently there is not enough overall north-south 405 capacity, nor is there enough opportunity given the limits of the freeway to provide the needed connections by way of turning movements onto and off of the cross street that serve the adjacent work centers and community. A facility that is more able to provide the distribution and collection is needed.
Problems Solved by the Sepulveda Flow Boulevard.
The Sepulveda Flow Boulevard (Sep/FB) Adds Capacity: Typical urban boulevards with two-way traffic, many signals for cross traffic and pedestrian street crossings as well, can have lane capacities of around 800 vehicles/lane/hour. The amount of time that pedestrians take to cross a street imposes a constraint where signals cannot be synchronized for traffic flow of the two opposing directions of traffic unless the signals are about one half mile apart or greater. With one-way traffic the pedestrian crossing the street constraint is removed and the signals can be synchronized to operate progressively to move the traffic down the street without stopping. Now the capacity is about 1300 vehicles/lane/hour, an increase of approximately 62%.
An additional corridor fact is that the northerly end of Sawtelle is at the VA property and diminishes from a 4 lane boulevard street to a two lane street at Pico when going north. Therefore there is need for a second major arterial, other than Sepulveda, to maintain continuity and capacity north-south through the West LA area. That objective can be achieved by using Cotner Avenue as the way to obtain route continuity and the additional lanes for greater capacity as well. With the coupling of Cotner and Sepulveda in a one-way street pairing manner, it forms the basis of the Sep/FB through that area south of Ohio Avenue that is effectively a bottleneck.
A recent average daily trip (ADT) count for Sepulveda was 31,000 vehicles/day. No count for Sawtelle in the area between SMB and Pico is available. Giving an 800 veh/lane/hour capacity for Sawtelle would result in about a 19,000 ADT Sawtelle facility. Combining Sepulveda and Sawtelle would be about 50,000 ADT. Comparing that to 4 lanes north and south through the West LA community with the synchronized lights of the Sep/FB, the expected ADT capacity would be about 125,000 which is a 150% increase over the existing condition.
The Sep/FB Protects the Community From Cut Through Traffic It was stated above that when the 405 goes into failure level of service that drivers avoid the congested freeway and seek other routes. It would appear this situation has broad impacts to the adjacent residential communities and their major and minor streets. On the east side of the 405 it is reasoned that westerly AM traffic on the 10 freeway will exit before the 405 interchange and seek Overland and Westwood Boulevard to get to an objective such as Westwood , UCLA, the VA and even areas west of the 405. The PM travel period is the reverse. A Sep/FB will provide the capacity to serve that traffic from the east and the drivers will not need to “cut the corner” through residential communities to get to the work center of Westwood and the education/medical center of UCLA.
West of the 405 there are a number of travel demand sources that affect the residential communities west of the 405. Beginning from the north, the Valley to City of Santa Monica (City o’SM) travel demand makes a major impact on Sunset in Brentwood. There are about 24,000 trips involved in the daily movement above what there should be and it has made an unacceptable situation. This traffic movement is addressed below in the “Improvement List” section under the item “Sunset”.
Another direction of travel demand to West LA and the City o’SM is from the east and involves all the transportation facilities from Sunset on south to below the 10 freeway. These are expected travel movements but have grown excessively due to what can be described as unbalanced and exuberant growth in the City o’SM. Growth that is unbalanced by having too much regionally oriented office space and not enough housing; and exuberant in the fact that it has deficient transportation infrastructure and relies on other communities to provide access and live with the traffic impacts as a result. There needs to be study to rectify both of those conditions.
The southerly travel demand to the West LA area and the City o’SM also involves the travel to west of the 405. The lack of sufficient corridor capacity to deliver traffic to the work centers both east and west of the 405 sends overflow traffic into residential communities both east and west, on parallel and cross streets.
The Sep/FB Provides Greater Distribution and collection of Traffic The area served on the Westside by the transportation facilities crossing the 405 from Sunset to the 10 freeway comprise some 692,000 trips daily. The 405 cannot adequately deal with the turning movements to make these connections without congestion. It will only get worse in the future as travel demand increases sending more traffic into adjacent residential communities because of backed up ramps and a failed 405. A Sep/FB facility is the “made to order” transportation facility to make up for the deficiency in turning movement connections.
Sep/FB Segments and Characteristics
Five Segments The eight mile long corridor under study has five areas with different transportation conditions to consider.
One; There is the northern segment through the Sepulveda Pass. For the most part the 405 and Sepulveda act independently each having capacity limits. It is assumed that the 405 through the pass not having major merging or effects of capacity restraints will operate at a maximum capacity determined at this time to be 350,000 vehicles per day with the completion of the final HOV segment. Without a great deal of adjacent land use access to Sepulveda Boulevard it is a bit like a limited access road. With interruptions of signals essentially at greater than half mile increments there is opportunity to obtain capacities of 1700 vehicles per hour per lane with signal synchronization and great limitation of signal time given to cross traffic within this single ROW. On a fully operating 4 lanes x 1700 veh/hour x a 13 factor would equal 88,400 vehicles per day. This means there is more capacity in the Sepulveda ROW at present even without doing intersection grade separations that can supply even greater capacities in the future.
Two; The Wilshire to Olympic segment has major distribution and collection to the streets crossing the 405 corridor (405 and Sepulveda) and their related communities and work centers.
Three; The 10 freeway intersection has a real design limitation and operates as a restraint on the capacity of the two freeways. With the final HOV lane improvement to the 405 this study for discussion purposes is determining that capacity to be approximately 280,000 vehicles per day in the 405.
Four; The National to Washington Place segment provides southern distribution and collection between the 405 and the Sep/FB as well as needed increased capacity for the corridor. This segment also has a diagonal travel demand component that produces additional north-south demand on the 405 corridor that needs to be reckoned with.
Five; South of Washington Place, and where it can be worked out, there would be closure of the Sep/FB with its one-way traffic and the return of Sepulveda and Sawtelle to two-way street traffic.
Three Alternative Sep/FB Corridors
Alternative A; This Sep/FB one-way pair of streets alternative begins south of the SMB. From the north, Sepulveda Boulevard would contain both the north and south movements of traffic until south of Santa Monica Boulevard (SMB). Between Nebraska and La Grange, at some logical and affordable point, the southerly traffic flow ROW would “take” property in order to execute a swing over in two smooth curves to align with the Cotner ROW. This southern traffic flow of the Sep/FB would continue in the Cotner ROW until just north of Pico Boulevard at which point two smooth curves would align going into the Sawtelle Boulevard ROW in the proximity of the existing intersection of Pico and Sawtelle Boulevards. From that point onward the southern flow of the Sep/FB would be in Sawtelle until the closure of the one-way pair configuration south of Culver Boulevard. The northern flowing portion of the Sep/FB would remain in the Sepulveda Boulevard ROW throughout the corridor.
Alternative B; The Sep/FB one-way pair would begin north of Ohio Avenue. At the northerly end of the “Bad News Bear Park” the southerly flowing traffic ROW would separate from the Sepulveda ROW and in two smooth curves, and tight to the 405, align with the Cotner ROW to be joined at the intersection of Cotner at Ohio. The southern flow portion of the Sep/FB one-way pair would continue on south of Olympic at which point a similar realignment to the Sawtelle Boulevard as described in Alt A takes place. The property at the corner of Pico and Cotner is presently being used by Smart and Final Market and is of adequate size to allow the “swing”.
Alternative C; This alternative is a “long shot” but is mentioned as there may be an important reason to include the VA property to the west of the 405. It is not known what that important reason is or how important it may be. However, alternatives are there to be studied so briefly it may be like the following. South of Wilshire, or even north of Wilshire a “swing” of the southerly bound Sep/FB flow would be found having an alignment west of the 405 that would eventually connect to the Beloit ROW. That ROW would be widened to adequate widths to take the southerly Sep/FB flow to approximately the vicinity of Tennessee at which point a swing to the Sawtelle ROW would occur. Southerly flow south of Pico would continue as in alternatives A and B.
The Best Choice is Alternative B
Alternative B clearly has the better layout to become the well functioning Flow Boulevard (FB) that is needed. This is important in the long run (lets say approximately 60 years if stage three were to be employed). The FB corridor is the facility that will absorb the future increase in travel demand and the one-way pair of streets separated by a single or few blocks is key for the right land use development to occur.
The 405 freeway will effectively be “maxed-out” with the completion of the last HOV lane. However, adjustments like running buses in the HOV lanes may increase person trip capacity. One day that may happen but that day is far off due to what it takes to build up transit in such a corridor. The more likely case is that the BRT transit will be generated in the Sep/FB due to the origin and destination interface.
Development of greater FB capacity is dependent on adjacent land use not only from the stand point of being a revenue source for the roadway improvements but ultimately for providing the elevated pedestrian circulation that will lift the pedestrian circulation plane out of the street level and along with it the need for vehicles to stop. Having the blocks of land use between the one-way pair provides the opportunity for the needed development. The elevated pedestrian circulation is more of a stage two improvement and necessarily a stage three improvement but needs to be planned for as it develops and before stage three is to operate. In the second stage there will be strategic grade separations of road elements to facilitate improved vehicular flow.
Alternative B, Ohio Avenue south to Pico, provides the needed blocks of land use to allow the FB to develop as it should. The potential high density commercial land use lends to being the desired revenue source for FB development but it is also the natural beneficiary of the high accessibility of the FB.
South of Pico one can expect a predominant mix of commercial and high density residential to develop. This is in complete conformance with the goals of SB 375 where high density land use transportation corridors connected to work centers are the ideal and is a main reason for the legislation.
Discussion of Sep/FB Interactions in Stage One
This is a discussion of requirements for the goals to stop the 405 from failing, to eliminate cut through traffic in adjacent residential communities and to provide for adequate distribution and collection of commuter trips within the West LA area in the near and distant future. These basic requirements may be to some extent unique to this 8 mile set of segments of the 405; there is not enough history of Flow Boulevards to know. Never the less, important relationships of these segments to each other need to be taken into account. Further it should be recognized that since human decision making and response to corridor characteristics are involved there is a basic indeterminate aspect to the functioning of traffic in the corridor. There will be a need to “balance” traffic volumes and to “instruct” drivers in their decision making to make the corridor work and the corridor to work for the drivers.
The method of discussing these corridor “relationships” and their related “issues” will be by way of the following Table A.
In General; Table A represents the operation of the 405 corridor on a typical day some time in the future when the 405 HOV lane has been added and the Sep/FB has been initially established.
In the location column, daily volumes are targeted a bit south of each of these locations by an imaginary daily vehicle cordon count line. The targeted volumes in the 405 column represent optimum/maximum volumes for that particular segment. As can be seen at either end of the locations “A” and “P”, the 405 is operating at 350,000 vehicles per day. This is expected to be more or less maximum volume in that location given that there are few interruptions such as merging or what is perceived as a major constraint to flow being the interchange of the 10 freeway with the 405. The 10 freeway constraint is depicted as having an optimum maximum daily volume of 280,000 vehicles. Between “A” and “P” the 405 volumes are diminished on the 405 to locations on either side of the 10 interchange. The task to diminish the 405 volume becomes a relationship with the Sep/FB where traffic is to be transferred from the 405 to the Sep/FB in the AM peak hours and then in the PM peak hours transferred from the Sep/FB to the 405. The Sep/FB is to take the excess traffic the 405 cannot handle without reducing LOS. It should be pointed out that excess traffic that the 405 cannot serve is currently “transferred” to adjacent residential neighborhoods as cut through traffic. By increasing capacity in the corridor by way of the Sep/FB the purpose is to not only to let the 405 operate at optimum levels of volume but is also to withdraw the cut through traffic from the residential communities by giving those drivers a more direct and swift means to seek their destination.
Balancing; Transfer volumes of vehicles are one kind of “balancing” to obtain optimum 405 performance. Another kind of “balancing” between the two facilities is in the influencing of choices to direct the origin (O) and destination (D) of the volumes of commuter trips. This can be seen in the O-D column where in the locations of M, N and O, there are some 40,000 vehicles directed by “destination” from the 405 to the Sep/FB in the AM travel period destined to the work centers of Westwood, Beverly Hills and West LA. What may be a clearer statement is that these volumes of vehicles will be “directed because of destination”. The drivers will be instructed to be better served going to the Westside work center on a flowing Sep/FB than on a 405 freeway that penalizes or even omits those turning movements in route to their destination. The design area of “balancing and instructing” will require testing and innovation treatments to effectively sort out drivers with their destinations so as to make the two transportation facilities work in concert.
The Triangle; There is another north-south “component in operation here and is expressed by the location and column name “triangle”. These are trips exchanging between the LAX, El Segundo and beach cities areas (zone letter “J” in my work) and the areas of the Mid-City and Downtown areas (zone letters “B” and “C” in my work). The triangle is delineated by the 10 freeway on the north side, the 405 on the west side, and essentially the Venice-Washington corridor on the south-eastern side. The Venice-Washington diagonal travel demand mixes as a north-south component with the 405 corridor. So trips within the triangle area are being added to and subtracted from the 405 corridor depending on their destination in the AM and reversing in the PM. On Table A this has been expressed with a clear diminishment of the 405 volume but some ambiguity as to where the trips are going between the Sep/FB and Venice-Washington Triangle component. Let it be said that both the transferring volumes and the O-D volumes will need to go through not only “balancing” but also of a kind of “training” to get the right trips on the right facilities so the combination of these facilities works smoothly. In the triangle column are represented volumes of a magnitude that would go on an improved facility, however there is not a designated facility to assign them to. The volumns appear here because it is known that the travel demand exists and that further study is needed to declare where they should be finally assigned.
South of the 10Freeway; As can be seen in the 405 and the Sep/FB columns there is a transfer of some 70,000 daily trips from the Sep/FB back to the hopefully optimized and maximized 405 capacity of 350,000 vehicles per day capacity.
Sep/FB ends at Culver; The ending of the Sep/FB would be a needed study. In this study, the West LA / 405 Corridor Improvements study has mainly been concerned with the West LA area and the traffic relationships with the 405. There has not been enough study of the Sep/FB ending to make definitive conclusions as to its ending and the relationship to the adjacent communities. In the “list” below some factors are discussed.
TABLE B (increased volumes due to growth)
Within a period of twenty five years, travel demand growth in the corridor could easily be expected to increase by twenty percent. Remember that the facility that will accommodate the increase in travel demand is the Sep/FB. The 405 is not expected to be taking additional travel demand in any significant amount after the current “widening project”. In Table A, a leeway of an additional capacity of approximately 10% for the corridor (about 40,000 vehicles per day on the Sep/FB) exists in the listed numbers. A 20% increase then would be about 80,000 more vehicles per day on the Sep/FB at each cordon line increment. This would be accommodated by going to Stage Two FB development on portions of the Sep/FB. That would entail finding those little bottlenecks and making adjustments to bring about what is essentially 1700 vehicles/lane /hour for the factored peak hours daily capacity calculation. Land use planning that helps fund that construction and begins to establish the elevated pedestrian circulation should accompany transportation development.
Another way to increase person trip capacity is to increase the BRT function on the Sep/FB. This is easily accomplished when there is the two paired one-way streets. In fact where the full width of Sepulveda south of Ohio Ave and the full width of Sawtelle south of Pico is available this could mean a fifth lane for exclusive BRT. This would actually mean that those segments of street could remain at stage One FB development for quite some time.
An important point is being made here. Due to the many different conditions in the Sep/FB; number of lanes, adjacent land use relationships and developing travel demand, there would naturally be different stages of FB development responding to those different conditions as well as the intensity of transit usage.
Sep/FB / List Of Improvements
The list is to define the needed initial construction improvements to establish the Sep/FB. The general characteristics of the number of lanes and volumes of average daily traffic (ADT) at each segment are contained in Table A and the specific alternative chosen to refer to for improvements is the Alternative B as outlined above.
Synchronization of traffic signals is a given in the development of a Stage One Flow Boulevard. And lane re-striping is also assumed to be part of FB development and will not be mentioned in the “Improvement” list. New construction, reconstruction and property acquisition are the subjects of the “improvement” in the list below.
On-street parking (both sides) for the Sepulveda ROW would occur south from Ohio Avenue to the Culver Boulevard area where the initial Sep/FB facility is intended to stop. On the south bound segments of the Sep/FB from Ohio to Pico limited on-street parking is foreseen. From Pico south to Culver boulevard on the Sawtelle ROW ample on-street parking should be accommodated for most of that length. From this initial set of improvements further improvement would evolve over time in response to travel demand, relationships to adjacent land use and community needs.
Before the list is made some definitions and scope should be made clear. The letter callouts refer to the location letters made on Table A and are indicated on the 405 Corridor Map at the end of the text. Generally the subject area will be described with “given” conditions and an “objective” stated for the area. There are only a few areas of construction to be made for the initial establishment of the Sep/FB and are set off with bullet points for convenience. There will often be references to a need for future construction for the development of greater capacity so the character and benefit of the Flow Boulevard concept is understood as a facility that continues to solve for transportation and community issues over time.
A/ Tunnel; The beginning given daily trips for this three lane tunnel on Sepulveda Boulevard is assumed to be about 30,000 vehicles per day. As time goes on and greater demand through the tunnel comes about, a reversible lane responding to AM and PM commuting from the Valley could produce 80,000 ADT through the tunnel.
N0 Improvement at this time.
B/ Skirball; The transferring of vehicles between the 405 and the Sep/FB begins (in the morning) and ends (in the evening) at this area. The existing full set of on and off ramps are adequate at this time.
No Improvement at this time.
C/ Bridge; The bridge being referred to is the bridge of the 405 over Sepulveda. Here again is a full set of on and off ramps to provide transferring of traffic between the two transportation facilities.
No Improvement at this time
D/ Church/Ovada and Moraga; There are two signaled intersections with Sepulveda at this location. The Moraga intersection includes an off ramp from the 405 as a part of that intersection. In time it would be best to consolidate the signaled intersections with Sepulveda into a one signal intersection that included an on ramp to the 405 having demo’ed the 405 off ramp (to build the on ramp). Access to the easterly residential area from the 405 would be made through the Sunset set of on and off ramps; then would be connected with Church to the area east of the 405. The entry of the new on ramp to the 405 would be situated towards the Church/Ovada intersection with Sepulveda so as to operate with that set of traffic signals. At that time signal coordination must be thought through so as to maintain traffic flow on the 4 lanes of Sepulveda. This should be accommodated easily for some period of time in that the 50,000 ADT divided by a 12.5 peak hour factor divided by four lanes equals just a 1000 vehicles per lane volume at this time. This is well below the 1300 vehicle per lane capacity generally expected in a Stage One FB condition. Much further off in time, maybe 20 years, in order to obtain a Stage Two volume through this area a grade separated intersection with Church/Ovada would be needed to attain the 1700 vehicles per hour per lane.
No Improvement at this time
E/ Sunset; Basically there is not an objective to have connections between the Sep/FB and Sunset Boulevard. At present there is a one way ramp like street connection from Sunset down to Sepulveda where Sepulveda goes through under Sunset. The left turn onto Sepulveda is a turning movement that would want to be eliminated as traffic volumes increase. The right turn (to go north) may be continued if interference with Sep/FB traffic flow does not occur. It should be said that since there is no connection intended between the Sep/FB and Sunset that there is no future improvement to this location anticipated as well.
No Improvement at this time
Solution to congestion in Brentwood
It should be noted here that in this study it has been evident that the commuter volumes from the Valley exchanging with the City of Santa Monica (City o’SM) produce the excessive congestion on Sunset Boulevard between the 405 and Brentwood (and beyond). This finding is an excess of 26,000 commuter trips making the “cut off” through Brentwood to the C o’SM and back in the evening. Therefore this study recommends that the southern bound AM 405 off ramp to Sunset should be closed for the morning commuting and that the Sunset on ramp north to the 405 should be closed to the PM commuter traffic. The reasoning here is that if there is no longer a failing 405 where traffic backs up from the 10 freeway interchange there will be reasonably rapid and “as intended” connection between the Valley and the City o’SM that can be made by the freeways of the 405 and 10 without cutting through residential communities. Note that Brentwood is basically a bedroom community and that commutes to the Valley will use the open on-ramp north onto the 405 in the AM and the open off-ramp south to Sunset in the PM.
F/ Constitution; Constitution is a “T” intersection with Sepulveda at the tunnel/underpass from the west side of the 405. Some Brentwood traffic and others may find the opportunity for access to the south and the particular connections the Sep/FB affords more attractive than the south bound 405 on ramp at Sunset. Church Street south of Sunset would be the feeder to the connecting tunnel of Constitution to south bound Sep/FB. There has been discussion of a Subway station west of the 405 on the VA property. There may be need for park and ride or a BRT connection in which case a right turn off south bound Sep/FB through the tunnel would be a welcome connection. The limitation of a right turn off and a right turn onto the Sep/FB is recommended; no left turns that stop opposing traffic on the Sep/FB in other words
• No Improvement at this time other than a connection with Church Street
G/ Wilshire; The current widening improvements to the 405 will also have a complete set of ramps and make very good connections to Wilshire Boulevard. This means trips connecting the 405 and Wilshire happen through that interchange. A more limited set of turning movements are encouraged for the Sep/FB. Specifically to limit left hand turns on and off of the Sep/FB during the proposed Stage One Sep/FB development where no widening to Sepulveda is expected to take place as a part of the “405 Widening” project. These turning movement opportunities and limitations make the commuter select their approach between the 405 or the Sep/FB as they come through the pass from the Valley or from the south below the 10 freeway interchange. This is part of the need for “balancing” to make the overall corridor work.
No Improvement at this time
H/ Ohio; North of Ohio is where it is proposed to separate the south bound Sep/FB lanes from the north bound Sep/FB lanes in the Sepulveda ROW. On the north-west corner of Sepulveda and Ohio is a small park that if some of its recreation facilities were reorganized could continue to operate as a park and accommodate the south bound lanes of the Sep/FB that need to be aligned with Cotner at the intersection of Ohio and Cotner. The three main facilities in the park at present are a baseball diamond, parking lot and tennis courts. If the tennis courts were in effect moved over to the Westside Recreation Center east of Sepulveda and grouped with those tennis courts, the baseball diamond and the associated parking could be arranged to accommodate the two smooth curves of south bound lanes tight to the 405 to align with Cotner.
The Ohio Avenue traffic movements need to have study. Presently they present residential “cut through” traffic on either side of the 405. Ohio provides the exchange of traffic between Westwood and areas west of the 405. A more efficient SMB, and Wilshire for that matter, without traffic congestion trying to get on or off the 405 could take on that travel demand. This would allow a simple right-in and right-out of the residential area to the east of Sepulveda on Ohio. No cross Sepulveda traffic on Ohio would be permitted. A similar condition for the residential area as it relates to connecting with the south bound Sep/FB lanes would be advised. The present segment of Ohio Avenue between would become a one-way street connection from Sepulveda to Cotner to facilitate a north to south direction change on the Sep/FB.
• Improvement to align south bound Sep/FB traffic to Cotner is Required. Associated reorganization is required as well.
I/ Santa Monica Boulevard (SMB); The list now considers east and west intersections with the Sep/FB. It is important to recognize that the intersection of the Sep/FB and SMB is potentially a “corner” on a proposed LA Basin Flow Boulevard Loop. The loop around the Basin would provide needed circulation and for the distribution and collection function that is so important in the 405 corridor. More on the LA Basin loop proposal can be found at www.FlowBoulevardPlan.com.
SMB east; The wide ROW (100 ft generally) allows opportunities for special lane treatments as well as an exclusive BRT lane. What would be important for this intersection from a corridor stand point is to develop adequate distribution and collection for commuters to use the Sep/FB. This would replace the need for major 405 involvement in this function. This relates to the idea that various cross street intersections will receive specialized treatment and be part of the way commuter traffic is “balanced” between the two facilities; the 405 and the Sep/FB. Essentially at this intersection it is foreseen that 3 turning lanes (one optional) turning right from north bound Sep/FB into SMB to go east and from west bound SMB turning right to go north on Sep/FB should be provided.
No Improvement at this time
SMB west; The Cotner ROW has been imposed upon both north and south of SMB by ramping for the 405. With the corridor “balancing” concept in mind as well as the fact that there is presently congestion into SMB by traffic trying to get on and off the 405; less traffic exchanging between the 405 and SMB should be made. This means that the 405 ramping that has taken ROW from Cotner shall be given back to the original Cotner ROW. The 405 ramps shall be moved closer to the 405 and possibly room should be made for bus pockets connected to Sep/FB operation as well.
Balancing options that simplify signals directing turning movement as well as limiting turning movements should be studied to make the multiple intersection work. An example of this is for the south bound 405 off ramp not to allow a left turn onto SMB during morning commute. This clears the intersection of that turning movement and lets the 3 lanes (one optional) of south bound Sep/FB/Cotner traffic turn east onto SMB to satisfy the demand. Another concept is to coordinate turning movements from both the 405 and Sep/FB to act at the same time as if it were one facility in order to simplify the turning movements of the intersections.
• Improvement to the Cotner ROW with additional width to be made. This means reducing 405 ramp lanes and moving those lanes closer to the freeway.
Olympic east; The intersection of Olympic Boulevard and the 405 corridor is an important one. Olympic is not a Freeway or a Flow Boulevard, but it is a major highway connecting residential communities east-west and becomes a connection from the 405 corridor to work centers beyond the corridor. There is only a north bound on-ramp to the 405 and a south bound off ramp, neither of which has direct connection with Olympic. This makes the connection of the Sep/FB all the more important for it can alleviate congestion by giving greater distribution and collection in the corridor further relieving the 405 of traffic. Multiple turning lanes on and off the Sep/FB, both east and west can be made available.
No Improvement at this time
Olympic west; Similar to the intersection with Sepulveda the Cotner intersection can have multiple turning lanes on and off going east or west on Olympic.
No Improvement at this time
Pico east; This intersection can be similar to the Olympic east intersection on Sepulveda.
No Improvement at this time
Pico west; This is where there is major improvement to provide alignment of Cotner with Sawtelle for the south bound portion of the Sep/FB. The north-west corner parcel of Cotner and Pico will need to be acquired and should be large enough to provide the smooth curve transitions desirable for aligning with the Sawtelle ROW. Study of alternative designs regarding whether to align at the Sawtelle-Pico intersection, somewhat south of that intersection (in effect enlarging it to the south) or definitely south of the intersection with a revised set of turning movements for the existing Sawtelle-Pico intersection should be made.
Along with traffic movement considerations there are considerable structural issues involving the existing overcrossing of the 405 above Pico and on down to the Exposition ROW. There are rows of columns adjacent to Pico on approximately 25 foot centers. And then there are freeway spans going south similar to the 75 foot (plus) Pico Boulevard span continuing south. Aligning the Cotner to Sawtelle ROW will need to incorporate the structural issues involved here. In that there is an approximate clear height of 28 feet from the ground to the underside of the freeway there is plenty of depth available to construct new supporting beams of the 405 to provide the larger spans to accommodate the new Cotner to Sawtelle transition ROW weaving its way below the 405.
• Improvement must be made to provide realignment of the south bound Sep/FB.
Take note; south of Pico is the proposed Expo Phase II light rail project in the Exposition ROW. The current plans provide a grade separation for the Sawtelle roadway. The Sepulveda ROW crossing is currently designed at grade, however there are alternative plans to provide a grade separated crossing if someone can find the money to make the aerial structure and station happen.
L/ 405 / 10 Freeway Interchange; The interchange is a significant part of the corridor from the stand point it is a part of the corridor that is not to be allowed to slip below LOS “C”. Improvements to this area to maintain LOS C or better is on Caltran to reason how. It would be helpful however if there was more of a connection with a Sep/FB facility to relieve the freeway interchange of the turning movements that are now provided by the “directional ramps” between freeways.
National east and west; Multiple left and right turns on and off of the Sep/FB can be made available for accommodating traffic.
No Improvement at this time
N/ The triangle Area; The triangle area is not an intersection but a number of intersections from National on south to Culver Boulevard that are effected by a diagonal (north-east to south-west) travel demand that can effect the north-south 405 corridor that includes the Sep/FB. It is not a pressing issue at this time but at some time in the future it will probably made traffic pressures on the 405 corridor affecting balancing and capacity characteristics.
No improvement at this time
O/ Venice and Washington; Venice and Washington are taken together here in that it is observed that this will be the solution to the impending diagonal travel demand in the area described as the “triangle”. The solution referred to is the making of a Flow Boulevard out of Venice and Washington so as to consolidation the diagonal pattern of travel demand into commercial streets that connect to the Mid-City and Downtown areas beyond. The 10 freeway that begins to parallel the potential Venice-Washington FB can solve the same kind of traffic problems that are now being discussed in the 405 corridor.
Regarding intersections of both Venice and Washington with both Sepulveda and Sawtelle figure that single or multiple turning movements can be developed according to further study at the specific intersection.
No Improvements at this time
P/ Culver Boulevard; This is the vicinity where it is proposed that the Sep/FB is to be ended and that the one-way streets of Sepulveda and Sawtelle return to operating with two way traffic. A part of the Sep/FB operation with the 405 is to provide help in sorting out the distribution and collection volumes of traffic from one facility to the other. Presently there is an on-ramp from Culver Boulevard to the north bound 405 lanes. It is more important to distribute traffic to the Sep/FB from the 405 so the ram area should be changed from an onramp to an off-ramp. There is presently an on-ramp to the 405 south of Braddock. There may be a need to make a clearer or better connection from the Sep/FB/Sawtelle facility to the 405 on-ramp.
• Ramp improvements between the 405 and the Sep/FB.
IN CONCLUSION THE STUDY RECOMMENDS
In conclusion it is worthwhile to touch upon the larger context of transportation and community planning in Los Angeles. Obviously they should occur together so as to add up well for the City and County. The 405 corridor should be a clear example of the need and kind of problem solving it can provide.
Los Angeles needs better transportation, a better economy and to become a better City. Flow Boulevards can be instrumental in making all of that happen.
Flow Boulevards provide a growth solution to a sprawled and vulnerable city form by making strong urban transportation corridors that also include higher density land use that connect to work centers. And they become an indispensable part of a new economy. A new economy that replaces the economy of sprawl that no longer really works in Los Angeles. Shorter trip length and Bus Rapid Transit is a part of the consolidation outcome making less travel per capita in LA County. While this new urban fabric creates new desirable residential and commercial places, it also protects existing communities as well.
Read the new FB 2010 section of www.FlowBoulevardPlan.com where subjects of a: New Economy, Vision, Objectives and Disconnects are discussed, to make a better City.