Highways Agency - Safe roads, Reliable journeys, Informed travellers

5. Assessment of the M1 HOV Scheme

5.1 Assessment Options

To determine the options for the assessment of the impacts of the M1 HOV scheme, the following factors have been considered:

• What are the objectives of the scheme?
• How important is each objective, in terms of benefits to stakeholders (e.g. users and the Highways Agency)?
• How can the objectives be achieved?
• What is the expected impact of the scheme in achieving each objective?
• How can the extent to which each objective has been met be measured?
• How expensive would it be to carry out the assessment?
• How easy would it be to detect any changes that have occurred following the introduction of the scheme

In addition, the assessment of the M1 HOV scheme must consider operational issues for the scheme:

• Whether drivers are complying, or if rogue vehicles are using the HOV lane.
• Whether drivers are using the scheme properly. This will include an assessment of the proportion of eligible drivers who are choosing to use the HOV lane, and whether drivers understand the signs.

These operational issues will provide an indication of whether the scheme is functioning efficiently, and whether there could be a benefit from modifying the operation of the scheme, e.g. the times of opening, the level of enforcement or the road layout.

When assessing the impacts of the HOV scheme, the Monitoring Consultant must allow for the effect of any changes unrelated to the scheme:

• The underlying traffic conditions will have changed during the construction period for the widening scheme. In particular, the widened M1 is likely to attract additional traffic (either from the adjoining network, or new traffic). This information will be provided by the Scheme Consultant.
• There may have been physical changes (apart from the widening) during the construction period. For example, the carriageway lighting or the road surface may have significantly changed or new service areas may have been built. The effect of any changes to the adjoining network must also be taken into account.
• The assessment should take account of external influences on traffic, e.g. special events, weather conditions and incidents on the surrounding network.
• The section of the M1 between Junctions 10 and 13 may be widened during the "after" period for the HOV scheme. Any effects of the widening must be taken into account. On the northbound carriageway, queues might tail back onto the pilot site or one lane might be coned off on the approach to Junction 10. On the southbound carriageway, flows onto the pilot site might be constrained by the presence of the roadworks.
• There may be changes in traffic behaviour that are not a direct effect of the scheme. Any national and/or local trends should be obtained by identifying and monitoring suitable control sites.

The remaining effects will be attributable to the HOV scheme. The effect of the scheme may vary on different days, at different times of the day, or for different vehicle types. The effects will also vary in different lanes. The scheme may also have an effect outside the times when it is operational (e.g. drivers might be uncertain whether they can use the lane). The assessment of the scheme should include an analysis of all of these effects.

The widened M1 is likely to have a Variable Speed Limit system installed, which will display reduced speed limits during periods of high flow (see Section 2). It is still to be decided whether a reduced speed limit should be displayed for safety reasons whenever the HOV lane is open. If such a reduced speed limit is imposed, then the effects of this speed limit should be assessed as part of the impact of the HOV scheme. However, if the reduced speed limits are introduced as a result of the widening (i.e. they are due to the normal operation of the Variable Speed Limit system), then the effects of the reduced speed limits should be disaggregated from the effects of the HOV scheme.

Table 1 provides more detail on the objectives of the HOV scheme, and provides information on assessing the extent to which each of these objectives is achieved. For each objective, the following information is provided:

• The importance of the objective, in terms of benefits to stakeholders (e.g. users and the Highways Agency). It is classed as High, Medium or Low, relative to the importance of the other objectives. A high importance means that improvements will show a large benefit; a low importance means that improvements may be of little value.
• How the objective can be achieved. For the objectives that may have a direct impact, this is a description of how the impact will be achieved. For the operational issues, this is a description of how the information can be obtained.
• The expected impact of the HOV scheme in achieving the objective. It is classed as High, Medium or Low, relative to the impacts for the other objectives. A high impact means that a large improvement is expected following the introduction of the HOV lane; a low impact means that any improvement is likely to be small.
  
  Some of the objectives are expressed as avoiding a disbenefit (e.g. "avoid new accident risks"). If the impact is classed as High, it means that it is expected that the HOV scheme will be successful in avoiding the disbenefit. Therefore, a rating of High implies that the scheme will be successful in achieving the objective.

The Importance and Impact information has been assessed subjectively.

Table 1 lists all of the objectives that could be assessed, including Accessibility and Integration objectives specified by WebTAG (shown in italicised typeface). These options for assessment have been reviewed by an independent panel of experts.

Table 1 - Objectives of HOV scheme

5.2 Assessment Strategy

Following discussions with the HA in consultation with an independent panel of experts, it has been decided that all of the options for assessment listed in Table 1 should be included in the assessment strategy, with the exception of the Accessibility and Integration objectives, since these are not directly relevant to the HOV scheme. The effect of the scheme on these objectives will be neutral.

Table 2 provides more information on the assessment of the HOV scheme. It expands on the information in Table 1, providing the following additional information:

• How the extent to which the objectives have been met can be measured. This is a list of the types of data that can be collected before and after the scheme is installed. Any differences in the results will show the impact of the scheme on that objective.
• The cost of carrying out the assessment (i.e. data collection and analysis). The cost is classed as High, Medium or Low, relative to the costs to assess the other objectives. The cost is an average for the data types.
• How easy it would be to measure changes to the data types. The measurability is classed as High, Medium or Low, relative to the measurability of the data required to assess the other objectives. A high measurability means that changes to the data can be easily detected; a low measurability means that changes to the data may not be detected.

The Cost and Measurability information has been assessed subjectively. They are for a "before" and "after" study combined. In some cases, it will be cheaper and easier to measure performance indicators in the "after" period, when additional data sources (e.g. MIDAS data) will be available.

Some of the performance indicators are quantitative (e.g. flows and speeds) and some are qualitative (e.g. driver surveys and opinions of emergency services). In general, the quantitative measures are less costly to collect than the qualitative measures, and any changes are easier to detect.

There is a trade-off between the amount of data that is collected and the cost of collecting the data. For example, when determining the amount of data to be collected from the adjoining road network, a large amount of data is potentially desirable. The impacts of the HOV scheme will become less apparent as the distance from the M1 pilot site increases. At some point, it is not cost effective to collect the data.

In addition, the effect of the scheme on safety on the surrounding network will be difficult to measure. Accident rates at the junction roundabouts could be monitored. Apart from this, there would be too many unknown variables for any safety study on the wider surrounding network to identify a significant change in safety (or even to provide an indication of side effects on safety from direct measurement). It is recommended that flow levels on the wider surrounding network should be used as a proxy for safety. If there is a change in traffic levels using the surrounding network following the introduction of the HOV scheme, then this would be likely to have an impact on safety. The Local Authority may be able to provide some flow and accident data for the surrounding network. In addition, flow levels joining and leaving the motorway will provide some information on flows on the surrounding network.

Table 2 lists all of the objectives that could be assessed. The objectives to be assessed by the Monitoring Consultant are shown in Table 2 in black typeface. A few objectives are outside the remit of the Monitoring Consultant and are likely to be the responsibility of the Scheme Consultant rather than the Monitoring Consultant (see Section 4); these are shown in Table 2 in red italicised typeface.

The results of the assessment by the Monitoring Consultant will provide the information to be used by the Scheme Consultant to achieve the objectives for which they have responsibility.

Table 2 - Assessment of HOV scheme

The impacts of introducing an HOV lane will be assessed by the Monitoring Consultant by comparing the "before" and "after" data collected. The comparison in the "after" period will be against the expected effects of simply widening the M1 (i.e. not implementing an HOV lane). The anticipated effects of widening the M1 will be determined by modelling; it is envisaged that this modelling will be carried out by the Scheme Consultant as part of the widening work.

Overall flow levels and travel patterns in the M1 corridor may change during the construction period (this is anticipated to last for 3 years), and these must be taken into account during the monitoring. Changes in flow levels and travel patterns will be determined by the Monitoring Consultant, probably via Origin/Destination surveys.

Underlying changes in traffic behaviour between the "before" and "after" periods should also be taken into account. Changes might have occurred in vehicle occupancy, lane discipline, accident rates and overall traffic speeds. In addition, there will be a general traffic growth from year to year. To obtain information on the underlying changes, it is recommended that several Control Sites should be monitored. The Monitoring Consultant should identify suitable Control Sites. The Control Sites should have similar characteristics to the M1, should be in the South-east (as driver behaviour varies across the country), and should be far enough away from the M1 not to be affected by the widening or the roadworks.

5.3 People affected by the scheme

For every traffic scheme, there are people who would gain and people who would lose (or perceive themselves to lose) from the introduction of the scheme.

The people who perceive disbenefits are likely to be the people who object to and complain about the scheme. The assessment strategy should consider how the results of the assessment could be presented to address the concerns of these people. For the M1 HOV scheme, it is recommended that:

• Estimates should be made of the disbenefit to specific groups and of the overall benefit, in advance of the scheme becoming operational. Advance publicity should mitigate the effect of the scheme on the people who perceive disbenefits.
• Any disbenefits to specific groups should be calculated once the scheme is operational. These results could then be used to counter complaints from this group. It is likely that they would perceive themselves as suffering greater disbenefits than is actually the case. In fact, they may not be suffering disbenefits at all, just not benefiting by as much as other users.

The gainers and losers could be specific stakeholder groups or subsets of these groups. (Stakeholders are people who may be affected by a new scheme.) The stakeholder groups for the M1 HOV scheme are:

• Private car users
• Business users
• HGV users
• Bus and coach users
• Motorcycle users
• Residents (surrounding areas)
• Local businesses (including hotels)
• Authorities
  • Ministers
  • DfT
  • HA
  • Local Authorities
  • Regional Planning body
  • Scheme Consultant
• Police
• Emergency Services
• Automobile Association and RAC
• Regional Control Centres
• Freight hauliers
• Bus and coach operators
• Rail operators
• Luton Airport authority
• Environmental agencies and interests
• Road maintenance contractors

For the M1 HOV scheme, the main groups of people who will gain are drivers and occupants of HOVs. They will have reduced delays and their journey time reliability will also improve.

The main losers will be drivers of single occupancy vehicles. They may have increased delays and their journey time reliability may also deteriorate. In addition, the Police may feel that enforcement of the HOV lane is not an effective use of their time. People who may perceive a disbenefit could include drivers who are confused by the additional signing or who object to control measures in general.

It is recommended that opinions should be sought from relevant stakeholder groups, both before and after the scheme is installed.

2. Influencing travel behaviour will be achieved via the means listed under the other subject areas in Table 1. back [2]

3. The influence of the HOV scheme on travel behaviour will be assessed via the other methods listed in Table 2. back [3]